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

Abstract

The aim of this study was to match clinical outcomes of heart transplantation (HTx) against histopathologic and ultrastructural characteristics of marginal grafts preserved by cold storage (CS) or ex vivo normothermic perfusion. Since 2011, 100 patients had undergone HTx at our institution by using marginal donors (aged ≥55 years, expected ischemic time of >4 hours, left ventricular ejection fraction of ≤50%, interventricular septum thickness of ≥14 mm, drug abuse history, episodes of cardiac arrest, and presence of mild coronary artery disease). CS was utilized in 79 cases (Group 1, 79%), and ex vivo perfusion was utilized in 21 (Group 2, 21%). Pre-operative data, survival, and complications in the first 5 years after HTx were analyzed. Myocardial biopsies were collected at graft harvesting, just before implantation, and immediately after aortic declamping. Pre-operative demographics were similar in the 2 groups. Graft utilization rate with ex vivo perfusion was 81%. Ischemic, cardiopulmonary bypass, 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. Ex vivo perfusion allows for continuous evaluation of marginal donor hearts, favoring exclusion of unsuitable grafts, reduction of complications, and optimal survival of up to 5 years. Such results, supported by consistent histopathologic and ultrastructural findings, suggest better myocardial preservation.