Heart support systems help many patients with terminal heart failure. But they also bring with them a lot of complications. A new generation of devices now promises to minimize the risks and was subjected to a comparative test study.
Today, cardiologists have an arsenal of therapeutic options available to treat heart failure patients optimally. Nevertheless, there are some severe cases where conventional therapies fail or are not sufficient. These patients are increasingly being implanted with mechanical heart support systems, so-called left ventricular assist devices (LVADs). They are intended to bridge the time until heart transplantation, but can also be considered as permanent support. Today's LVADs with "axial flow" entail a lot of risks.
Pump thrombosis caused by non-physiological blood flow is among the most dangerous complications. They can lead to a stroke and, if they are detected in time, require a new operation to replace the LVAD. Now a new generation of LVADs has come onto the market that wants control such risks. The pump of the new devices is magnetically mounted and generates a centrifugal flow. On the one hand, this is intended to reduce the shear forces in the blood, thereby preventing hemolysis and the degradation of coagulation factors. On the other hand, centrifugal LVADs also simulate an artificial heartbeat so that the blood flows physiologically and clumps less frequently. A new study, recently published in the New England Journal of Medicine, has now compared the old and new generations of devices.
The study included 1,028 heart failure patients from 69 U.S. hospitals who needed an LVAD implant due to the severity of their condition. One-half of the participants received an axial LVAD (Heartmate II, by Abbot), the other half the novel centrifugal LVAD (Heartmate 3, also by Abbot). The primary endpoint of the study was survival after 2 years without stroke or LVAD exchange. The study was sponsored by medical device manufacturer Abbot.
Of the patients who received a centrifugal LVAD, 77% reached the primary endpoint after 2 years, compared to only 65% in the group of patients with axial LVAD technology. This corresponds to a significant difference of 12% (p < 0.001). The centrifugal LVADs also required far less replacement than axial LVADs (2.3% vs. 11.3%). The risk for an exchange surgery was 79% lower for centrifugal LVADs (p < 0.001). Even pump thromboses hardly occurred in the novel devices (1.4% vs. 13.9%, p < 0.001), which consequently reduced the number of strokes (9.9% vs. 19.4%, p < 0.001).
The scientists also investigated the frequency of bleeding during LVAD therapy. Again, treatment with centrifugal LVAD resulted in fewer bleeding events (43.7% vs. 55.0%, p < 0.001). In other complications of LVAD therapy (kidney and liver failure, right heart failure, infections, arrhythmias) there were no differences between the two devices.
The study shows that patients with centrifugal LVAD benefited from a significantly better outcome (fewer pump thromboses, strokes and replacement surgery) compared to patients who received a conventional axial LVAD. With the results of this study, a comprehensive introduction of the new technology has become more probable.
Source:
Mehra MR et al. A Fully Magnetically Levitated Left Ventricular Assist Device - Final Report. N Engl J Med 2019; 380:1618-1627 April 25, 2019. DOI: 10.1056/NEJMoa1900486