Abstract 11480: Machine Learning Discovers a Prediction Model for Contractile Function of Circulatory Death Donor Hearts Based on Microvascular Flow Shifts During Ex-Situ Hypothermic Cardioplegic Machine Perfusion

Introduction: Hearts, procured from circulatory death donors (DCD) are predominantly resuscitated and maintained ex-vivo by machine perfusion (MP) with warm donor blood. Currently, DCD-heart function is evaluated by the course of lactate and by visual inspection. We have shown in an experimental research series that MP with the cardioplegic, crystalloid Custodiol-N solution is superior to blood perfusion to maintain DCD-hearts. However, no method has been developed yet to predict contractile function of DCD-hearts after continuous cardioplegic MP. Hypothesis: We hypothesize that the shift of microvascular flow during continuous MP with a cardioplegic preservation solution predicts contractile function of DCD-hearts. Methods: In a pig model, DCD-hearts were harvested and maintained by MP with hypothermic, oxygenated Custodiol-N solution for 4 h while myocardial microvascular flow (LDF) was measured by Laser-Doppler-Flow technology in the left ventricular wall. Subsequently, hearts were perfused with blood for 2 h and left ventricular contractility was measured with a balloon catheter after 30 and 120 min. Various novel parameters which represent the LDF-shift, were computed. Bivariate prediction models based on two combined LDF-shift parameters were identified based on machine learning algorithms. Results: Highest r 2 for ESP was 0.77 (p=0.027), for dp/dt max was 0.73 (p= 0.037) and for dp/dt min was 0.75 (p=0.032) after 30 min of reperfusion. After 120 min of reperfusion, highest r 2 for ESP was 0.81 (p=0.016), for dp/dt max was 0.90 (p=0.004) and for dp/dt min 0.58 (p=0.115). Identical prediction models were identified for dp/dt max and for dp/dt min at both time points of reperfusion. Lactate remained constant during MP and therefore was unsuitable for prediction. Conclusions: Contractile function of DCD-hearts after continuous MP with a cardioplegic preservation solution can be predicted by the shift of LDF during MP.