Sanofi-Aventis and Bristol-Myers Squibb could see a rise in sales of their blockbuster Plavix after a new study claims that patients treated for heart attacks with drug-coated stents have a much higher risk of death if treatment with the bloodthinner is stopped.

Researchers working on the study, which has been published in the Journal of the American Medical Association, looked at the medical records of 3,137 with acute coronary syndrome discharged from 127 Veterans Affairs hospitals in the USA between October 2003, and March 2005, with posthospital treatment with Plavix (clopidogrel). They observed “a clustering of adverse events” in the initial 90 days after stopping clopidogrel, supporting the possibility of a Plavix “rebound effect”.

The study also notes that that the rate of heart attack and death during the three months following cessation of Plavix therapy were significantly higher. The researchers wrote that “even though the absolute event rates were low, the relative increase in adverse events in the early period after stopping treatment with clopidogrel was nearly twofold higher than later periods".

They added that the findings "do not necessarily offset the benefits of clopidogrel therapy" and suggested that “one consideration would be to continue clopidogrel for an extended period or indefinitely, like aspirin, to avoid the potential rebound effect".

This suggestion is in line with guidelines recently issued by the American Heart Association and the American College of Cardiology which says that drug-coated stent patients should stay on Plavix for at least a year.