Jeremiah P. Depta, MD, MPHS

In view of current evidence, we do not recommend routinely using aspirin for primary prevention of cardiovascular disease, even in patients with diabetes mellitus. The decision must be individualized on the basis of the patient’s risks of cardiovascular disease and bleeding, especially the risk of serious bleeding events such as gastrointestinal and intracranial hemorrhage.

For example, patients with a family history of myocardial infarction at an early age and patients who smoke or have multiple cardiovascular risk factors may be most likely to benefit, whereas those with risk factors for gastrointestinal bleeding such as dyspepsia or ulcer would not be good candidates. Of note, current recommendations are mixed and confusing and will need to be reevaluated as new trial data become available.

TRIALS THAT SET THE STAGE FOR CURRENT PRACTICE

Routine use of aspirin for primary prevention of cardiovascular disease remains controversial.^1,2 Aspirin’s safety and efficacy for this indication was studied in six major trials (Table 1).^3–8 In the late 1980s, the first two primary prevention trials of aspirin enrolled healthy male physicians who had minimal cardiovascular risk factors^3,4:

The British Doctors’ Trial³ observed no significant differences between aspirin (300–500 mg/day) and no aspirin in the rates of the primary end point of cardiovascular death or in the individual secondary end points of nonfatal myocardial infarction, nonfatal stroke, or bleeding.³

The Physicians’ Health Study⁴ found no differences in the rates of cardiovascular mortality or ischemic stroke between aspirin (325 mg every other day) and placebo. The rate of nonfatal myocardial infarction was significantly lower with aspirin than with placebo, but with a higher risk of bleeding. Relative risks and 95% confidence intervals with aspirin vs placebo:

• Nonfatal myocardial infarction
  0.59 (0.47–0.74), P < .00001
• Bleeding
  1.32 (1.25–1.40), P < .00001
• Blood transfusions
  1.71 (1.09–2.69), P = .02
• Hemorrhagic stroke
  2.14 (0.96–4.77), P = .06.

A subgroup analysis revealed that the benefit of aspirin for myocardial infarction in the Physicians’ Health Study was predominantly in those age 50 and older.4 This finding established the common clinical practice of routinely using aspirin for primary prevention in men age 50 and older.¹

Later, aspirin for primary prevention was studied in four trials,^5–8 three of which enrolled patients at higher cardiovascular risk^5–7:

The Thrombosis Prevention Trial⁵ was conducted in men in the highest quintile of cardiovascular risk. The aspirin dosage was 75 mg/day.

The Hypertension Optimal Treatment⁶ trial included men and women ages 50 to 80 with hypertension. Aspirin dosage: 75 mg/day.

The Primary Prevention Project⁷ involved men and women age 50 and older with at least one risk factor for cardiovascular disease.^1,5–7 The aspirin dosage was 100 mg/day.

 In these trials (Table 1), aspirin significantly lowered the rate of ischemic events compared with placebo or control: nonfatal myocardial infarction in the Thrombosis Prevention Trial; myocardial infarction and major adverse cardiac event (ie, cardiovascular death, myocardial infarction, or stroke) in the Hypertension Optimal Treatment trial; and cardiovascular mortality and major cardiovascular events (cardiovascular death, nonfatal myocardial infarction, nonfatal stroke, angina pectoris, transient ischemic attack, peripheral artery disease, or revascularization procedures) in the Primary Prevention Project. However, aspirin’s benefit in each trial was largely offset by a higher rate of various bleeding end points.^5–7

The Women’s Health Study

A subgroup analysis of the Hypertension Optimal Treatment trial suggested that sex may influence the efficacy of aspirin—specifically, aspirin did not prevent nonfatal myocardial infarction in women.⁹ Given the paucity of female participants in the previous primary prevention trials, the Women’s Health Study⁸ was designed to determine the efficacy and safety of aspirin (100 mg every other day) in women age 45 and older with very few cardiovascular risk factors.⁸

Aspirin did not significantly reduce the rate of the primary end point of cardiovascular death, myocardial infarction, or stroke, though a significant effect was observed in the subgroup of women age 65 and older. Although overall the Women’s Health Study found no benefit in the rate of myocardial infarction, there was a significant reduction in the rate of ischemic stroke (which needs to be interpreted cautiously in an overall neutral trial) and a nonsignificant increase in the rate of hemorrhagic stroke. As in other trials, rates of bleeding, including gastrointestinal bleeding, were higher with aspirin.

A meta-analysis of six trials of aspirin for primary prevention

In 2009, the Antithrombotic Trialists’ Collaboration¹⁰ published a meta-analysis of six trials of aspirin for primary prevention. In this analysis, aspirin did not reduce the rate of cardiovascular death, but it did reduce the yearly risk of:

• Death from coronary heart disease or nonfatal myocardial infarction
  (0.28% vs 0.34%, P < .0001)
• Nonfatal myocardial infarction
  (0.18% vs 0.23%, P < .0001)
• Ischemic stroke
  (0.11% vs 0.12%, P = .05).¹⁰

Despite aspirin’s apparent efficacy, the absolute yearly risk for major extracranial bleeding and hemorrhagic stroke was also significantly increased with aspirin use by 0.3% and 0.1%, respectively. The efficacy of aspirin for preventing all serious vascular events (vascular death, myocardial infarction, or stroke) was similar in men and women.¹⁰ The authors concluded that the net benefit of aspirin did not outweigh the increased risks of bleeding.

WHAT ABOUT PATIENTS WITH DIABETES?

When considering whether to prescribe aspirin for primary prevention, the individual patient’s risks of cardiovascular disease and bleeding must be carefully assessed. Those at highest risk of cardiovascular disease and at low risk of bleeding may still benefit, but current evidence does not clearly support this strategy.

For example, diabetes mellitus has traditionally been considered a coronary heart disease equivalent, and aspirin was routinely prescribed as “secondary prevention.”¹¹ In the six trials of aspirin for primary prevention, the prevalence of diabetic patients ranged from 1% to 17%, the efficacy of aspirin in this subgroup was inconsistent among the trials, and aspirin did not confer a net clinical benefit according to the 2009 Antithrombotic Trialists’ Collaboration meta-analysis.^1,3–8,10

Additionally, two trials of aspirin for primary prevention in diabetes^12,13 failed to demonstrate significant efficacy for aspirin compared with no aspirin, either in Japanese patients with type 2 diabetes and no history of cardiovascular disease¹² or in patients with asymptomatic peripheral artery disease.¹³

Thus, the current evidence for aspirin for primary prevention in diabetes does not demonstrate a net clinical benefit, but ongoing trials (Table 2) may provide evidence for the use of aspirin in this important subgroup.

