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

ABSTRACT

BACKGROUND: Veno-arterial extracorporeal membrane oxygenation (VA-ECMO) is increasingly used as a bridge to cardiac transplantation. As the 2018 United 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. METHODS: 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 (%). RESULTS: 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). CONCLUSIONS: LVCs can successfully bridge patients to transplant with VA-ECMO and achieve comparable outcomes to HVCs.