Left ventricular assist devices (LVADs) help the heart pump blood to the rest of the body in patients who have advanced heart failure. There are currently two LVADs approved by the U.S. Food and Drug Administration (FDA): the HeartMate II Left Ventricular Assist System manufactured by Thoratec Corporation and the HeartWare Ventricular Assist System HVAD manufactured by HeartWare, Inc. In a safety alert issued Wednesday, the U.S. Food and Drug Administration (FDA) notified health care providers, patients and caregivers of serious adverse events associated with these devices.
Bleeding complications have been reported with both LVADs, the FDA reported. The notification stated that “The cause of bleeding complications is not fully understood, but is likely due to many different factors. One possible factor may be modification to blood thinning (anticoagulation) therapy in an attempt to lower the risks of pump thrombosis and embolic stroke.”
The two approved indications for LVADs are bridge-to-transplant (BTT) and destination therapy (DT). BTT is intended for patients at risk of imminent death from non-reversible left ventricular heart failure; the device helps pump blood throughout the circulatory system until a donor heart becomes available. Thoratec’s HeartMate II and HeartWare’s Ventricular Assist System were approved for BTT in 2008 and 2012, respectively. DT lends circulatory support to patients with end-stage left ventricular heart failure who are not candidates for a heart transplant. The HeartMate II was approved for DT in 2010.
The agency reported that Thoratec’s HeartMate II was associated an elevated rate of pump thrombosis (blood clots inside the pump) and HeartWare HVAD was linked to a high rate of stroke since the devices were approved.
The FDA warns that HeartMate II has been associated with a higher rate of pump thrombosis, or blood clots inside the pump. The agency states that this increase has been identified through “reports and information from a variety of sources”. Furthermore, evidence suggests that the pump thrombosis is occurring earlier than predicted by clinical trials. Two analyses showed that the rate of pump thrombosis with the HeartMate II was as high as 8.4 percent of implanted devices at 3 months and 6 percent of implanted devices at 6 months. In comparison, data from a BTT clinical trial showed that 1.6 percent of implanted devices had pump thrombosis at one year and a DT trial indicated a rate of 3.8 percent of implanted devices at two years.
The HeartWare HVAD was associated with an increased risk of stroke, the FDA said. The agency pointed to a clinical trial determining whether the HeartWare HVAD is safe and effective for DT, which it is currently not approved to treat; 28.7 percent of HVAD patients experienced one or more strokes over two years compared to 12.1 percent of the patients implanted with HeartMate II, the control device.