April 25, 2012
Stroke Risk High When Anti-Clotting Drugs Stopped
Some patients with irregular heartbeats who are taken off anti-clotting medication face a high risk of stroke or blood clotting within a month, according to new research presented at the American Heart Association's Emerging Science Series webinar.
Patients with certain types of atrial fibrillation, or irregular heartbeat, take these drugs to reduce the risks of clots that could lead to a stroke. Sometimes they are instructed to stop taking the medication temporarily before surgery or permanently because of side effects.
"No matter what drug they are on, patients who need anticoagulation revert back to their intrinsic risk of stroke and embolism after discontinuation, so it shouldn't be done lightly," said Manesh Patel, M.D., lead author and assistant professor of medicine at the Duke University School of Medicine. "Unfortunately, it's unclear how to provide optimal anti-coagulation coverage during periods of transition."
Researchers analyzed data from a clinical trial known as ROCKET AF, finding the risk is similar whether patients are taking the drug warfarin or the newer anticoagulant rivaroxaban. Rivaroxaban is taken once daily and doesn't require the frequent monitoring of warfarin, which requires frequent dose-adjustment.
In ROCKET AF, rivaroxaban was found to be as effective as warfarin in preventing stroke and blood clots in more than 14,000 patients with atrial fibrillation. Patients also had no greater risk of bleeding. However, concerns persisted about possible increased rates of stroke and blood clots after discontinuing rivaroxaban, which led to a warning in the prescribing information.
Because of these concerns, the researchers analyzed strokes and blood clots that occurred following temporary interruptions, and between 3 and 30 days after early drug discontinuation or the transition to warfarin at the study's end.
Strokes and blood clots occurred:
At similar rates with both drugs after a temporary interruption — 6.20/100 patient-years for those on rivaroxaban vs. 5.05/100 patient-years for those taking warfarin;
At similar rates in both drugs after permanently stopping the medicines — 25.60/100 patient-years for people taking rivaroxaban (vs. 23.38/100 patient-years for those on warfarin;
More often in the transition from rivaroxaban to open label therapy (6.42/100 patient-years) vs. warfarin (1.73/100 patient-years). However, the risk seems to be high only for stroke. There was no difference between the drugs when investigators evaluated all blood clot-related events (including strokes, heart attack and vascular death) within 30 days of stopping medication.
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