Two-Year Data Presented From MOMENTUM 3 for Abbott Vascular's HeartMate 3 LVAD
March 11, 2018—Two-year follow-up data from the MOMENTUM 3 clinical trial evaluating the magnetically levitated HeartMate 3 left ventricular assist device (LVAD; Abbott Vascular) were presented by Mandeep R. Mehra, MD, in a Late Breaking Trial session at the American College of Cardiology's (ACC) 67th annual scientific session held March 10–12 in Orlando, Florida. The study findings were simultaneously published by Dr. Mehra et al online in The New England Journal of Medicine.
In August 2017, Abbott Vascular announced US Food and Drug Administration approval for the Full MagLev HeartMate 3 LVAD for the management of advanced heart failure patients in need of short-term hemodynamic support (bridge-to-transplant or bridge-to-myocardial recovery).
The 6-month outcomes for 294 patients were reported in The New England Journal of Medicine in November 2016. The current study reports outcomes for 366 patients who have completed 2 years of follow-up. Two-year follow-up results for all 1,028 patients enrolled in the trial are expected by late 2019, advised Dr. Mehra.
At 2 years of follow-up, severely ill patients with advanced heart failure who received the device, which is fully implanted in the chest, experienced no malfunctions requiring replacement or removal of the device for blood clotting. Also, their risk of a stroke was halved compared with patients who received the established version of the pump that requires an abdominal location for the implant.
In the ACC announcement, Dr. Mehra commented, "We saw a marked decrease in pump malfunction requiring reoperation, mostly driven by an absence of confirmed pump thrombosis, and a halving of observed stroke rates in patients implanted with the HeartMate 3 compared with patients who were implanted with the HeartMate II."
Dr. Mehra, who is Medical Director of the Heart and Vascular Center, Brigham and Women's Hospital in Boston, Massachusetts, noted that the HeartMate 3's fully magnetic levitation technology makes the pump frictionless, without mechanical bearings, to push blood through the device and into the aorta.
Although the trial was designed to show only noninferiority of outcomes with HeartMate 3 versus HeartMate II, the results actually demonstrated superiority of HeartMate 3.
As summarized in the ACC announcement, the MOMENTUM 3 trial enrolled 1,028 patients (78% men; median age, 60 years) at 69 centers in the United States. All patients had severe heart failure that left them unable to engage in any physical activity without discomfort. Most had symptoms of fatigue or shortness of breath even when resting. Most (85%) were receiving intravenous heart failure medication because pills alone no longer worked or caused intolerable adverse effects.
Some patients in the study needed an LVAD to sustain them until they were able to receive a heart transplant. Others, because of age or other health problems, were not candidates for a transplant and relied on an LVAD as lifelong therapy.
Patients were randomly assigned to be surgically implanted with either HeartMate II or HeartMate 3. All patients received anticoagulant medications after surgery. The primary study endpoint was the combined rate of disabling stroke, device malfunction requiring surgery to replace or remove it, and death from heart failure.
Dr. Mehra reported that 82.8% of HeartMate 3 patients were alive at 2 years, compared with 76.2% of HeartMate II patients. One percent of HeartMate 3 patients needed additional surgery to remove or replace the device (because of an electrical or mechanical malfunction), compared with 17% of HeartMate II patients (two-thirds of which were for pump clotting).
HeartMate 3 patients were also less likely to have a stroke than HeartMate II patients (10% vs 19%). However, the rate of disabling stroke, defined as a stroke resulting in severe inability to walk or attend to bodily needs without assistance, was not significantly different in the two groups of patients.
Dr. Mehra concluded, "All of the benefit seen with the HeartMate 3 was in reducing the rate of nondisabling strokes. Disabling stroke was a low-frequency event occurring in 5% to 7% of all patients in the trial. The overall stroke rate at 2 years is the lowest recorded to date in an LVAD trial."
Dr. Mehra noted that one limitation of the current study is that it was impossible for either patients or their doctors to be blinded to which device was implanted. The lack of blinding could have led to differences in the way doctors managed patients who had received the HeartMate 3 compared with the HeartMate II. However, the trial was rigorously designed to prevent such differences from occurring.
Another potential limitation is that the surgical techniques for implanting the two devices are different. All centers participating in the study had considerable experience with the HeartMate II and all received the same training on how to implant the HeartMate 3.
In addition to its use of magnetic levitation technology, Dr. Mehra highlighted the HeartMate 3 device's other design features that distinguish it from the HeartMate II. He explained, "First, the HeartMate 3 is small enough to be fully implanted in the chest, whereas the HeartMate II requires a 'pocket' to be created in the abdomen to accommodate the device. Second, the blood flow pathway is wider in the HeartMate 3, which may contribute to the reduction in pump thrombosis. Third, the HeartMate 3 is designed to speed up and slow down every 2 seconds, creating an artificial fixed pulse that may prevent blood from building up inside the device."