An important finding from the 2009 Antithrombotic Trialists’ Collaboration was that traditional risk factors for cardiovascular disease also increase the risk of major bleeding, thus making it difficult to determine who will receive the maximum net clinical benefit.¹⁰ Additionally, many of the aspirin primary prevention trials predated the widespread use of statins and the current lower prevalence of smoking, which may further limit the generalizability of the positive signals seen in earlier trials.

THE DATA ARE MIXED, BUT ONE MESSAGE IS CLEAR

Based on the current available evidence, the US Food and Drug Administration recently issued a Consumer Update that does not support aspirin for primary prevention and warns patients about the risk of serious bleeding complications.¹⁴ Moreover, current guidelines and consensus panels (Table 3) for aspirin in primary prevention differ from one another,^15–21 making it challenging for clinicians to determine which patients would benefit. One message is clear in the most current clinical guidelines, namely, that routine use of aspirin for primary prevention is not recommended.^15–21 Several ongoing trials may resolve this important clinical dilemma.

In view of current evidence, we do not recommend routinely using aspirin for primary prevention of cardiovascular disease, even in patients with diabetes mellitus. The decision must be individualized on the basis of the patient’s risks of cardiovascular disease and bleeding, especially the risk of serious bleeding events such as gastrointestinal and intracranial hemorrhage.

For example, patients with a family history of myocardial infarction at an early age and patients who smoke or have multiple cardiovascular risk factors may be most likely to benefit, whereas those with risk factors for gastrointestinal bleeding such as dyspepsia or ulcer would not be good candidates. Of note, current recommendations are mixed and confusing and will need to be reevaluated as new trial data become available.

TRIALS THAT SET THE STAGE FOR CURRENT PRACTICE

Routine use of aspirin for primary prevention of cardiovascular disease remains controversial.^1,2 Aspirin’s safety and efficacy for this indication was studied in six major trials (Table 1).^3–8 In the late 1980s, the first two primary prevention trials of aspirin enrolled healthy male physicians who had minimal cardiovascular risk factors^3,4:

The British Doctors’ Trial³ observed no significant differences between aspirin (300–500 mg/day) and no aspirin in the rates of the primary end point of cardiovascular death or in the individual secondary end points of nonfatal myocardial infarction, nonfatal stroke, or bleeding.³

The Physicians’ Health Study⁴ found no differences in the rates of cardiovascular mortality or ischemic stroke between aspirin (325 mg every other day) and placebo. The rate of nonfatal myocardial infarction was significantly lower with aspirin than with placebo, but with a higher risk of bleeding. Relative risks and 95% confidence intervals with aspirin vs placebo:

• Nonfatal myocardial infarction
  0.59 (0.47–0.74), P < .00001
• Bleeding
  1.32 (1.25–1.40), P < .00001
• Blood transfusions
  1.71 (1.09–2.69), P = .02
• Hemorrhagic stroke
  2.14 (0.96–4.77), P = .06.

A subgroup analysis revealed that the benefit of aspirin for myocardial infarction in the Physicians’ Health Study was predominantly in those age 50 and older.4 This finding established the common clinical practice of routinely using aspirin for primary prevention in men age 50 and older.¹

Later, aspirin for primary prevention was studied in four trials,^5–8 three of which enrolled patients at higher cardiovascular risk^5–7:

The Thrombosis Prevention Trial⁵ was conducted in men in the highest quintile of cardiovascular risk. The aspirin dosage was 75 mg/day.

The Hypertension Optimal Treatment⁶ trial included men and women ages 50 to 80 with hypertension. Aspirin dosage: 75 mg/day.

The Primary Prevention Project⁷ involved men and women age 50 and older with at least one risk factor for cardiovascular disease.^1,5–7 The aspirin dosage was 100 mg/day.

 In these trials (Table 1), aspirin significantly lowered the rate of ischemic events compared with placebo or control: nonfatal myocardial infarction in the Thrombosis Prevention Trial; myocardial infarction and major adverse cardiac event (ie, cardiovascular death, myocardial infarction, or stroke) in the Hypertension Optimal Treatment trial; and cardiovascular mortality and major cardiovascular events (cardiovascular death, nonfatal myocardial infarction, nonfatal stroke, angina pectoris, transient ischemic attack, peripheral artery disease, or revascularization procedures) in the Primary Prevention Project. However, aspirin’s benefit in each trial was largely offset by a higher rate of various bleeding end points.^5–7

The Women’s Health Study

A subgroup analysis of the Hypertension Optimal Treatment trial suggested that sex may influence the efficacy of aspirin—specifically, aspirin did not prevent nonfatal myocardial infarction in women.⁹ Given the paucity of female participants in the previous primary prevention trials, the Women’s Health Study⁸ was designed to determine the efficacy and safety of aspirin (100 mg every other day) in women age 45 and older with very few cardiovascular risk factors.⁸

Aspirin did not significantly reduce the rate of the primary end point of cardiovascular death, myocardial infarction, or stroke, though a significant effect was observed in the subgroup of women age 65 and older. Although overall the Women’s Health Study found no benefit in the rate of myocardial infarction, there was a significant reduction in the rate of ischemic stroke (which needs to be interpreted cautiously in an overall neutral trial) and a nonsignificant increase in the rate of hemorrhagic stroke. As in other trials, rates of bleeding, including gastrointestinal bleeding, were higher with aspirin.

A meta-analysis of six trials of aspirin for primary prevention

In 2009, the Antithrombotic Trialists’ Collaboration¹⁰ published a meta-analysis of six trials of aspirin for primary prevention. In this analysis, aspirin did not reduce the rate of cardiovascular death, but it did reduce the yearly risk of:

• Death from coronary heart disease or nonfatal myocardial infarction
  (0.28% vs 0.34%, P < .0001)
• Nonfatal myocardial infarction
  (0.18% vs 0.23%, P < .0001)
• Ischemic stroke
  (0.11% vs 0.12%, P = .05).¹⁰

Despite aspirin’s apparent efficacy, the absolute yearly risk for major extracranial bleeding and hemorrhagic stroke was also significantly increased with aspirin use by 0.3% and 0.1%, respectively. The efficacy of aspirin for preventing all serious vascular events (vascular death, myocardial infarction, or stroke) was similar in men and women.¹⁰ The authors concluded that the net benefit of aspirin did not outweigh the increased risks of bleeding.

WHAT ABOUT PATIENTS WITH DIABETES?

When considering whether to prescribe aspirin for primary prevention, the individual patient’s risks of cardiovascular disease and bleeding must be carefully assessed. Those at highest risk of cardiovascular disease and at low risk of bleeding may still benefit, but current evidence does not clearly support this strategy.

