MOMENTUM 3: Fewer Reoperations With HeartMate 3 vs HeartMate 2 at 6 Months

Marlene Busko

November 17, 2016

NEW ORLEANS, LA — Patients with advanced heart failure who received the investigational (in the US) HeartMate 3 left ventricular assist system (LVAS) and those who were implanted with the long-available HeartMate 2 (both from St Jude Medical) had a similar risk of having a disabling stroke within 6 months, but the newer device was less likely to develop thrombosis or otherwise malfunction and require replacement[1].

Dr Mandeep Mehra

Dr Mandeep R Mehra (Brigham and Women's Hospital and Harvard Medical School, Boston, MA) presented these interim 6-month findings in 194 patients from the ongoing Multicenter Study of MagLev Technology in Patients Undergoing Mechanical Circulatory Support Therapy with HeartMate 3 (MOMENTUM 3) at a press briefing prior to a late-breaking clinical-trials session here at the American Heart Association (AHA) Scientific Sessions; the study was published online in the New England Journal of Medicine.

The most important finding was that there were fewer reoperations with the HeartMate 3 as opposed to the HeartMate 2, said Mehra. The newer LVAS eliminated the adverse event it was designed to prevent— pump thrombosis—the "principal driver" of reoperations with this device, he added. The other adverse events as well as improvements in quality of life were similar in both patient groups.

Reducing thrombosis to zero is "particularly helpful" for patients who are not suitable candidates for a heart transplant and receive the LVAS for destination therapy as opposed to a bridge to transplant, assigned discussant Dr Mark S Slaughter (University of Louisville, Kentucky) noted.

However, long-term data from MOMENTUM 3, which will randomize 1028 patients and follow them for 2 years, should shed more light on this. "Clearly long-term data is needed to determine whether there will be a significant impact on long-term survival, adverse events, and quality of life that will make LVAD support a viable or even competitive alternative to heart transplantation," he said.

In the meantime, this trial showed that the HeartMate 3 provides an important incremental benefit over HeartMate 2, he told heartwire from Medscape.

And echoing a comment made by session moderator Dr Clyde Yancy (Northwestern University, Chicago, IL), he said that it provides support for use of LVADs, showing that "in appropriately selected patients" with advanced heart failure, an LVAD is "the right thing to do."

"Time will tell" whether this study changes referrals of patients for LVADs from clinicians who were worried about adverse events, said Yancy and Slaughter.

Device Designed to Address Pump Thrombosis

Clinicians have been concerned about reports of pump thrombosis with the HeartMate 2 axial continuous-flow pump (which is approved for both bridge-to-transplant and destination therapy) and the HVAD (HeartWare) centrifugal continuous-flow pump (which is approved for bridge to transplant), Mehra and colleagues write.

HeartMate 3, which received CE Mark in Europe a year ago[2] but has not yet been approved by the US Food and Drug Administration (FDA), was specifically engineered to avert pump thrombosis.

It is a magnetically levitated centrifugal continuous-flow pump that has wide blood-flow passages to reduce shear stress, is frictionless, and is programmed to create an intrinsic artificial pulse, Mehra explained.

MOMENTUM 3 is designed to compare clinical outcomes with HeartMate 3 vs Heartmate 2 in "all comers"—patients who receive a device as a bridge to transplant or as destination therapy, he stressed.

This first interim analysis at 6 months aimed to see whether the HeartMate 3 was noninferior to the HeartMate 2 in 294 patients. Next, the researchers will see whether the newer device is noninferior to the older device in 366 patients at 2 years. The full study is powered to determine whether the HeartMate 3 is superior to the HeartMate 2 in 1028 patients, at 2 years.

The current analysis looked at outcomes in 152 patients who were randomized to receive HeartMate 3 and 142 patients who were randomized to receive Heartmate 2, at 47 US sites.

Similar percentages of patients in each study arm received the device as a bridge to transplant (27%), a bridge to candidacy for a transplant (18%), or, most commonly, as destination therapy (55%).

The primary end point was a composite of 6-month survival without a disabling stroke (modified Rankin score >3) and without another operation to replace or remove the device.

This end point was met in 86% of patients in the HeartMate 3 group vs 77% of patients in the HeartMate 2 group (hazard ratio 0.55, 95% CI 0.32–0.95; P=0.04).

Thus, "even at 6 months the trial met the superiority end point," said Dr Mehra.

Both groups had similar rates of disabling stroke (4%).

However, only one patient (1%) in the HeartMate 3 group vs 11 patients (8%) in the HeartMate 2 group had a reoperation for a malfunctioning pump (HR 0.08, 95% CI 0.01–0.60; P=0.002).

None of the patients in the HeartMate 3 group vs 14 patients (10%) in the HeartMate 2 group had suspected or confirmed pump thrombosis.

Rates of other major adverse events were similar in each group, including any stroke (roughly 9%); neurologic events other than stroke, including transient ischemic attack (TIA) (6%); any bleeding (35%), and gastrointestinal bleeding (15%).

One in 10 patients in each group died within 6 months of implantation of the device.

Functional status, assessed with the NYHA classification and the 6-minute-walk test, improved equally in both groups.

Thus, "among patients with advanced heart failure, implantation of a fully magnetically levitated centrifugal-flow pump was associated with better outcomes at 6 months than was implantation of an axial-flow pump, primarily because of the lower rate of reoperation for pump malfunction," the researchers summarize.

The study was supported by St Jude Medical. Mehra reports nonfinancial support from St Jude Medical during the conduct of the study and personal fees from Stealth Biotherapeutics, Medtronic, Johnson & Johnson (Janssen), and Teva Pharmaceuticals. Disclosures for the authors are listed on the journal website. Slaughter was an investigator in this trial and did preclinical work for the development of the HeartMate 3.

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