VIDEO: No short-term link found between PPIs, myocardial infarction

In the late 2000s, several large epidemiologic studies suggested that proton pump inhibitors (PPIs) increase the risk for MI in users of clopidogrel. There was a proposed mechanism: PPIs competitively inhibit cytochrome P450 isoenzymes, which blocked clopidogrel activation and, ex vivo, increased platelet aggregation. It sounded scary – but fortunately, some reassuring data quickly emerged. In 2007, the COGENT trial randomized patients with cardiovascular disease to a PPI/clopidogrel versus a placebo/clopidogrel combination pill. After 3 years of follow-up, there was no difference in rates of death or cardiovascular events. In the glaring light of this randomized controlled trial data, earlier studies didn’t look so convincing.

So why won’t the PPI/MI issue die? In part because COGENT was a relatively small study. It included 3,761 patients, but the main result depended on 109 cardiovascular events. Naysayers have argued that perhaps if COGENT had been a bigger study, the result would have been different.

In this context, the epidemiologic study by Suzanne Landi and her associates provides further reassurance that PPIs do not cause MI. Two insurance cohorts comprising over 5 million patients were used to compare PPI users with histamine₂-receptor antagonist users after adjusting for baseline differences between the two groups. The large size of the dataset allowed the authors to make precise estimates; we can say with confidence that there was no clinically relevant PPI/MI risk in these data.

Can we forget about PPIs and MI? These days, my patients worry more about dementia or chronic kidney disease. But the PPI/MI story is worth remembering. Large epidemiologic studies are sometimes contradicted by subsequent studies and need to be evaluated in context.

Daniel E. Freedberg, MD, MS, is an assistant professor of medicine at the Columbia University Medical Center, New York. He has consulted for Pfizer.