For example, diabetes mellitus has traditionally been considered a coronary heart disease equivalent, and aspirin was routinely prescribed as “secondary prevention.”¹¹ In the six trials of aspirin for primary prevention, the prevalence of diabetic patients ranged from 1% to 17%, the efficacy of aspirin in this subgroup was inconsistent among the trials, and aspirin did not confer a net clinical benefit according to the 2009 Antithrombotic Trialists’ Collaboration meta-analysis.^1,3–8,10

Additionally, two trials of aspirin for primary prevention in diabetes^12,13 failed to demonstrate significant efficacy for aspirin compared with no aspirin, either in Japanese patients with type 2 diabetes and no history of cardiovascular disease¹² or in patients with asymptomatic peripheral artery disease.¹³

Thus, the current evidence for aspirin for primary prevention in diabetes does not demonstrate a net clinical benefit, but ongoing trials (Table 2) may provide evidence for the use of aspirin in this important subgroup.

An important finding from the 2009 Antithrombotic Trialists’ Collaboration was that traditional risk factors for cardiovascular disease also increase the risk of major bleeding, thus making it difficult to determine who will receive the maximum net clinical benefit.¹⁰ Additionally, many of the aspirin primary prevention trials predated the widespread use of statins and the current lower prevalence of smoking, which may further limit the generalizability of the positive signals seen in earlier trials.

THE DATA ARE MIXED, BUT ONE MESSAGE IS CLEAR

Based on the current available evidence, the US Food and Drug Administration recently issued a Consumer Update that does not support aspirin for primary prevention and warns patients about the risk of serious bleeding complications.¹⁴ Moreover, current guidelines and consensus panels (Table 3) for aspirin in primary prevention differ from one another,^15–21 making it challenging for clinicians to determine which patients would benefit. One message is clear in the most current clinical guidelines, namely, that routine use of aspirin for primary prevention is not recommended.^15–21 Several ongoing trials may resolve this important clinical dilemma.

In view of current evidence, we do not recommend routinely using aspirin for primary prevention of cardiovascular disease, even in patients with diabetes mellitus. The decision must be individualized on the basis of the patient’s risks of cardiovascular disease and bleeding, especially the risk of serious bleeding events such as gastrointestinal and intracranial hemorrhage.

For example, patients with a family history of myocardial infarction at an early age and patients who smoke or have multiple cardiovascular risk factors may be most likely to benefit, whereas those with risk factors for gastrointestinal bleeding such as dyspepsia or ulcer would not be good candidates. Of note, current recommendations are mixed and confusing and will need to be reevaluated as new trial data become available.

TRIALS THAT SET THE STAGE FOR CURRENT PRACTICE

Routine use of aspirin for primary prevention of cardiovascular disease remains controversial.^1,2 Aspirin’s safety and efficacy for this indication was studied in six major trials (Table 1).^3–8 In the late 1980s, the first two primary prevention trials of aspirin enrolled healthy male physicians who had minimal cardiovascular risk factors^3,4:

The British Doctors’ Trial³ observed no significant differences between aspirin (300–500 mg/day) and no aspirin in the rates of the primary end point of cardiovascular death or in the individual secondary end points of nonfatal myocardial infarction, nonfatal stroke, or bleeding.³

The Physicians’ Health Study⁴ found no differences in the rates of cardiovascular mortality or ischemic stroke between aspirin (325 mg every other day) and placebo. The rate of nonfatal myocardial infarction was significantly lower with aspirin than with placebo, but with a higher risk of bleeding. Relative risks and 95% confidence intervals with aspirin vs placebo:

• Nonfatal myocardial infarction
  0.59 (0.47–0.74), P < .00001
• Bleeding
  1.32 (1.25–1.40), P < .00001
• Blood transfusions
  1.71 (1.09–2.69), P = .02
• Hemorrhagic stroke
  2.14 (0.96–4.77), P = .06.

A subgroup analysis revealed that the benefit of aspirin for myocardial infarction in the Physicians’ Health Study was predominantly in those age 50 and older.4 This finding established the common clinical practice of routinely using aspirin for primary prevention in men age 50 and older.¹

Later, aspirin for primary prevention was studied in four trials,^5–8 three of which enrolled patients at higher cardiovascular risk^5–7:

The Thrombosis Prevention Trial⁵ was conducted in men in the highest quintile of cardiovascular risk. The aspirin dosage was 75 mg/day.

The Hypertension Optimal Treatment⁶ trial included men and women ages 50 to 80 with hypertension. Aspirin dosage: 75 mg/day.

The Primary Prevention Project⁷ involved men and women age 50 and older with at least one risk factor for cardiovascular disease.^1,5–7 The aspirin dosage was 100 mg/day.

 In these trials (Table 1), aspirin significantly lowered the rate of ischemic events compared with placebo or control: nonfatal myocardial infarction in the Thrombosis Prevention Trial; myocardial infarction and major adverse cardiac event (ie, cardiovascular death, myocardial infarction, or stroke) in the Hypertension Optimal Treatment trial; and cardiovascular mortality and major cardiovascular events (cardiovascular death, nonfatal myocardial infarction, nonfatal stroke, angina pectoris, transient ischemic attack, peripheral artery disease, or revascularization procedures) in the Primary Prevention Project. However, aspirin’s benefit in each trial was largely offset by a higher rate of various bleeding end points.^5–7

The Women’s Health Study

A subgroup analysis of the Hypertension Optimal Treatment trial suggested that sex may influence the efficacy of aspirin—specifically, aspirin did not prevent nonfatal myocardial infarction in women.⁹ Given the paucity of female participants in the previous primary prevention trials, the Women’s Health Study⁸ was designed to determine the efficacy and safety of aspirin (100 mg every other day) in women age 45 and older with very few cardiovascular risk factors.⁸

Aspirin did not significantly reduce the rate of the primary end point of cardiovascular death, myocardial infarction, or stroke, though a significant effect was observed in the subgroup of women age 65 and older. Although overall the Women’s Health Study found no benefit in the rate of myocardial infarction, there was a significant reduction in the rate of ischemic stroke (which needs to be interpreted cautiously in an overall neutral trial) and a nonsignificant increase in the rate of hemorrhagic stroke. As in other trials, rates of bleeding, including gastrointestinal bleeding, were higher with aspirin.

A meta-analysis of six trials of aspirin for primary prevention

In 2009, the Antithrombotic Trialists’ Collaboration¹⁰ published a meta-analysis of six trials of aspirin for primary prevention. In this analysis, aspirin did not reduce the rate of cardiovascular death, but it did reduce the yearly risk of:

• Death from coronary heart disease or nonfatal myocardial infarction
  (0.28% vs 0.34%, P < .0001)
• Nonfatal myocardial infarction
  (0.18% vs 0.23%, P < .0001)
• Ischemic stroke
  (0.11% vs 0.12%, P = .05).¹⁰

Despite aspirin’s apparent efficacy, the absolute yearly risk for major extracranial bleeding and hemorrhagic stroke was also significantly increased with aspirin use by 0.3% and 0.1%, respectively. The efficacy of aspirin for preventing all serious vascular events (vascular death, myocardial infarction, or stroke) was similar in men and women.¹⁰ The authors concluded that the net benefit of aspirin did not outweigh the increased risks of bleeding.

