Blood-Thinning Drugs Raise Alarm in Stroke Victims

ByABC News
January 5, 2006, 9:49 PM

Jan, 6, 2006 -- -- The sudden and severe bleeding stroke suffered by Israeli Prime Minister Ariel Sharon may be raising concern among stroke patients worldwide.

Israeli doctors reportedly are fielding calls from concerned patients who take anti-clotting medications, similar to the drugs Sharon was taking before his latest stroke, and now fear they too are at risk. Anti-clotting drugs are used by millions of people to help lower the risk of blood clots and blocked blood vessels.

Ironically, however, the very drugs that can prevent one type of stroke -- the blocking or ischemic variety -- can lead to a higher risk of another -- the bleeding kind.

Sharon reportedly had been taking the anti-clotting drug Clexane after suffering a blood-clot-related stroke in mid-December. Clexane is in a class of anti-clotting drugs believed to be stronger than aspirin, yet not quite as potent as the thinner Coumadin. Clexane is sold in the United States under the name Lovenox.

Sharon was on Clexane while waiting to be treated for a hole in the chambers of his heart that was diagnosed after his stroke last month. The hole, called a patent foramen ovale, or PFO, is a common birth defect that experts say occurs in 10 percent to 20 percent of the population.

Dr. Ron Waksman, associate director of cardiology at Washington Hospital Center, says most people live long and healthy lives without any knowledge or sign of this heart defect, though for some, PFOs are thought to increase the risk of stroke related to blood clots, called embolic strokes. PFO-related strokes of this kind affect more than 80,000 people every year in the United States alone.

It is unclear how much of a role blood-thinning medications played in Sharon's life-threatening stroke.

PFOs do not always need to be fixed. However, most patients who have had embolisms and are having procedures to seal their PFOs take some type of blood thinner to prevent further clots, Waksman said.

"They go on blood thinners as soon as possible after the embolism, and they are kept on them till they [doctors] close the hole. Or until shortly before the procedure," he said.

Unfortunately, the benefits of blood-thinning drugs sometimes come with dangerous complications.

"All of these therapies carry the risk of hemorrhage, but it is just a little less than 2 percent per year. Patients on these drugs should not be alarmed. The risk of this type of bleeding is rare," said Dr. J.P. Mohr, director of the Stroke Center, Columbia University-Presbyterian Medical Center. "Patients should be aware that 2 percent is small, but it is not zero."

For the millions of patients taking Coumadin, aspirin and other blood thinners, Mohr and Waksman stressed the importance of taking the right dose and being under constant medical care, so the risks and benefits were properly balanced.

"People should know if they are getting the right amount of blood thinners. They should be monitored carefully. Blood should be tested every week, or month depending on each individual patient," Waksman said.