Next-Gen LVAD Trial Highlights Evolving View of Device Use

The multicenter MOMENTUM 3 trial is about more than just demonstrating the efficacy and safety of a new left ventricular assist device (LVAD) that employs “magnetic levitation” technology. It may also help shift paradigms about how and when LVADs are used for patients with advanced heart failure.

Breaking down the bridge/destination distinction

Cleveland Clinic is among nearly 60 centers participating in MOMENTUM 3, which is randomizing more than 1,000 patients with advanced, refractory, left ventricular heart failure to either the Thoratec HeartMate 3™ LVAD — which is available in Europe but still investigational in the U.S. — or Thoratec’s currently marketed HeartMate II® LVAD. The new-generation device incorporates magnetic suspension technology designed to offer a more physiologic option for patients.

Instead of categorizing LVAD use either as a bridge to heart transplant or as destination therapy, the trial is using the primary end points of complication-free survival at six months and two years, regardless of indication.

Indeed, the classification of “bridge” for patients awaiting transplant versus “destination” for others doesn’t really make sense for a number of reasons, says Nader Moazami, MD, Director of Cleveland Clinic’s Cardiac Transplantation and Ventricular Assist Device Therapy Program. These include the fact that patients with LVADs on the transplant list may become ineligible for transplant over time and end up keeping the device in place long-term.

“About a third of patients don’t fit neatly into either category,” Dr. Moazami explains. “In this trial, all patients who are eligible for an LVAD can get one. Some are transplant candidates in whom device use may be short-term; if not, it becomes long-term.” He adds that although the traditional “bridge” and “destination” designations are thus highly arbitrary, for now the terminology is still necessary for record-keeping and reimbursement.

Will magnets mean better outcomes?

Unfortunately, Dr. Moazami notes, even with advances in technology many clinicians don’t refer for LVAD evaluation until patients are severely impaired. “Referral patterns haven’t changed,” he says. “Patients are referred later in the course of heart failure than they often should be.” He adds that this may be because of lingering concerns about complications despite significant improvements in LVAD outcomes over the past decade (see below).

Depending on the results of MOMENTUM 3 and ultimate FDA approval, the HeartMate 3’s advantages may help diminish that fear.

All LVADs work by the same basic mechanism, using an impeller that rotates and augments blood flow. The differences relate to how the impeller is suspended. Earlier LVADs used solid bearings, while the newer ones — including the HeartMate 3 — use magnetic suspension, which allows for wider gaps between the impeller and the pump’s housing.

“It’s a tremendous engineering feat to develop a pump of this size that’s fully magnetically suspended,” Dr. Moazami says. “The idea is that it causes less stress and trauma to blood elements.” It also will likely reduce the risk of clot formation and resultant stroke risk.

The magnetic “levitation” also allows for the pump’s action to be slowed or speeded up, thereby generating pulsation. “We think it’s more physiologic than those that can’t generate pulsation,” Dr. Moazami adds. “It’s a much more biocompatible pump.”

Results expected soon

MOMENTUM 3 is enrolling rapidly, and could be completed before the end of 2016. Dr. Moazami believes FDA approval could be possible based on results at the six-month end point, before the trial is fully completed.

“The technology is a tremendous advance,” he says. “Hopefully it will prove to be an even better device. We don’t have that proof yet, but theoretically there are many advantages.”

Longstanding LVAD leadership

Cleveland Clinic’s experience with LVADs dates to the early 1990s, when it was among the first centers to implant them. Today it implants approximately 60 LVADs every year (N = 61 in 2015).

Unfortunately, some of that LVAD volume is attributable to static heart transplant volumes due to recent scarcity of donor hearts. Waiting times for donor hearts have risen from under two months in 2008 to nearly 15 months in 2015. “Many patients end up receiving a mechanical support device just because appropriate organs aren’t available,” Dr. Moazami notes.

Even so, Cleveland Clinic transplanted 48 hearts in 2015 and 65 in 2014, and its graft survival rates in the most recent reporting period exceeded both expected and national rates at all time points — 1 month (96.3 percent), 1 year (94.4 percent) and 3 years (88.6 percent).

Its outcomes are similarly favorable for LVAD recipients, with two-year survival rates of approximately 80 percent for the period 2012-2015. In-hospital mortality among LVAD recipients in 2015 was 1.6 percent compared with a 9.9 percent expected rate from the University HealthSystem Consortium comparative database.

“We’re now better at taking care of patients with LVADs,” Dr. Moazami says. “In the past, these patients probably would have died within a year. We’ve been able to dramatically change the life expectancy for end-stage heart failure with these devices.”

Improvements from iteration and innovation

He attributes some of that success to development of tailored approaches to manage LVAD complications. “These devices are great, but they’re not perfect,” he says. “By creating clinical pathways and protocols, we’ve been able to handle complications well when they arise.”

Dr. Moazami also sees research involvement as a secret to LVAD success, citing his involvement in nearly two dozen trials of LVADs and other end-stage heart failure therapies in his time at Cleveland Clinic. “We’ve also developed many pump technologies,” he notes. “Much of our expertise comes from the research side, which gives us perspective to understand these technologies better rather than just using pumps that have been given to us.”

Image of HeartMate 3™ at the top of this post is reprinted with the permission of Thoratec Corporation.