WHAT ABOUT PATIENTS WITH DIABETES?

When considering whether to prescribe aspirin for primary prevention, the individual patient’s risks of cardiovascular disease and bleeding must be carefully assessed. Those at highest risk of cardiovascular disease and at low risk of bleeding may still benefit, but current evidence does not clearly support this strategy.

For example, diabetes mellitus has traditionally been considered a coronary heart disease equivalent, and aspirin was routinely prescribed as “secondary prevention.”¹¹ In the six trials of aspirin for primary prevention, the prevalence of diabetic patients ranged from 1% to 17%, the efficacy of aspirin in this subgroup was inconsistent among the trials, and aspirin did not confer a net clinical benefit according to the 2009 Antithrombotic Trialists’ Collaboration meta-analysis.^1,3–8,10

Additionally, two trials of aspirin for primary prevention in diabetes^12,13 failed to demonstrate significant efficacy for aspirin compared with no aspirin, either in Japanese patients with type 2 diabetes and no history of cardiovascular disease¹² or in patients with asymptomatic peripheral artery disease.¹³

Thus, the current evidence for aspirin for primary prevention in diabetes does not demonstrate a net clinical benefit, but ongoing trials (Table 2) may provide evidence for the use of aspirin in this important subgroup.

An important finding from the 2009 Antithrombotic Trialists’ Collaboration was that traditional risk factors for cardiovascular disease also increase the risk of major bleeding, thus making it difficult to determine who will receive the maximum net clinical benefit.¹⁰ Additionally, many of the aspirin primary prevention trials predated the widespread use of statins and the current lower prevalence of smoking, which may further limit the generalizability of the positive signals seen in earlier trials.

THE DATA ARE MIXED, BUT ONE MESSAGE IS CLEAR

Based on the current available evidence, the US Food and Drug Administration recently issued a Consumer Update that does not support aspirin for primary prevention and warns patients about the risk of serious bleeding complications.¹⁴ Moreover, current guidelines and consensus panels (Table 3) for aspirin in primary prevention differ from one another,^15–21 making it challenging for clinicians to determine which patients would benefit. One message is clear in the most current clinical guidelines, namely, that routine use of aspirin for primary prevention is not recommended.^15–21 Several ongoing trials may resolve this important clinical dilemma.

An 85-year-old woman presented to the emergency department with a 2-hour history of dyspnea, dizziness, generalized weakness, nausea, and diaphoresis. Her medical history included hypertension, end-stage renal disease with hemodialysis, and atrial fibrillation.

She had an arteriovenous fistula for dialysis access in her right upper arm, with erythema around the site.

Her creatine kinase level was 1,434 U/L (normal range 30–220), creatine kinase MB 143.4 ng/mL (0.0–8.8 ng/mL), and troponin T 0.1 ng/mL (0.0–0.1 ng/mL). She had ST elevation in leads I and aVL. She was taken for emergency cardiac catheterization.

Three blood cultures were drawn on the day of cardiac catheterization. Two grew gram-positive organisms: one grew coagulase-negative Staphylococcus, and the other grew gram-positive bacilli (anaerobic, non-sporeforming). On the basis of these findings, intravenous vancomycin (Vancocin) was started. Seventy-two hours later, one of two blood cultures again grew coagulase-negative Staphylococcus. Five days after the start of antibiotic treatment, blood cultures were negative, and the patient received intravenous vancomycin for 4 weeks (from the time the blood cultures became negative) for native mitral valve endocarditis.

EMBOLISM AND ENDOCARDITIS: KEY FEATURES

An embolic event occurs in 22% to 50% of cases of infective endocarditis and can involve the lungs, bowel, other organs, or extremities.¹ The incidence of embolization of the coronary arteries in patients with infective endocarditis is unknown, but in one case series² it occurred in 8 (7.5%) of 107 cases. The most common site of coronary embolism is the LAD.³

Myocardial infarction is a rare complication of coronary artery embolization.² It was reported in 17 (2.9%) of 586 consecutive patients with infective endocarditis.⁴ In patients with infectious endocarditis complicated by myocardial infarction, the death rate was nearly double that seen in patients with infective endocarditis without myocardial infarction (64% vs 33%).⁴

TREATMENT

The best treatment for this complication of infective endocarditis is not known, as it has not been well studied. The high death rate in these patients makes restoration of coronary perfusion essential.

Thrombolytics are usually avoided in patients with septic embolization because of concerns about concurrent intracerebral mycotic aneurysms and the risk of hemorrhage.

Percutaneous transluminal angioplasty carries a risk of distal mobilization of emboli, development of mycotic aneurysm at the balloon dilation site, or reocclusion due to a mobile embolus.⁵ Stent placement may improve vessel patency but carries a theoretic risk of infection in bacteremic patients. Percutaneous embolectomy has also been used either prior to or instead of stent placement.⁶ Surgical options include embolectomy in patients who may require surgery, and coronary artery bypass grafting for patients with chronic embolization.⁷

An 85-year-old woman presented to the emergency department with a 2-hour history of dyspnea, dizziness, generalized weakness, nausea, and diaphoresis. Her medical history included hypertension, end-stage renal disease with hemodialysis, and atrial fibrillation.

She had an arteriovenous fistula for dialysis access in her right upper arm, with erythema around the site.

Her creatine kinase level was 1,434 U/L (normal range 30–220), creatine kinase MB 143.4 ng/mL (0.0–8.8 ng/mL), and troponin T 0.1 ng/mL (0.0–0.1 ng/mL). She had ST elevation in leads I and aVL. She was taken for emergency cardiac catheterization.

Three blood cultures were drawn on the day of cardiac catheterization. Two grew gram-positive organisms: one grew coagulase-negative Staphylococcus, and the other grew gram-positive bacilli (anaerobic, non-sporeforming). On the basis of these findings, intravenous vancomycin (Vancocin) was started. Seventy-two hours later, one of two blood cultures again grew coagulase-negative Staphylococcus. Five days after the start of antibiotic treatment, blood cultures were negative, and the patient received intravenous vancomycin for 4 weeks (from the time the blood cultures became negative) for native mitral valve endocarditis.

EMBOLISM AND ENDOCARDITIS: KEY FEATURES

An embolic event occurs in 22% to 50% of cases of infective endocarditis and can involve the lungs, bowel, other organs, or extremities.¹ The incidence of embolization of the coronary arteries in patients with infective endocarditis is unknown, but in one case series² it occurred in 8 (7.5%) of 107 cases. The most common site of coronary embolism is the LAD.³

Myocardial infarction is a rare complication of coronary artery embolization.² It was reported in 17 (2.9%) of 586 consecutive patients with infective endocarditis.⁴ In patients with infectious endocarditis complicated by myocardial infarction, the death rate was nearly double that seen in patients with infective endocarditis without myocardial infarction (64% vs 33%).⁴

TREATMENT

The best treatment for this complication of infective endocarditis is not known, as it has not been well studied. The high death rate in these patients makes restoration of coronary perfusion essential.

