Ex Vivo Heart Perfusion for Higher Risk Cardiac Transplantations: A Retrospective Analysis from Two German Centers

Objectives: Ex vivo organ perfusion is an advanced preservation technique that allows graft assessment and extended ex situ intervals. We hypothesized that its properties for prolonged heart preservation might be especially beneficial for high risk recipients.

Methods: We reviewed the 1-year outcome of 126 end-stage heart failure patients that underwent cardiac transplantation in two German institutions between January 2015 and September 2018. Data were collected from prospective institutional databases. Patients were divided into two groups: group A (OCS) versus group B (conventional). Ex vivo organ perfusion was performed using Organ Care System (OCS Heart, Transmedics, United States). All recipients were potentially considered eligible, but an effort was made to apply the OCS Heart particularly in challenging cases with previous cardiac surgery.

Results: A total of 44 patients were transplanted using the OCS. Baseline characteristics in both groups: age (y) (A: 46.4 ± 16.2 vs. B: 32.1 ± 22.9; p < 0.001), male gender (%) (A: 75.0 vs. B: 67.1, p = 0.41), time on waiting list (d) (A: 639 ± 1,100 vs. B: 510 ± 789, p = 0.491), HU status (%) (A: 84.1 vs. B: 91.5, p = 0,241), previous VAD (%) (A: 72.7 vs. B: 62.2, p = 0.324). Operative results: ex situ time (min) (total preservation time Group A, ischemia for Group B) (A: 402 ± 67 vs. B: 225 ± 49, p < 0.001), operation time (min) (A: 488 ± 96.3 vs. B: 451 ± 133, p = 0.073), ventilation time (min) (A: 7.1 ± 15.4 vs. B: 17.6 ± 36.9, p = 0.123), ICU stay (d) (A: 14.2 ± 21 vs. B: 24.7 ± 36.9, p = 0.315), postoperative ECMO (%) (A: 18.2 vs. B: 28.4, p = 0.279), bleeding requiring redo surgery (%) (A: 20.5 vs. B: 20.7, p = 0.199), early graft rejection (%) (A: 9.3 vs. B: 20.0, p = 0.199), 30-day survival (%) (A: 99.6 vs. B: 91.2, p = 0.263), 1-year survival (%) (A: 88.6 vs. B: 78.2, p = 0.222).

Conclusion: OCS Heart allowed safe transplantation of surgically complex recipients with excellent 1-year outcomes, despite mean preservation times of almost 7 hours. Furthermore, we observed trends to decreased ventilation times, fewer ECMO treatments, and shorter ICU stays in the OCS group. In times of reduced organ availability and increasing recipient complexity, OCS heart is a strong instrument that enables otherwise infeasible allocations and contributes to increase surgical safety.