A set of new findings have proven wrong the earlier reports that people with a certain genetic make-up don’t benefit from the blood-thinner clopidogrel, also known as Plavix.
Previously it was reported that clopidogrel is less effective in some patients, which lead the Food and Drug Administration (FDA) in the US to issue a black box warning to physicians on the drug’s package insert.
"(Our findings) add a further layer of complexity to the FDA ‘black box’ warning and show that reported genetic variants have no effect in certain patient populations," said Guillaume Pare of the Michael G. DeGroote School of Medicine.
To assess the influence genetics might have on patients prescribed clopidogrel, Pare and colleagues from McMaster University conducted a genetic sub-study of 6,000 participants from two major clinical trials (CURE and ACTIVE).
The CURE (Clopidogrel in Unstable Angina to Prevent Recurrent Ischemic Events) trial of 12,562 patients with acute coronary syndrome in 28 countries found clopidogrel significantly reduces the risk of heart attack stroke and dying.
The ACTIVE (Atrial Fibrillation Clopidogrel Trial with Irbesartan for the Prevention of Vascular Events) trial of 7,554 patients with atrial fibrillation in 30 countries found clopidogrel added to Aspirin significantly reduced the risk of cardiovascular events, and particularly stroke.
"We found the previously reported genetic variants had no effect at all (for patients) in either the CURE or ACTIVE trials," said Pare.
He said the positive results from McMaster’s genetic sub-study come from studying different patient populations. "Also, our study design was a bit stronger from an epidemiology point of view," he added.
The findings were presented at the European Cardiovascular Society Congress meeting in Stockholm and were also published in the New England Journal of Medicine.