Paul A. Gurbel, MD, is board certified in interventional cardiology, internal medicine and cardiovascular disease. He is director of Interventional Cardiology and Cardiovascular Medicine Research at the Inova Heart and Vascular Institute, professor of medicine at the Johns Hopkins University School of Medicine and adjunct professor of medicine at Duke University School of Medicine. Read Dr. Gurbel’s profile.
The drug clopidogrel, also known by the brand name Plavix, is commonly prescribed to patients with heart problems – and for good reason. The medication prevents blood cells known as platelets from forming clots that could cause a heart attack or stroke.
It works very well to prevent heart attacks and blood clots in most patients with coronary artery disease. Unfortunately, some patients don’t respond well to the drug.
Over the last 15 years, my colleagues and I have been studying the anti-clotting properties of clopidogrel in my lab. We have identified genetic changes, or mutations, that help to predict whether a person will do well on clopidogrel. After years of exploring this link, I’m thrilled that Inova is offering a new test to quickly determine a patient’s genetic makeup to see if he or she is a good candidate for the drug.
Clopidogrel must be activated by an enzyme in the liver in order to work. But about 30 percent of people have a genetic mutation that results in an inactive form of that enzyme.
Research in my lab has shown that people with one mutation of that gene will have a poorer response to clopidogrel than people who don’t. People with mutations in both copies of the gene will have an even worse response. In a test tube, their platelets clump together more easily than those without mutations.
In real life, that translates to a higher risk of serious clotting events. For instance, in patients who have had a stent placed to treat coronary artery disease, those with two altered copies of the gene have about 4 to 5 times the risk of developing a clot within 6 months to a year, compared to people without mutations.
Fortunately, we have alternative drugs to prescribe to people who don’t respond to clopidogrel. But those drugs have a higher risk of serious bleeding. For that reason, clopidogrel is usually the first choice in patients undergoing elective heart procedures. Now we can better determine whether the patient will respond to it.
Until now, the only way to test whether someone would respond to clopidogrel was with a blood test. But the results could take days or even a week to get back – a delay that could be dangerous in patients at high risk of complications from coronary artery disease.
This year, we started offering a new test to our patients receiving cardiac catheterization at Inova Fairfax Hospital. Instead of drawing blood, we collect a DNA sample by swabbing inside the patient’s cheek. Then we analyze those cells to test for the gene in question, right at their bedside.
We have results within an hour, so we can immediately start treating patients with the drug that will work best given their genetic makeup.
Eventually we hope to expand this option to all of Inova’s hospitals. Instead of simply assuming that clopidogrel will work for a patient, we can now take our cues directly from the patient’s genes. It’s a natural next step in Inova’s mission of offering personalized, tailor-made care for every patient.
Learn more about the award-winning team at the Inova Heart and Vascular Institute.