Thrombolytics are usually avoided in patients with septic embolization because of concerns about concurrent intracerebral mycotic aneurysms and the risk of hemorrhage.

Percutaneous transluminal angioplasty carries a risk of distal mobilization of emboli, development of mycotic aneurysm at the balloon dilation site, or reocclusion due to a mobile embolus.⁵ Stent placement may improve vessel patency but carries a theoretic risk of infection in bacteremic patients. Percutaneous embolectomy has also been used either prior to or instead of stent placement.⁶ Surgical options include embolectomy in patients who may require surgery, and coronary artery bypass grafting for patients with chronic embolization.⁷

An 85-year-old woman presented to the emergency department with a 2-hour history of dyspnea, dizziness, generalized weakness, nausea, and diaphoresis. Her medical history included hypertension, end-stage renal disease with hemodialysis, and atrial fibrillation.

She had an arteriovenous fistula for dialysis access in her right upper arm, with erythema around the site.

Her creatine kinase level was 1,434 U/L (normal range 30–220), creatine kinase MB 143.4 ng/mL (0.0–8.8 ng/mL), and troponin T 0.1 ng/mL (0.0–0.1 ng/mL). She had ST elevation in leads I and aVL. She was taken for emergency cardiac catheterization.

Three blood cultures were drawn on the day of cardiac catheterization. Two grew gram-positive organisms: one grew coagulase-negative Staphylococcus, and the other grew gram-positive bacilli (anaerobic, non-sporeforming). On the basis of these findings, intravenous vancomycin (Vancocin) was started. Seventy-two hours later, one of two blood cultures again grew coagulase-negative Staphylococcus. Five days after the start of antibiotic treatment, blood cultures were negative, and the patient received intravenous vancomycin for 4 weeks (from the time the blood cultures became negative) for native mitral valve endocarditis.

EMBOLISM AND ENDOCARDITIS: KEY FEATURES

An embolic event occurs in 22% to 50% of cases of infective endocarditis and can involve the lungs, bowel, other organs, or extremities.¹ The incidence of embolization of the coronary arteries in patients with infective endocarditis is unknown, but in one case series² it occurred in 8 (7.5%) of 107 cases. The most common site of coronary embolism is the LAD.³

Myocardial infarction is a rare complication of coronary artery embolization.² It was reported in 17 (2.9%) of 586 consecutive patients with infective endocarditis.⁴ In patients with infectious endocarditis complicated by myocardial infarction, the death rate was nearly double that seen in patients with infective endocarditis without myocardial infarction (64% vs 33%).⁴

TREATMENT

The best treatment for this complication of infective endocarditis is not known, as it has not been well studied. The high death rate in these patients makes restoration of coronary perfusion essential.

Thrombolytics are usually avoided in patients with septic embolization because of concerns about concurrent intracerebral mycotic aneurysms and the risk of hemorrhage.

Percutaneous transluminal angioplasty carries a risk of distal mobilization of emboli, development of mycotic aneurysm at the balloon dilation site, or reocclusion due to a mobile embolus.⁵ Stent placement may improve vessel patency but carries a theoretic risk of infection in bacteremic patients. Percutaneous embolectomy has also been used either prior to or instead of stent placement.⁶ Surgical options include embolectomy in patients who may require surgery, and coronary artery bypass grafting for patients with chronic embolization.⁷

Many clinicians are concerned about a possible interaction between the proton pump inhibitor omeprazole (Prilosec) and the antiplatelet drug clopidogrel (Plavix), which is often given to patients as part of dual antiplatelet therapy after an acute coronary syndrome or a percutaneous coronary intervention. Indeed, the US Food and Drug Administration (FDA) has warned that omeprazole reduces the antiplatelet effect of clopidogrel.

Although we should not take such warnings lightly, we also should not be alarmed. The data on which the FDA warning was based came mostly from laboratory assays of platelet function. Preliminary results from a randomized, controlled clinical trial with hard end points show that, for the time being, we should not change the way we manage patients.

PROTON PUMP INHIBITORS DECREASE GASTROINTESTINAL BLEEDING

Dual antiplatelet therapy with aspirin and clopidogrel decreases the risk of major adverse cardiac events after an acute coronary syndrome or a percutaneous coronary intervention compared with aspirin alone.¹ However, it also increases the risk of gastrointestinal bleeding. A recent analysis determined that dual antiplatelet therapy was the most significant risk factor associated with serious or fatal gastrointestinal bleeding in high-risk survivors of myocardial infarction.²

Given the risks of significant morbidity and death in patients on dual antiplatelet therapy who develop gastrointestinal bleeding, an expert consensus panel recommended the use of proton pump inhibitors in patients on dual antiplatelet therapy who have risk factors for gastrointestinal bleeding.³ Accordingly, these drugs are commonly used for gastrointestinal protection in patients requiring dual antiplatelet therapy.

A POSSIBLE CYP450 INTERACTION

Clopidogrel is metabolized from a prodrug to its active metabolite by the cytochrome P450 (CYP450) system. Proton pump inhibitors also are metabolized by the CYP450 system.⁴ Proton pump inhibitors are thought to diminish the activity of clopidogrel via inhibition of the CYP2C19 isoenzyme. However, the clinical significance of this inhibition is not clear. Different drugs of this class inhibit the CYP450 system to varying degrees.

The potential interaction between proton pump inhibitors and clopidogrel is worrisome for many physicians, since adverse cardiovascular outcomes are more common in patients in whom the antiplatelet response to clopidogrel is impaired.¹ This interaction led to the publication of numerous articles, and prompted the FDA to carefully analyze the potential clinical implications.

In several randomized trials, omeprazole diminished the response to clopidogrel (measured via platelet function assays).^5,6 It is unclear if this is a class effect, as proton pump inhibitors other than omeprazole have not consistently been shown to have this effect.^6,7 Observational studies of the effect of co-administration of a proton pump inhibitor and clopidogrel on cardiovascular outcomes following acute coronary syndromes have had conflicting findings.^8–11

THE FDA ISSUES AN ADVISORY

Given the reports of an impaired platelet response to clopidogrel with omeprazole, the FDA asked the manufacturer for data on this potential interaction. The data showed diminished platelet inhibition when clopidogrel was co-administered with omeprazole or when the two were taken 12 hours apart.

On November 17, 2009, the FDA issued a patient advisory and updated the patient safety information on the package insert for clopidogrel about this drug interaction.¹² Specifically, the FDA warns that omeprazole reduces the antiplatelet effect of clopidogrel by about 50%. The FDA warning sparked debate in the medical community, as the decision was based in part on ex vivo data.

