According to study published in the online edition of The Lancet (23rd December), researchers believe younger heart attack survivors with a common gene variation, are more likely to suffer another heart attack, death or other heart problems, if put on Plavix, which is an anti-clotting drug.
 
Often, Plavix is prescribed along with low-dose aspirin to prevent clogging of blood vessels after a heart attack, or after under-going an artery-opening stent.  However, not every patient responds well to Plavix (clopidogrel) and it is not certain why some patients respond well to it and others don’t.
 
Dr. Robert F. Storey from the Cardiovascular Research Unit, University of Sheffield School of Medicine, U.K. and author of the accompanying comment in the journal, explaining says Plavix ‘targets a very important receptor on platelets, but people vary substantially in how good an anti-clotting effect …’ the drug produces, and though other factors like age also influence a patient’s response to the drug, mostly genetics play an important role in response variations.
 
The study carried out by a team led by Dr. Gilles Montalescot from Hopital Pitie-Salpetriere, Paris collected data on 259-first heart attack patients, aged 45 and younger on Plavix.
 
Researchers found that 28% of these patients carried a gene variation called CYP2C19*2, which is quite common in the West, and far more commoner in Asia .  They noted that an average yearly follow-up revealed patients with a gene variation were three-and-a-half times more likely to die, suffer another heart attack or require additional cardiac treatment, as compared to those with no variation.
 
Further, the study also revealed all patients with CYP2C19*2, were six times more likely to have a blockage in a stent, received after suffering a heart attack.  Moreover, because of gene variation, patients who received Plavix as part of their treatment, continued to suffer from heart problems up to eight years after treatment, four times more likely to suffer additional heart problems, after being treated with the blood thinner.
 
According to Storey, rather than checking people’s genetic make-up after an heart attack to minimize the risk, far better to do a different blood test for checking their anti-clotting response to clopidogrel.
 
A couple of recent studies have also reached the same conclusion, stating the adverse reaction Plavix has on some patients.  The findings of the first study published in the Journal of the American College of Cardiology in August, reveals of the 259-patients who received Plavix as part of their treatment, the smokers had significantly less clot formation than the non-smokers.
 
The second study carried out by Austrian researchers and published in the online edition of the Journal of the American College of Cardiology in October, found anti-clogging effects of Plavix can be reduced by using calcium channel blockers drugs, widely prescribed for lowering blood pressure.
 
In conclusion, the gene known as CYP2C19 plays an important role in how individuals metabolize commonly prescribed drugs, including treatment for depression, heart disease, high blood pressure and hyperactivity.  Plavix manufactured by Sanofi-Aventis (SASY.PA) and Bristol-Myers Squibb Co. (BMY.N) drug is less effective for people with this gene variation, also raising the risk of blood clots for those who have had heart stents implants.