Clotting, Stroke, Bleeding Risk with Implantable Left Ventricular Assist Devices

The FDA is alerting health care providers, patients, and caregivers about serious adverse events associated with Left Ventricular Assist Devices (LVADs). These adverse events include an increased rate of pump thrombosis (blood clots inside the pump) with Thoratec’s HeartMate II and a high rate of stroke with the HeartWare HVAD since approval of the devices. The FDA is also aware of bleeding complications associated with both devices.


Implantable LVADs help the left ventricle (the main pumping chamber of the heart) circulate blood throughout the body in patients with advanced heart failure. The devices consist of a blood pump, power pack and controller. The blood pump is implanted inside a patient’s body and attached to the heart’s left ventricle and to the aorta. The power pack and controller are connected to the blood pump and carried by the patient outside the body.


LVADs are approved for bridge-to-transplant (BTT) or destination therapy (DT). BTT refers to providing circulatory support to a patient at risk of imminent death from non-reversible left ventricular heart failure until a donor heart becomes available for a heart transplant. DT refers to providing circulatory support to a patient with end-stage left ventricular heart failure who is not a candidate for a heart transplant.


To date, there are two implantable LVADs approved by the FDA:


  • The HeartMate II Left Ventricular Assist System manufactured by Thoratec Corporation, approved for BTT in 2008 and DT in 2010
  • The HeartWare Ventricular Assist System HVAD manufactured by HeartWare, Inc., approved only for BTT in 2012


The FDA is aware of serious adverse events associated with both devices.


The FDA has received reports and information from a variety of sources indicating an increase in the rate of pump thrombosis events in patients implanted with the HeartMate II. Pump thrombosis is a serious complication that can require repeated surgery to replace the pump or can lead to death. Information also shows that patients are experiencing pump thrombosis events earlier than observed during the clinical trials conducted to support the product’s approvals in 2008 (BTT) and 2010 (DT). For example, two analyses in the scientific literature reported the confirmed (after explant) HeartMate II pump thrombosis rate as high as 8.4% of implanted devices at three months and 6% of implanted devices at six months. This is compared to 1.6% of implanted devices at one year during the BTT clinical trial and 3.8% of implanted devices at two years during the DT clinical trial.


Regarding the HeartWare HVAD, the FDA is aware of recent results from a clinical trial designed to evaluate the safety and effectiveness of this device when used for the DT indication. Investigators reported 28.7% of HeartWare HVAD patients experienced one or more strokes over two years, compared to 12.1% among patients implanted with the control device (HeartMate II). Although the HeartWare HVAD is not currently approved for DT, it is the same device approved for the BTT indication. Stroke is a serious complication that can lead to permanent patient disability and death.


The FDA is aware of bleeding complications related to both the Thoratec HeartMate II and HeartWare HVAD through adverse event reports and information from a variety of sources. Bleeding is a serious complication that can lead to death. 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 FDA recognizes that LVADs are life-sustaining, life-saving devices for patients with advanced left ventricular heart failure. When used for the currently approved indications in appropriately selected patients, the benefits of these LVADs continue to outweigh the risks. However, the FDA also believes it is important for health care providers and patients to be aware of this important information when considering the use of these devices and clinical management of their patients.


Health care providers should perform a thorough clinical evaluation, assessing the benefit-risk profile of each patient in determining the most appropriate treatment plan and, if necessary, selecting a device. They must consider the risks for pump thrombosis, stroke, and bleeding when determining the appropriate therapy for individual patients and review the current device labeling prior to making treatment decisions if using either of these devices.


The FDA has extensively evaluated all available information, including adverse event reports received by the FDA, data from Thoratec, data from the scientific literature, and data from the Interagency Registry for Mechanically Assisted Circulatory Support. The analysis did not identify discrete, device-specific reasons for the reported rise in pump thrombosis. The FDA acknowledges the risks of pump thrombosis for HeartMate II have increased since the time of approval. However, careful review of all available data suggests the benefits of the device, when used in an appropriately selected patient, continue to outweigh the risks for the currently approved indications.


Thoratec is currently conducting a prospective, multi-center, non-randomized study designed to assess the incidence of HeartMate II pump thrombosis and to identify the risk factors associated with pump thrombosis events. Details of this study can be found on the National Institutes of Health website.


The FDA is concerned about the reported stroke rates associated with the HeartWare HVAD but at this time, believes the benefits of using the device continue to outweigh the risks for the currently approved BTT indication. The FDA also believes it is appropriate to continue the clinical investigation of this device in the DT population with the careful monitoring procedures currently in place.


HeartWare is currently conducting a prospective, randomized, controlled, un-blinded, multi-center study to assess whether optimal blood pressure management can help lower the incidence of stroke in DT patients implanted with an HVAD. Details of this study can be found on the National Institutes of Health website. 


See the FDA Safety Communication


See also Medical Law Perspectives, July 2015 Report: Organ Transplants: Saving Lives, Facing Risks, Minimizing Complications


See also Medical Law Perspectives, February 2015 Report: Mending a Broken Heart: Malpractice Risks in Diagnosing and Treating Heart Disease


See also Medical Law Perspectives, February 2014 Report: Congenital Heart Conditions: How Infants, Adults, and Healthcare Providers Handle the Risks


See also Medical Law Perspectives, December 2013 Report: Thicker Than Water: Liability When Blood Clots Cause Injury or Death