POST HOC ANALYSES FROM RANDOMIZED CONTROLLED TRIALS

Several post hoc analyses of large randomized clinical trials have studied the potential interaction between proton pump inhibitors and clopidogrel.

In the Clopidogrel for the Reduction of Events During Observation (CREDO) trial, clopidogrel reduced the incidence of death, myocardial infarction, or stroke to a similar extent regardless of baseline use of a proton pump inhibitor.¹³

In patients undergoing percutaneous coronary intervention, the Prasugrel in Comparison to Clopidogrel for Inhibition of Platelet Activation and Aggregation—Thrombolysis in Myocardial Infarction 44 (PRINCIPLE-TIMI 44) trial found that those taking a proton pump inhibitor had significantly less platelet inhibition with clopidogrel compared with those not on one.¹⁴ However, patients taking prasugrel (Effient) and a proton pump inhibitor only had a slight trend towards diminished platelet inhibition.¹⁴

The Trial to Assess Improvement in Therapeutic Outcomes by Optimizing Platelet Inhibition With Prasugrel—Thrombolysis in Myocardial Infarction 38 (TRITON-TIMI 38) found that proton pump inhibitors did not influence the long-term outcome of cardiovascular death, myocardial infarction, or stroke for patients on clopidogrel or prasugrel after an acute coronary syndrome.¹⁴ A subanalysis did not reveal any differences between omeprazole or other drugs of this class as to an effect on the primary outcome.

Though informative, the results of these post hoc analyses need to be validated with data from randomized clinical trials.

‘COGENT’ TRIAL HALTED EARLY, BUT PRELIMINARY RESULTS AVAILABLE

The Clopidogrel and the Optimization of Gastrointestinal Events (COGENT) trial was the first randomized clinical study of the effect of the interaction between clopidogrel and omeprazole on cardiovascular and gastrointestinal outcomes.¹⁵ In a double-blind fashion, patients with acute coronary syndromes or undergoing percutaneous coronary interventions were randomized to receive a fixed-dose combination pill containing either clopidogrel and delayed-release omeprazole or clopidogrel alone. All patients also received aspirin.

Unfortunately, the trial was stopped early because the sponsor declared bankruptcy. However, preliminary results revealed no significant difference in cardiovascular outcomes for patients on clopidogrel and omeprazole compared with clopidogrel alone.¹⁵ Furthermore, adverse gastrointestinal events were significantly fewer in patients on clopidogrel and omeprazole.

Thus, omeprazole appears to be safe and may offer gastrointestinal protection to patients on dual antiplatelet therapy, though we need to await publication of the full results.

‘SPICE ’ TRIAL TO EVALUATE POSSIBLE MECHANISMS OF INTERACTION

The Evaluation of the Influence of Statins and Proton Pump Inhibitors on Clopidogrel Antiplatelet Effects (SPICE) trial is a mechanistic study that will evaluate platelet function and genetic polymorphisms in patients on clopidogrel and aspirin after a percutaneous coronary intervention. They will be randomized to statin therapy plus different proton pump inhibitors.¹⁶ Prior concerns about an ex vivo interaction between clopidogrel and certain statins were not validated by clinical data.¹⁷

OUR RECOMMENDATIONS

Based on the current evidence, patients on aspirin and clopidogrel who have an indication for a proton pump inhibitor or who are at risk of gastrointestinal bleeding can continue or start taking a proton pump inhibitor, including omeprazole.

Switching to another proton pump inhibitor is not currently supported by any randomized clinical trial, nor is changing to a histamine H₂-receptor antagonist. The effect of proton pump inhibitors other than omeprazole on clopidogrel is unclear, and it is not known if the interaction with clopidogrel is a class effect or specific to certain drugs of this class.¹⁸ On the other hand, we still have no compelling evidence of any major clinical interaction between alternative proton pump inhibitors and clopidogrel.¹⁸

Also, separating the dosing times of clopidogrel and omeprazole by 12 hours is not supported by any randomized clinical trial, and runs contrary to at least some ex vivo data.

It is important that all physicians assess the need for a proton pump inhibitor in their patients, as overuse of these drugs has been documented in certain settings.¹⁹

Clopidogrel and omeprazole share a common metabolic link via CYP2C19. Omeprazole, along with some other proton pump inhibitors, interacts with clopidogrel at the level of the CYP450 system. Platelet function studies show that platelet inhibition by clopidogrel is impaired, though the astute clinician should be aware of the wide variability associated with platelet function assays and clopidogrel.^1,20 However, what may appear to be an interaction at the enzymatic level does not necessarily translate into worse clinical outcomes. Additionally, reliance on nonrandomized studies rather than on randomized clinical trials can be misleading.

Many clinicians are concerned about a possible interaction between the proton pump inhibitor omeprazole (Prilosec) and the antiplatelet drug clopidogrel (Plavix), which is often given to patients as part of dual antiplatelet therapy after an acute coronary syndrome or a percutaneous coronary intervention. Indeed, the US Food and Drug Administration (FDA) has warned that omeprazole reduces the antiplatelet effect of clopidogrel.

Although we should not take such warnings lightly, we also should not be alarmed. The data on which the FDA warning was based came mostly from laboratory assays of platelet function. Preliminary results from a randomized, controlled clinical trial with hard end points show that, for the time being, we should not change the way we manage patients.

PROTON PUMP INHIBITORS DECREASE GASTROINTESTINAL BLEEDING

Dual antiplatelet therapy with aspirin and clopidogrel decreases the risk of major adverse cardiac events after an acute coronary syndrome or a percutaneous coronary intervention compared with aspirin alone.¹ However, it also increases the risk of gastrointestinal bleeding. A recent analysis determined that dual antiplatelet therapy was the most significant risk factor associated with serious or fatal gastrointestinal bleeding in high-risk survivors of myocardial infarction.²

Given the risks of significant morbidity and death in patients on dual antiplatelet therapy who develop gastrointestinal bleeding, an expert consensus panel recommended the use of proton pump inhibitors in patients on dual antiplatelet therapy who have risk factors for gastrointestinal bleeding.³ Accordingly, these drugs are commonly used for gastrointestinal protection in patients requiring dual antiplatelet therapy.

A POSSIBLE CYP450 INTERACTION

Clopidogrel is metabolized from a prodrug to its active metabolite by the cytochrome P450 (CYP450) system. Proton pump inhibitors also are metabolized by the CYP450 system.⁴ Proton pump inhibitors are thought to diminish the activity of clopidogrel via inhibition of the CYP2C19 isoenzyme. However, the clinical significance of this inhibition is not clear. Different drugs of this class inhibit the CYP450 system to varying degrees.

The potential interaction between proton pump inhibitors and clopidogrel is worrisome for many physicians, since adverse cardiovascular outcomes are more common in patients in whom the antiplatelet response to clopidogrel is impaired.¹ This interaction led to the publication of numerous articles, and prompted the FDA to carefully analyze the potential clinical implications.

