Genetic testing can now help predict which patients have cardiac higher doses of a common anti-coagulants, a new study is the latest example of "personalized medicine".
Doctors usually prescribe Plavix blood thinner to prevent blood clots in the heart of people who have survived heart attacks.
However, almost one third of cardiac patients have genes that prevent them from properly handle the drug, said Jessica Mega cardiologist, author of the study presented today at the annual meeting of the American Heart Association in Orlando.
Genetic testing can now identify patients with these mutations.
More importantly, the study shows that Mega triple or quadruple the typical dose of Plavix, 75 mg per day helps most people with these genes to treat substance normally.
"This is the most promising area of personalized medicine, cardiology," says Christopher Cannon of Harvard Medical School, who was not involved in the new study.
Few hospitals now perform these genetic tests, says the Mega, combined with a doctor Brigham and Women's Hospital, Harvard Medical School in Boston. But doctors could test patients 'blood' by sending in a specialized laboratory.
The findings could help patients correct dose of medication is most appropriate and not immediately after trying and failing a course of treatment, says Cam Patterson, chief of cardiology at the University of North Carolina at Chapel Hill. "You do not want to wait until you have an event to say, 'Oh, this patient is resistant to Plavix," said Patterson. "This could have a significant impact on how we treat patients."
However, note Mega his study had significant limitations. Although it appears that higher doses of Plavix, patients platelets less likely to clot, the researchers do not yet know if these doses reduce heart attack rates.
And high doses does not work for everyone. Although the triple or quadruple doses helped those who have only one copy of the gene variant, large doses are not just for those who have two copies, research shows.
The study did not examine whether higher doses actually reduce heart attack rates, Patterson said. Answering this question requires further study.
And Mega says heart patients is still monitored closely by their doctors. "You do not want patients to begin immediately to take three pills a day for them," he says.
However, Patterson says it is reassuring to see that increasing doses of Plavix seems safe. Preventing blood clots in stents - mesh scaffolds used to prop open clogged arteries - is "a matter of life or death," said Patterson.
Plavix is the third top-selling drug in the country with 6.1 billion in sales in 2010, according to IMS Health.
Plavix - also known as clopidogrel - will be available next year for the general. So, given to patients three or four pills should not be too expensive, says Patterson. Until now, patients who did not respond to normal doses of Plavix is often prescribed branded options - new medications and Effient Brilinta, says Patterson.
Mega says the findings are encouraging and point towards the day when doctors will no longer need to provide a "one size fits all" medicine. Cancer experts have the tools to customize therapy for many years, he says. For example, doctors may use genetic profiling to predict which patients with early breast cancer need chemotherapy and which can easily avoid. Cardiologists genetic tests much less.
But cardiologists involved in a unique and personal approach: cardiac stem cells.
The research presented Monday showed that cardiac stem cells - taken from patients during surgery, then reinjected into the body four months later - seems to help repair the heart muscle itself, but only modestly. The researchers caution that the study was small and preliminary, with only 23 patients, only 14 of them received the stem cells. Doctors still have to make long-term monitoring of patients suffering from heart failure, a condition in which the heart can not pump enough blood around the body. However, another study of stem cells derived from bone marrow cells has been disappointing. These cells, and of course, no benefit for patients with heart failure, showed a presentation.
However, Mega, said he hopes his findings will lead to better patient care.
"Ten years ago, when the human genome has been sequenced, there was so much enthusiasm to match," said Mega. "Now we're starting to get there."
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