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VIDEO: HeartMate 3 LVAD solves pump thrombosis

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Some big issues remain for HeartMate 3

By eliminating all episodes of pump thrombosis during 6-month follow-up, the HeartMate 3 appeared to resolve one of the major issues that has stood in the way of patients and physicians feeling comfortable with left ventricular assist devices. The smaller size of the HeartMate 3 pump and its ability to be placed with minimally invasive and fairly rapid surgery is another big advance, putting this device on par with the rival pump, the HeartWare HVAD.

But the performance of the HeartMate 3 left ventricular assist device (LVAD) in MOMENTUM 3 also highlighted the shortcomings that still remain for these devices: the unchanged rates of stroke, gastrointestinal bleeds, and infections with HeartMate 3, compared with HeartMate II in this trial, and similar 6-month survival rates in the two arms of the study.
The HeartMate 3 can be implanted without sternotomy, using an 8 cm incision on the lateral chest wall, resulting in a shorter postoperative stay and fewer perisurgical adverse events. Despite the less invasive surgery and absence of pump thrombosis, some patients and physicians will remain hesitant to use an LVAD unless it is unavoidable because of concern about strokes. Until further design and procedural refinements change the rate of serious strokes and other adverse events, LVADs will not be fully competitive with heart transplantation.

The competition between HeartMate and the HeartWare devices will help drive this field forward, leading to further improvements in outcomes and expanded LVAD use.

Mark Slaughter, MD, is professor of surgery and chairman of cardiovascular and thoracic surgery at the University of Louisville (Ky.). He was an investigator in MOMENTUM 3, he has been a consultant to EvaHeart and Oregon Heart, and he has received research support from Carmat and HeartWare. He made these comments as designated discussant for the report and in a video interview.

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– HeartMate 3, the latest left ventricular assist device in the HeartMate line, appears to have solved the problem of pump thrombosis, a complication that has dogged ventricular pumps since the issue leapt into medical awareness about 3 years ago (New Engl J Med. 2014 Jan 2;370:33-40).

During 6 months of follow-up, none of 152 heart failure patients assigned to receive a HeartMate 3 left ventricular assist device (LVAD) developed suspected or confirmed pump thrombosis, compared with 14 patients (10%) having pump thrombosis out of 138 recipients of the prior-generation HeartMate II LVAD who served as the control group for the study.

Dr. Mandeep R. Mehra Mitchel L. Zoler/Frontline Medical News

Dr. Mandeep R. Mehra

This sharp cut in pump thrombosis episodes directly drove a similar, clear drop in reoperations for pump malfunction (1% in the HeartMate 3 group and 8% with HeartMate II) that in turn drove the study’s primary, 6- month endpoint, a composite of survival without a disabling stroke or need for additional surgery to remove or replace the pump, Mandeep R. Mehra, MD, said at the American Heart Association scientific sessions.

“Three years ago, when the issue of pump thrombosis was first revealed, there was a lot of consternation and some drop in LVAD use, especially as destination therapy. We think that seeing no pump thrombosis whatsoever will give people renewed confidence in this technology,” said Dr. Mehra, professor of medicine at Harvard Medical School and medical director of the Heart and Vascular Center of Brigham and Women’s Hospital, both in Boston.

Pump thrombosis has also been a problem for the patients who have received a competitor LVAD, the HeartWare HVAD device (Circulation. 2015 Nov 10;132[suppl 3]:A19675), approved for U.S. use as bridge to transplant. HeartMate II is approved for both bridge to transplant and for destination therapy.

In addition to apparently eliminating pump thrombosis, HeartMate 3’s size and potential implantation approach should make its placement during routine use as quick and minimally invasive as the HeartWare device, features that should further help broader use of HeartMate 3, commented Mark Slaughter, MD, professor and chairman of cardiovascular and thoracic surgery at the University of Louisville (Ky.). But Dr. Slaughter and others were also quick to highlight the shortcomings that remain with both devices that will continue to hamper a broader role for LVAD treatment of patients with advanced heart failure.

Dr. Nancy K. Sweitzer speaks during the 2016 AHA Scientific Sessions Mitchel L. Zoler/Frontline Medical News

Dr. Nancy K. Sweitzer

“The rates of stroke, infection, and gastrointestinal bleeding were not changed” with HeartMate 3 compared with HeartMate II, complications that “account for more events than pump thrombosis,” commented Nancy K. Sweitzer, MD, PhD, professor of medicine and director of the Sarver Heart Center of the University of Arizona, Tucson. “Pump thrombosis is a horrible complication,” so eliminating it is a step forward, “but we must also deal with these other complications before LVADs are widely accepted as an alternative” to heart transplantation, she said in an interview. Dr. Sweitzer especially cited the persistently high stroke rate, with a disabling stroke rate of 6% in patients who received a HeartMate 3 and 4% in those who received a HeartMate II during 6-month follow-up in the trial, a difference that was not statistically significant.

“We thought that if there was less pump thrombosis we’d see less stroke, but that is not what the data suggest. It’s the big puzzle we need to figure out before we see widespread acceptance of this treatment,” Dr. Sweitzer said.

“This will not shift LVAD use substantially,” commented Christopher B. Granger, MD, a professor of medicine and a heart failure specialist at Duke University, Durham, N.C. “Reducing the need for reoperation is good for the field, and is an incremental advance, but it is not transformational,” he said in an interview.

The MOMENTUM 3 (Multicenter Study of MagLev Technology in Patients Undergoing Mechanical Circulatory Support Therapy with HeartMate 3) trial randomized 294 patients at 69 U.S. centers. The study’s primary endpoint of 6-month survival free from disabling stroke or reoperation to repair or replace the LVAD occurred in 86% of 152 patients who received a HeartMate 3 and 77% of 142 patients randomized to HeartMate II, a statistical difference that met the prespecified criteria for both noninferiority and superiority. Concurrently with Dr. Mehra’s report at the meeting, a journal article appeared online (New Engl J Med. 2016 Nov 16. doi: 10.1056/NEJMoa1610426). He stated that as far as he understood, St. Jude would submit the 6-month data he reported to the Food and Drug Administration in an application for marketing approval for HeartMate 3.

“I agree that there are still morbid evens [with HeartMate 3] that need to be surmounted, but this is a confidence-building step in the right direction,” Dr. Mehra said.

On Twitter @mitchelzoler

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