FDA Warns of Serious Adverse Events Linked to LVADsAug 6, 2015
The U.S. Food and Drug Administration (FDA) has issued a safety alert warning of serious adverse events related to left ventricular assist devices (LVADs). These devices are implanted in patients with advanced heart failure to help the left ventricle of the heart pump blood to the rest of the body. According to the alert, the only FDA-approved LVADs on the market are the HeartMate II Left Ventricular Assist System manufactured by Thoratec Corporation and the HeartWare Ventricular Assist System HVAD manufactured by HeartWare, Inc.
One of the approved uses for LVADs is bridge-to-transplant (BTT), which 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 was approved for this purpose in 2008, and HeartWare's Ventricular Assist System was approved for BTT in 2012. LVADs are also approved for destination therapy, which provides circulatory support to patients who are not candidates for a heart transplant suffering from end-stage left ventricular heart failure. Thoratec's LVAD was approved for DT in 2010.
The FDA is notifying health care providers, patients and caregivers that LVADs have been linked to serious adverse events, including bleeding complications with both devices that are on the market. The safety alert 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 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.
According to the safety alert, the FDA received reports showing that the rate of pump thrombosis with HeartMate II has increased. Additionally, data indicates that this complication is occurring earlier than in clinical trials. A BTT clinical trial showed that 1.6 percent of implanted devices had pump thrombosis at one year and 3.8 percent of implanted devices at two years for a DT trial. However, two analyses in the scientific literature suggest that these figures are underestimations; the pump thrombosis rate for HeartMate II was as high as 8.4 percent of implanted devices at 3 months and 6 percent of implanted at 6 months.
The FDA safety alert also cited data from a clinical trial used to study whether the HeartWare HVAD is safe and effective for DT, which it is currently not approved to treat. According to the FDA notification, investigators found that 28.7 percent of HVAD patients experienced one or more strokes over two years. Comparatively, 12.1 percent of the patients implanted with HeartMate II, the control device, experienced one stroke or more over two years.