The approval of the HeartMate II, the continuous-flow left ventricular assist device, has been expanded to include its use as destination therapy for people with severe heart failure who are not acceptable candidates for heart transplantation.
The device can now be used in patients with New York Heart Association class IIIB or IV end-stage left ventricular failure, who have received optimal medical therapy for at least 45 of the last 60 days, according to the statement issued by the manufacturer, Thoratec Corp.
The Food and Drug Administration and Thoratec Corp. announced the approval of the Heart Mate II left ventricular assist device (LVAD) in late January.
It was first approved by the FDA in April 2008 for use as a bridge to transplantation in cardiac transplant candidates at risk of imminent death from nonreversible left ventricular heart failure. The HeartMate II is markedly smaller than previously available devices, including Thoratec's HeartMate XVE, the only other LVAD approved for destination therapy. The HeartMate XVE, a pulsatile flow LVAD, was first approved for use as a bridge to transplantation.
“Its smaller size and mobility should allow more patients, including women and men of smaller stature, access to treatment,” Dr. Jeffrey Shuren, director of the FDA's Center for Devices and Radiological Health, said in the agency's approval statement.
The HeartMate II Destination Therapy study, a randomized trial sponsored by Thoratec, compared the HeartMate II with the HeartMate XVE in 200 patients (median age 64 years) with advanced heart failure who were ineligible for cardiac transplantation. The primary end point—survival at 2 years free of disabling stroke and reoperation to repair or replace the device—was met by 62 (46%) of the 134 patients who received the Heart Mate II, compared with 7 (11%) of the 66 who received the HeartMate XVE (N. Engl J. Med. 2009;361:2241-51).
“In addition, data collected in a separate registry of smaller-stature women and men indicated that the device worked well in this specific population,” the FDA statement said.
As a condition of FDA approval, Thoratec is required to conduct a postmarketing study evaluating the device's performance. The data will be entered into the Interagency Registry of Mechanically Assisted Circulatory Support (INTERMACS), which is managed by the FDA; the National Heart, Lung, and Blood Institute; the Center for Medicare & Medicaid Services; and participating hospitals and manufacturers. The study will follow 247 patients for 2 years, and will collect data on outcomes, adverse events, functional status, and quality of life, according to Thoratec.
My Take
Smaller Device Yields Big Results
With this approval, the current state-of-the-art nonpulsatile LVAD can be offered to all appropriate patients without the confines of an investigational study. The approval validates the concept that the smaller LVAD devices confer benefits, compared with the pulsatile device, and it opens up the way to their further development.
Small-stature adults, and many women, are too small for the HeartMate XVE. The HeartMate II is a smaller, nonpulsatile pump, so more patients are eligible candidates. And as the HeartMate II Destination Therapy study showed, there's less morbidity associated with the surgical operation because of the smaller size, which is a big advantage.
Despite better survival and fewer infections with the HeartMate II compared with the HeartMate XVE, the stroke rate was not different, and that's a concern. Investigators will focus more on the mechanisms behind stroke and the resultant anticoagulation strategies.
Typically, destination-therapy patients have class IV heart failure, a low ejection fraction, and poor exercise tolerance, but are not transplant candidates—perhaps because they have had cancer recently, are too old, or have other comorbidities.
Efforts are underway at the NHLBI to study VAD therapy in less ill patients, to determine if patients can be identified as candidates for LVAD therapy before they get desperately ill and need a transplant, or before they are as sick as current LVAD candidates. The HeartMate XVE has shown wear and tear after 1–1½ years of use, but there are people who have had the HeartMate II for more than 3 years.
Considering how far we have come with cardiac resynchronization therapy devices and implantable cardioverter defibrillators—which once were huge, bulky devices that have gotten smaller and smaller and eventually will not even have leads—this is certainly what we expect to happen with LVADS as well.