According to a study published in the Journal of the American Medical Association, patients who stop using Plavix (clopidogrel) may be at increased risk of a heart attack and death in the first three months following cessation of the drug. The study was done by the University of Colorado and Denver Veteran’s Affairs Medical Center and involved over 3,000 participants from 127 VA hospitals across the U.S.

Data analysis included patients who were treated at participating hospitals between October 2003 and March 2005. Study groups included those treated medically and those who underwent percutaneous interventions. Both groups showed dramatic increase in incidence of myocardial infarction and death in the first 90 days following cessation of clopidogrel therapy, as compared to the period after the first three months.

Although researchers are not sure at this time what may be the exact cause of this phenomenon, one theory suggests a rebound effect. Plavix (clopidogrel) is a powerful blood thinner which suppresses platelets. It may be possible that, once the medication is withdrawn, the body responds to the decreased numbers of platelets by over-producing them. Researchers agree that more extensive studies need to be done, to determine the validity and cause of these findings.