Lack of volume-outcome association in ECMO bridge to heart transplantation.

Abstract

Veno-arterial extracorporeal membrane oxygenation (VA-ECMO) is increasingly used as a bridge to cardiac transplantation. As the 2018United Network for Organ Sharing(UNOS) heart allocation policy change elevated waitlist status for patients receiving mechanical circulatory support (MCS), we aimed to determine if a center's annual heart transplant volume was associated with ECMO-support duration and posttransplant outcomes. Adults heart transplant candidates between January 1, 2011, and December 31, 2021, were isolated in the UNOS database. VA-ECMO use was identified at the time of listing for transplant. Average annual transplant volume was calculated by the center, with stratification as high (≥20 cardiac transplants, high volume center [HVC]) or low (<20 cardiac transplants, low volume center [LVC]) volume centers. Results are reported as mean(interquartile range) or n(%). In total, 543 patients at HVCs and 275 at LVCs were listed for transplant supported with VA-ECMO. Those listed at HVCs were more likely to be supported by intra-aortic balloon pump (103[19%] vs. 32[11.6%], p = .008) and inotropes (267[49.2%] vs. 106[38.5%], p = .004) at time of listing. Patients at HVCs received ECMO support for 6[4-9] days, compared to 8[4-15] days at low-volume centers (p = .030), and but were cannulated a similar time before listing (2[1-5] vs. 3[1-7] days, p = .517). There were no differences in rates of transplant (p = .2126), waitlist mortality (p = .8645), delisting due to clinical deterioration (p = .8419), or recovery (p = .1773) between groups. Among transplanted patients, there were no differences in support duration (6[4-8] vs. 6[4-10], p = .187), or time from registration to transplant (5[2-20] vs. 7[3-22] days, p = .560). Posttransplant survival did not vary (p = .293). LVCs can successfully bridge patients to transplant with VA-ECMO and achieve comparable outcomes to HVCs.