Preservation by cold storage vs ex vivo normothermic perfusion of marginal donor hearts: clinical, histopathological and ultrastructural features.

ABSTRACT Objective To match clinical outcomes of heart transplantation against histopathological and ultrastructural characteristics of marginal grafts preserved by cold storage or ex vivo normothermic perfusion. Methods Since 2011, 100 patients had undergone heart transplantation at our institution by using marginal donors (age ≥55 years; expected ischemic time >4h; left ventricular ejection fraction ≤50%; interventricular septum thickness ≥14mm; drug abuse history; episodes of cardiac arrest and presence of mild coronary artery disease). Cold storage was utilized in 79 cases (Group 1, 79%) and ex-vivo perfusion in 21 (Group 2, 21%). Pre-operative data, survival and complications in the first 5 years post HTx were analysed. Myocardial biopsies were collected at graft harvesting (T0), just prior to implantation (T1) and immediately after aortic declamping (T2). Results Preoperative demographics were similar in the two groups. Graft utilization rate with ex-vivo perfusion was 81%. Ischemic, cardio-pulmonary by-pass and surgical times were shorter in Group 2 patients, who showed a lower incidence of overall complications (33% vs 13%, p=0.04) and better 5-year survival (log-rank p=0.04). Moreover, restoration of hypertrophy-related sarcomere changes and mitigation of reperfusion-dependent myocardium injuries were more frequently observed in Group 2 hearts. Conclusions Ex-vivo perfusion allows continuous evaluation of marginal donor hearts favouring exclusion of unsuitable grafts, reduction of complications and optimal survival up to 5 years. Such results, supported by consistent histopathological and ultrastructural findings, suggest better myocardial preservation.