In several randomized trials, omeprazole diminished the response to clopidogrel (measured via platelet function assays).^5,6 It is unclear if this is a class effect, as proton pump inhibitors other than omeprazole have not consistently been shown to have this effect.^6,7 Observational studies of the effect of co-administration of a proton pump inhibitor and clopidogrel on cardiovascular outcomes following acute coronary syndromes have had conflicting findings.^8–11

THE FDA ISSUES AN ADVISORY

Given the reports of an impaired platelet response to clopidogrel with omeprazole, the FDA asked the manufacturer for data on this potential interaction. The data showed diminished platelet inhibition when clopidogrel was co-administered with omeprazole or when the two were taken 12 hours apart.

On November 17, 2009, the FDA issued a patient advisory and updated the patient safety information on the package insert for clopidogrel about this drug interaction.¹² Specifically, the FDA warns that omeprazole reduces the antiplatelet effect of clopidogrel by about 50%. The FDA warning sparked debate in the medical community, as the decision was based in part on ex vivo data.

POST HOC ANALYSES FROM RANDOMIZED CONTROLLED TRIALS

Several post hoc analyses of large randomized clinical trials have studied the potential interaction between proton pump inhibitors and clopidogrel.

In the Clopidogrel for the Reduction of Events During Observation (CREDO) trial, clopidogrel reduced the incidence of death, myocardial infarction, or stroke to a similar extent regardless of baseline use of a proton pump inhibitor.¹³

In patients undergoing percutaneous coronary intervention, the Prasugrel in Comparison to Clopidogrel for Inhibition of Platelet Activation and Aggregation—Thrombolysis in Myocardial Infarction 44 (PRINCIPLE-TIMI 44) trial found that those taking a proton pump inhibitor had significantly less platelet inhibition with clopidogrel compared with those not on one.¹⁴ However, patients taking prasugrel (Effient) and a proton pump inhibitor only had a slight trend towards diminished platelet inhibition.¹⁴

The Trial to Assess Improvement in Therapeutic Outcomes by Optimizing Platelet Inhibition With Prasugrel—Thrombolysis in Myocardial Infarction 38 (TRITON-TIMI 38) found that proton pump inhibitors did not influence the long-term outcome of cardiovascular death, myocardial infarction, or stroke for patients on clopidogrel or prasugrel after an acute coronary syndrome.¹⁴ A subanalysis did not reveal any differences between omeprazole or other drugs of this class as to an effect on the primary outcome.

Though informative, the results of these post hoc analyses need to be validated with data from randomized clinical trials.

‘COGENT’ TRIAL HALTED EARLY, BUT PRELIMINARY RESULTS AVAILABLE

The Clopidogrel and the Optimization of Gastrointestinal Events (COGENT) trial was the first randomized clinical study of the effect of the interaction between clopidogrel and omeprazole on cardiovascular and gastrointestinal outcomes.¹⁵ In a double-blind fashion, patients with acute coronary syndromes or undergoing percutaneous coronary interventions were randomized to receive a fixed-dose combination pill containing either clopidogrel and delayed-release omeprazole or clopidogrel alone. All patients also received aspirin.

Unfortunately, the trial was stopped early because the sponsor declared bankruptcy. However, preliminary results revealed no significant difference in cardiovascular outcomes for patients on clopidogrel and omeprazole compared with clopidogrel alone.¹⁵ Furthermore, adverse gastrointestinal events were significantly fewer in patients on clopidogrel and omeprazole.

Thus, omeprazole appears to be safe and may offer gastrointestinal protection to patients on dual antiplatelet therapy, though we need to await publication of the full results.

‘SPICE ’ TRIAL TO EVALUATE POSSIBLE MECHANISMS OF INTERACTION

The Evaluation of the Influence of Statins and Proton Pump Inhibitors on Clopidogrel Antiplatelet Effects (SPICE) trial is a mechanistic study that will evaluate platelet function and genetic polymorphisms in patients on clopidogrel and aspirin after a percutaneous coronary intervention. They will be randomized to statin therapy plus different proton pump inhibitors.¹⁶ Prior concerns about an ex vivo interaction between clopidogrel and certain statins were not validated by clinical data.¹⁷

OUR RECOMMENDATIONS

Based on the current evidence, patients on aspirin and clopidogrel who have an indication for a proton pump inhibitor or who are at risk of gastrointestinal bleeding can continue or start taking a proton pump inhibitor, including omeprazole.

Switching to another proton pump inhibitor is not currently supported by any randomized clinical trial, nor is changing to a histamine H₂-receptor antagonist. The effect of proton pump inhibitors other than omeprazole on clopidogrel is unclear, and it is not known if the interaction with clopidogrel is a class effect or specific to certain drugs of this class.¹⁸ On the other hand, we still have no compelling evidence of any major clinical interaction between alternative proton pump inhibitors and clopidogrel.¹⁸

Also, separating the dosing times of clopidogrel and omeprazole by 12 hours is not supported by any randomized clinical trial, and runs contrary to at least some ex vivo data.

It is important that all physicians assess the need for a proton pump inhibitor in their patients, as overuse of these drugs has been documented in certain settings.¹⁹

Clopidogrel and omeprazole share a common metabolic link via CYP2C19. Omeprazole, along with some other proton pump inhibitors, interacts with clopidogrel at the level of the CYP450 system. Platelet function studies show that platelet inhibition by clopidogrel is impaired, though the astute clinician should be aware of the wide variability associated with platelet function assays and clopidogrel.^1,20 However, what may appear to be an interaction at the enzymatic level does not necessarily translate into worse clinical outcomes. Additionally, reliance on nonrandomized studies rather than on randomized clinical trials can be misleading.

Many clinicians are concerned about a possible interaction between the proton pump inhibitor omeprazole (Prilosec) and the antiplatelet drug clopidogrel (Plavix), which is often given to patients as part of dual antiplatelet therapy after an acute coronary syndrome or a percutaneous coronary intervention. Indeed, the US Food and Drug Administration (FDA) has warned that omeprazole reduces the antiplatelet effect of clopidogrel.

Although we should not take such warnings lightly, we also should not be alarmed. The data on which the FDA warning was based came mostly from laboratory assays of platelet function. Preliminary results from a randomized, controlled clinical trial with hard end points show that, for the time being, we should not change the way we manage patients.

PROTON PUMP INHIBITORS DECREASE GASTROINTESTINAL BLEEDING

Dual antiplatelet therapy with aspirin and clopidogrel decreases the risk of major adverse cardiac events after an acute coronary syndrome or a percutaneous coronary intervention compared with aspirin alone.¹ However, it also increases the risk of gastrointestinal bleeding. A recent analysis determined that dual antiplatelet therapy was the most significant risk factor associated with serious or fatal gastrointestinal bleeding in high-risk survivors of myocardial infarction.²

Given the risks of significant morbidity and death in patients on dual antiplatelet therapy who develop gastrointestinal bleeding, an expert consensus panel recommended the use of proton pump inhibitors in patients on dual antiplatelet therapy who have risk factors for gastrointestinal bleeding.³ Accordingly, these drugs are commonly used for gastrointestinal protection in patients requiring dual antiplatelet therapy.

