WEDNESDAY, Jan. 28 (HealthDay News) -- Heart attack patients who take both clopidogrel and a proton pump inhibitor other than pantoprazole have an increased risk of reinfarction and may lose the beneficial effects of clopidogrel, according to research published online Jan. 28 in CMAJ, the Canadian Medical Association Journal.
David N. Juurlink, M.D., Ph.D., of Sunnybrook Health Sciences Centre in Toronto, Ontario, Canada, and colleagues performed a case-control study of patients aged 66 and older who started taking clopidogrel between April 2002 and December 2007 after being discharged from the hospital following treatment for acute myocardial infarction. The patients had been readmitted to the hospital within 90 days for acute myocardial infarction.
Among 13,636 patients prescribed clopidogrel after acute myocardial infarction, the researchers identified 734 that were readmitted with myocardial infarction and 2,057 controls. After adjusting for multiple variables, they found that current use (within 30 days) of proton pump inhibitors was associated with an increased risk of reinfarction (adjusted odds ratio 1.27). There was no association between reinfarction and more distant use of proton pump inhibitors, the investigators note. In addition, pantoprazole was found to have no association with readmission for myocardial infarction (adjusted odds ratio 1.02), the report indicates.
"Depending on the prevalence of exposure to [some proton pump inhibitors], we estimate that 5 percent to 15 percent of early readmissions because of myocardial infarction among patients taking clopidogrel could be the result of this drug interaction," the authors write. "These observations support the hypothesis that some proton pump inhibitors significantly reduce or even abolish the cardioprotective effects of clopidogrel."
One co-author was previously employed by Pfizer.