Atrial Electrophysiological Properties of Normothermic Ex Situ Perfused Hearts Donated after Circulatory Death

Background Donation after circulatory death (DCD) hearts undergo warm and cold ischemia before transplantation. Atrial ischemia is an important contributor to development of electrophysiological abnormalities and post-transplantation atrial arrhythmias. The purpose of this study was to characterize atrial electrophysiological properties of DCD hearts during normothermic ex-situ heart perfusion (ESHP), and to report post-transplantation incidence of atrial tachyarrhythmias, sinus node dysfunction (SND) and atrioventricular block (AVB). Methods High-resolution epicardial mapping was performed in 23 human DCD hearts during ESHP and compared to a control group consisting of 15 patients undergoing intra-operative epicardial mapping during coronary artery bypass surgery. Unipolar potential voltages and potential types (single, short double, long double and complex potentials), conduction velocity (CV), continuous conduction delay and block (cCDCB) lines were quantified in the right atrium (RA), including the sinoatrial node (SAN) exit site, Bachmann's bundle (BB) and the left atrium (LA). The occurrence of post-transplantation atrial tachyarrhythmias, SND and AVB were evaluated. Results The atria of DCD hearts were characterized by lower median potential voltages and a higher proportion of low-voltage areas, fractionation and areas of slow and heterogeneous conduction. Atrial tachyarrhythmias (57%), SND (9%) and AVB (13%) were prevalent in DCD hearts after transplantation. Patients with post-transplantation AVB had significantly longer functional warm ischemic times (FWIT) (24 vs. 18 minutes, p=0.002) and first cold ischemic times (CIT-1) (43 [35–43] vs. 34 [31–35] minutes, p=0.033), whereas patients with AF had significantly longer second cold ischemic times (CIT-2) (103 vs. 80 minutes, p=0.038). Conclusion During ESHP, atrial electrophysiological properties of the DCD hearts are characterized by abnormal electrical signal morphologies and conduction abnormalities. Post-transplantation arrhythmias are prevalent and are associated with ischemia duration during the transplantation procedure. Translational perspective DCD hearts show atrial electrical abnormalities during normothermic ex-situ heart perfusion, reflecting ischemic injury that may predispose recipients to early post-transplant arrhythmias. Electrical abnormalities at the sinoatrial node activation site and in atrioventricular conduction are detectable before transplantation and may be associated with post-transplant sinus node dysfunction and atrioventricular block. After transplantation, atrial fibrillation and atrial flutter occur frequently. These findings support intensified perioperative rhythm surveillance, consideration of early pacing strategies, and efforts to minimize ischemic time to improve rhythm outcomes after DCD heart transplantation.