A POSSIBLE CYP450 INTERACTION

Clopidogrel is metabolized from a prodrug to its active metabolite by the cytochrome P450 (CYP450) system. Proton pump inhibitors also are metabolized by the CYP450 system.⁴ Proton pump inhibitors are thought to diminish the activity of clopidogrel via inhibition of the CYP2C19 isoenzyme. However, the clinical significance of this inhibition is not clear. Different drugs of this class inhibit the CYP450 system to varying degrees.

The potential interaction between proton pump inhibitors and clopidogrel is worrisome for many physicians, since adverse cardiovascular outcomes are more common in patients in whom the antiplatelet response to clopidogrel is impaired.¹ This interaction led to the publication of numerous articles, and prompted the FDA to carefully analyze the potential clinical implications.

In several randomized trials, omeprazole diminished the response to clopidogrel (measured via platelet function assays).^5,6 It is unclear if this is a class effect, as proton pump inhibitors other than omeprazole have not consistently been shown to have this effect.^6,7 Observational studies of the effect of co-administration of a proton pump inhibitor and clopidogrel on cardiovascular outcomes following acute coronary syndromes have had conflicting findings.^8–11

THE FDA ISSUES AN ADVISORY

Given the reports of an impaired platelet response to clopidogrel with omeprazole, the FDA asked the manufacturer for data on this potential interaction. The data showed diminished platelet inhibition when clopidogrel was co-administered with omeprazole or when the two were taken 12 hours apart.

On November 17, 2009, the FDA issued a patient advisory and updated the patient safety information on the package insert for clopidogrel about this drug interaction.¹² Specifically, the FDA warns that omeprazole reduces the antiplatelet effect of clopidogrel by about 50%. The FDA warning sparked debate in the medical community, as the decision was based in part on ex vivo data.

POST HOC ANALYSES FROM RANDOMIZED CONTROLLED TRIALS

Several post hoc analyses of large randomized clinical trials have studied the potential interaction between proton pump inhibitors and clopidogrel.

In the Clopidogrel for the Reduction of Events During Observation (CREDO) trial, clopidogrel reduced the incidence of death, myocardial infarction, or stroke to a similar extent regardless of baseline use of a proton pump inhibitor.¹³

In patients undergoing percutaneous coronary intervention, the Prasugrel in Comparison to Clopidogrel for Inhibition of Platelet Activation and Aggregation—Thrombolysis in Myocardial Infarction 44 (PRINCIPLE-TIMI 44) trial found that those taking a proton pump inhibitor had significantly less platelet inhibition with clopidogrel compared with those not on one.¹⁴ However, patients taking prasugrel (Effient) and a proton pump inhibitor only had a slight trend towards diminished platelet inhibition.¹⁴

The Trial to Assess Improvement in Therapeutic Outcomes by Optimizing Platelet Inhibition With Prasugrel—Thrombolysis in Myocardial Infarction 38 (TRITON-TIMI 38) found that proton pump inhibitors did not influence the long-term outcome of cardiovascular death, myocardial infarction, or stroke for patients on clopidogrel or prasugrel after an acute coronary syndrome.¹⁴ A subanalysis did not reveal any differences between omeprazole or other drugs of this class as to an effect on the primary outcome.

Though informative, the results of these post hoc analyses need to be validated with data from randomized clinical trials.

‘COGENT’ TRIAL HALTED EARLY, BUT PRELIMINARY RESULTS AVAILABLE

The Clopidogrel and the Optimization of Gastrointestinal Events (COGENT) trial was the first randomized clinical study of the effect of the interaction between clopidogrel and omeprazole on cardiovascular and gastrointestinal outcomes.¹⁵ In a double-blind fashion, patients with acute coronary syndromes or undergoing percutaneous coronary interventions were randomized to receive a fixed-dose combination pill containing either clopidogrel and delayed-release omeprazole or clopidogrel alone. All patients also received aspirin.

Unfortunately, the trial was stopped early because the sponsor declared bankruptcy. However, preliminary results revealed no significant difference in cardiovascular outcomes for patients on clopidogrel and omeprazole compared with clopidogrel alone.¹⁵ Furthermore, adverse gastrointestinal events were significantly fewer in patients on clopidogrel and omeprazole.

Thus, omeprazole appears to be safe and may offer gastrointestinal protection to patients on dual antiplatelet therapy, though we need to await publication of the full results.

‘SPICE ’ TRIAL TO EVALUATE POSSIBLE MECHANISMS OF INTERACTION

The Evaluation of the Influence of Statins and Proton Pump Inhibitors on Clopidogrel Antiplatelet Effects (SPICE) trial is a mechanistic study that will evaluate platelet function and genetic polymorphisms in patients on clopidogrel and aspirin after a percutaneous coronary intervention. They will be randomized to statin therapy plus different proton pump inhibitors.¹⁶ Prior concerns about an ex vivo interaction between clopidogrel and certain statins were not validated by clinical data.¹⁷

OUR RECOMMENDATIONS

Based on the current evidence, patients on aspirin and clopidogrel who have an indication for a proton pump inhibitor or who are at risk of gastrointestinal bleeding can continue or start taking a proton pump inhibitor, including omeprazole.

Switching to another proton pump inhibitor is not currently supported by any randomized clinical trial, nor is changing to a histamine H₂-receptor antagonist. The effect of proton pump inhibitors other than omeprazole on clopidogrel is unclear, and it is not known if the interaction with clopidogrel is a class effect or specific to certain drugs of this class.¹⁸ On the other hand, we still have no compelling evidence of any major clinical interaction between alternative proton pump inhibitors and clopidogrel.¹⁸

Also, separating the dosing times of clopidogrel and omeprazole by 12 hours is not supported by any randomized clinical trial, and runs contrary to at least some ex vivo data.

It is important that all physicians assess the need for a proton pump inhibitor in their patients, as overuse of these drugs has been documented in certain settings.¹⁹

Clopidogrel and omeprazole share a common metabolic link via CYP2C19. Omeprazole, along with some other proton pump inhibitors, interacts with clopidogrel at the level of the CYP450 system. Platelet function studies show that platelet inhibition by clopidogrel is impaired, though the astute clinician should be aware of the wide variability associated with platelet function assays and clopidogrel.^1,20 However, what may appear to be an interaction at the enzymatic level does not necessarily translate into worse clinical outcomes. Additionally, reliance on nonrandomized studies rather than on randomized clinical trials can be misleading.