Two models of Implantable Left Ventricular Assist Devices (LVADs) have been pointed out by the FDA on account of possible effects including an increased rate of blood clots, stroke, and bleeding complications.
Healthcare providers, patients, and caregivers are advised to watch out for related symptoms and weigh the benefits and risks, the FDA said.
The HeartMate II Left Ventricular Assist System, manufactured by Thoratec Corporation, was associated with pump thrombosis, or blood clots inside the pump itself. The HeartWare Ventricular Assist System HVAD manufactured by HeartWare Inc. was linked to a high rate of stroke. Both devices have been associated with bleeding complications.
LVADs are used when a patient has advanced heart failure requiring a blood pump implanted in the left ventricle.
The two brands listed above are both implantable LVADs approved by the FDA. Both use a power pack and controller which are carried by the patient outside the body and connect to the blood pump.
According to the FDA, a variety of sources have reported an increase in the rate of pump thrombosis in patients using the Heart Mate II. Some pump thrombosis was observed during the clinical trials conducted to submit the product for approval in 2008 (for bridge-to-transplant) and 2010 (for destination therapy), but reported instances are occurring earlier than predicted. Two scientific analysis report the pump thrombosis rate as high as 8.4 percent of devices after three months, compared to 1.6 percent over one year during the bridge-to-transplant trial and 3.8 percent after two years during the destination therapy trial.
The FDA has been working with Thoratec to understand the higher-than-expected rate, although they have not found any “discrete, device-specific reasons” for the reported numbers. Thoratec itself is also conducting a study to identify the related risk factors.
A recently reported clinical trial of the HeartWare HVAD showed a higher likelihood for strokes than expected. According to the trial, 28.7 percent of patients implanted with the device experienced one or more strokes over two years of use, compared to 12.1 among patients using a control device (the HeartMate II.)
The FDA continues to perform clinical investigations of the device, taking into account the risks. HeartWare is also conducting a study designed to see whether blood pressure management can help lower the chances for a stroke in patients with an HVAD.
Both decides have also been reported as the cause of bleeding complications, although, the FDA said, the cause of such complications is not precisely known and probably involves many different variables.
“When used for the currently approved indications in appropriately selected patients, we believe the benefits of these LVADs continue to outweigh the risks,” the FDA wrote. They emphasized the importance of LVADs, but encouraged users to assess the benefits and risks of the device through thorough clinical evaluation, as well as taking into account potential complications.