At six months, patients with advanced heart failure who were implanted with the HeartMate 3 left ventricular assist system were less likely to have hemocompatibility- related clinical adverse events (HRAEs) compared with those who received the HeartMate II device, according to a randomized trial.

The researchers defined HRAEs as clinical adverse events attributable to left ventricular assist system-related bleeding or thrombosis abnormalities.

Lead researcher Nir Uriel, MD, of the University of Chicago, and colleagues published their results online in Circulation on April 6. The findings were also presented at the International Society for Heart and Lung Transplantation annual meeting in San Diego.

For this secondary analysis, the researchers evaluated the MOMENTUM 3 trial, a prospective, multicenter, randomized, non-blinded, pivotal study comparing the HeartMate 3 and HeartMate II in patients with advanced-stage heart failure

Abbott, which manufactures the HeartMate 3 and HeartMate II, funded the study. The FDA has approved the HeartMate II, but it has not approved the HeartMate 3, which is a continuous-flow centrifugal pump.

The researchers considered the following as HRAEs: nonsurgical bleeding more than 30 days after implant; stroke or other neurological events at anytime; and suspected or confirmed pump thrombosis or arterial thromboembolism with or without organ involvement at any time.

At six months, 69 percent of patients in the HeartMate 3 group and 55 percent of patients in the HeartMate II group had survived and were free of any HRAE. For patients who were 65 years old or younger, the rates were 76 percent and 58 percent, respectively. For patients who were older than 65, the rates were 61 percent and 47 percent, respectively.

Patients in the HeartMate 3 group mostly had bleeding events, while bleeding and thromboembolic events were equally distributed in the HeartMate II group. The HeartMate 3 patients also had a 6.3 percent reduction in days spent in the hospital because of readmission.

A univariable analysis found that patients who experienced any HRAE or death were more often implanted with the HeartMate II, were older, received the device as destination therapy, were more likely to have an international normalized ratio (INR) less than 1.5 and were not on aspirin 30 days after the implant.

Meanwhile, a multivariable analysis found that the HeartMate II, older age, absence of aspirin at 30 days and an INR less than 1.5 at 30 days were independently associated with developing an HRAE or dying at six months after the implant.

The researchers also developed a hemocompatibility score (HCS) that weighed each event by its escalating clinical relevance. They found that the HCS was 0.67 points per patient in the HeartMate 3 group and 0.99 points per patient in the HeartMate II group, which did not represent a statistically significant difference.

“Patients implanted with the HeartMate 3 gained a significant increase in freedom from adverse events, driven predominantly by a reduction in non-disabling strokes and complete absence of pump thrombosis, compared with the HeartMate II," senior author Mandeep R. Mehra, MD, medical director of the Brigham and Women's Hospital Heart and Vascular Center in Boston, said in a news release “No patients on the HeartMate 3 had pump-related clotting, requiring a pump reoperation. There was also no difference in disabling strokes, a typically devastating complication."

The analysis had a few limitations, according to the researchers, including its short follow-up period. They also mentioned that the hemocompatibility endpoint could have missed bleeding events that occurred less than 30 days after implant. In addition, they did not evaluate the role of infection and its consequent inflammatory state in driving a change in the hemocompatibility milieu.

“These data provide further evidence that the [HeartMate3] has a more favorable physiological circulatory interface than does the [HeartMate II],” the researchers wrote.