Clopidogrel (Plavix) is a medicine to prevent blood clots, which can cause heart attacks and strokes. It may be prescribed after a heart attack, after angioplasty, and for people who have heart disease or peripheral arterial disease.
Some people have changes, or mutations, to a certain gene (CYP2C19). These changes may keep the body from being able to use clopidogrel to prevent blood clots. If a person with these genetic changes takes clopidogrel, the medicine may not work. This may raise the person's chance of having a heart attack or a stroke.
A genetic test might be used if your doctor thinks that your body is not using clopidogrel properly. This test checks to see if you have genes that let your body use clopidogrel. But experts aren't yet sure whether genetic changes keep clopidogrel from preventing a heart attack or stroke.
This genetic test alone is not enough to tell whether the medicine will help you. You also may have a test that shows how your body's platelets are working to clot blood. Having a platelet test after you take an antiplatelet can show if the medicine is working.
The test is done by swabbing the inside of your cheek.
Eikelboom JW, et al. (2012). Antiplatelet drugs: Antithrombotic therapy and prevention of thrombosis, 9th ed.–American College of Chest Physicians evidence-based clinical practice guidelines. Chest, 141(2, Suppl): e89S–e119S.
Holmes DR, et al. (2010). ACCF/AHA Clopidogrel clinical alert: Approaches to the FDA "Boxed Warning": A report of the American College of Cardiology Foundation Task Force on Clinical Expert Consensus Documents and the American Heart Association. Circulation, 122(5): 537–557.
Levine GN, et al. (2011). 2011 ACC/AHA/SCAI Guideline for percutaneous coronary intervention: A report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines and the Society for Cardiovascular Angiography and Interventions. Circulation, 124(23): e574–e651.
Mega JL, et al. (2010). Reduced-function CYP2C19 genotype and risk of adverse clinical outcomes among patients treated with clopidogrel predominantly for PCI: A meta-analysis. JAMA, 304(16): 1821–1830.
Paré G, et al. (2010). Effects of CYP2C19 genotype on outcomes of clopidogrel treatment. New England Journal of Medicine, 363(18): 1704–1714.
Primary Medical Reviewer
Rakesh K. Pai, MD, FACC - Cardiology, Electrophysiology
Specialist Medical Reviewer
Stephen Fort, MD, MRCP, FRCPC - Interventional Cardiology
How this information was developed to help you make better health decisions.