Genetic testing can help determine whether heart surgery patients benefit from the popular anti-platelet drug clopidogrel, which has been effective for some but carries major risks, a study published Tuesday said.
The drug is marketed under the brand name Plavix by Bristol-Meyers Squibb in the United States and Sanofi-Aventis in France.
Clopidogrel, among the most commonly prescribed medications, has been shown to reduce cardiovascular problems in patients undergoing heart procedures like balloon angioplasty or stent placement to open narrowed coronary arteries.
But scientists said there is a great degree of variation in how patients respond to the drug, which can be predicted by a genetic test which measures the presence of a particular enzyme in the blood.
The authors of a study appearing in the Journal of the American Medical Association said that analysis of existing data suggest that the pharmacologic effect of the drug varies based on variations of the gene CYP2C19.
"There is a large degree of interindividual variability in the pharmaco-dynamic response to clopidogrel," wrote the authors, researchers with the Harvard Medical School and the Brigham and Women's Medical Center.
The study in the October 27 issue of JAMA analyzed data from previously published studies on the use of clopidogrel, and found that patients who have common genetic variants of a certain gene and who also undergo a coronary stent placement have an increased risk of blood clots or other heart related complication.
"Common genetic variants in the CYP2C19 gene are associated with almost one in three patients not receiving ideal protection from ischemic events when treated with standard doses of clopidogrel for PCI" or percutaneous coronary intervention -- procedures such as the heart stent placement surgery, the authors of the study concluded.
"Given how widely clopidogrel is used to treat patients with cardiovascular disease, determination of the optimal antiplatelet treatment doses or regimens for individual patients is needed to tailor therapy appropriately," they wrote.
The research compiled nine separate studies involving 9,685 patients (of whom 91.3 percent underwent PCI and 54.5 percent had an acute coronary syndrome, the authors of the study wrote.