Pradaxa, the first drug to gain approval as part of a new generation of blood thinners to lower stroke risk, was associated with an increased risk of heart attack in a new study published last Monday.
According to WebMD, Patients taking the new anti-clotting drug Pradaxa have a 33% higher risk of heart attack or severe symptoms of heart disease than do patients taking warfarin.
Pradaxa, marketed by Boehringer Ingelheim GmbH, was approved in the U.S. in 2010 to treat atrial fibrillation—an irregular heartbeat that puts people at higher risk of developing blood clots. Such clots can be fatal if they travel to the lungs or the brain where they can cause a stroke.
The new study findings, from Cleveland Clinic researchers Ken Uchino, MD, and Adrian V. Hernandez, MD, PhD, is based on data from seven clinical trials that enrolled 30,514 patients.
“The risk of [heart attack] or acute coronary syndrome is increased with [Pradaxa] compared with various control treatments, which include adjusted-dose warfarin, [Lovenox], or placebo,” Uchino and Hernandez conclude.
Acute coronary syndrome — acute symptoms of serious heart disease — is usually caused by the rupture of a plaque in a heart artery.
The FDA has launched a safety investigation into Pradaxa side effects along with the manufacturer, Boehringer Ingelheim. The investigation will look into hundreds of Pradaxa bleeding deaths reported worldwide since its release.
According to the Institute of Safe Medication Practices (ISMP), the quarterly drug safety report just released that in the first quarter of 2011, the number of reported bleeding problems with Pradaxa outnumbered those associated all other drugs monitored by the group.
The ISMP report indicates that there were a total of 932 serious adverse events reported involving Pradaxa problems between January and March 2011. Those reports included 120 deaths, 25 incidents where people were permanently disabled by the drug, 543 incidents of hospitalization and 505 reports of Pradaxa hemorrhages, or internal bleeding.
Yet, even with these reports, the researchers still believe the benefits outweigh the risks.
“These additional concerns deserve serious consideration in weighing the risks and benefits of [Pradaxa],” Redberg concludes.
Despite the apparent increase in heart attack risk, Uchino and Hernandez note that the benefits of Pradaxa — particularly its ability to prevent stroke in patients with atrial fibrillation — outweigh its risks.
And they note that while the risk of heart attack or acute coronary syndrome is higher in patients on Pradaxa than in those on warfarin, the actual risk of these events is increased by only 0.25% per year.
That’s still an important added risk for patients who may already be piling up risk factors for heart disease, says Kirk Garratt, MD, clinical director of interventional cardiology research at New York’s Lenox Hill Hospital.
“If I have a patient on this drug for 10 years, I’d expect a 5% increased lifetime risk of heart attack,” Garratt tells WebMD. “The most important aspect of this study is that it allows us to see a consistent risk across studies and types of patients. That speaks to the conclusion that this study is well done and that the risk is real.”