Prolonged Warm Ischemic Time is Safe for Cardiac Donation after Circulatory Death

PurposeProlonged warm ischemic time (WIT) has been considered a contraindication to cardiac transplant for donation after cardiac death (DCD). We anecdotally found excellent outcomes with DCD hearts with a prolonged WIT, prompting us to remove WIT restrictions. We hypothesized that a prolonged WIT is safe and can lead to excellent graft function.MethodsA retrospective analysis of DCD heart transplant recipients (02/2020-10/2022) was performed (N=104). Patients were stratified by WIT <25 (short WIT) or ≥25 (long WIT) minutes. WIT was defined as systolic BP<50 mmHg or SaO2 <70% to onset of reperfusion (normothermic regional perfusion (NRP)) or cross-clamp (machine perfusion (MP)). Outcomes included primary graft dysfunction (PGD), inotrope score, and 1-year survival with adjustment for reperfusion strategy (NRP or MP), pulmonary hypertension, preoperative temporary mechanical support, and intraoperative RBC transfusions.ResultsWIT data was available in 95 transplants (NRP: 71, MP: 24). Median WIT was 19 mins (IQR:17-24, Range:9-87). 20% had a long WIT (median WIT: 31 mins (IQR:28-67)). On unadjusted and adjusted analyses, WIT (as a continuous variable) was not associated with PGD (adjusted OR: 1.00 (0.98-1.01), P=0.56), 24hr inotrope score (B=-0.03 (-0.14-0.07), P=0.49), or 72hr inotrope score (B=0, (-0.1-0.1), P=0.9) (FIGURE). After stratifying into short vs long WIT, there was significantly more PGD in the long WIT group on unadjusted analysis (P=0.04). However, after adjustment, this was no longer significant (OR: 1.3 (0.75-2.31), P=0.35). Among hearts evaluated but turned down for transplant (N=9), WIT (22 (IQR:19-26) mins) was similar compared to hearts transplanted (P =0.39). 1-year survival was 92% with short WIT and 91% with long WIT (P=0.81).ConclusionProlonged WIT does not significantly impact early graft function in DCD heart transplantation. Given the opportunity to evaluate donor hearts in-situ or ex-vivo, elimination of WIT restrictions may allow for expansion of the donor pool. Prolonged warm ischemic time (WIT) has been considered a contraindication to cardiac transplant for donation after cardiac death (DCD). We anecdotally found excellent outcomes with DCD hearts with a prolonged WIT, prompting us to remove WIT restrictions. We hypothesized that a prolonged WIT is safe and can lead to excellent graft function. A retrospective analysis of DCD heart transplant recipients (02/2020-10/2022) was performed (N=104). Patients were stratified by WIT <25 (short WIT) or ≥25 (long WIT) minutes. WIT was defined as systolic BP<50 mmHg or SaO2 <70% to onset of reperfusion (normothermic regional perfusion (NRP)) or cross-clamp (machine perfusion (MP)). Outcomes included primary graft dysfunction (PGD), inotrope score, and 1-year survival with adjustment for reperfusion strategy (NRP or MP), pulmonary hypertension, preoperative temporary mechanical support, and intraoperative RBC transfusions. WIT data was available in 95 transplants (NRP: 71, MP: 24). Median WIT was 19 mins (IQR:17-24, Range:9-87). 20% had a long WIT (median WIT: 31 mins (IQR:28-67)). On unadjusted and adjusted analyses, WIT (as a continuous variable) was not associated with PGD (adjusted OR: 1.00 (0.98-1.01), P=0.56), 24hr inotrope score (B=-0.03 (-0.14-0.07), P=0.49), or 72hr inotrope score (B=0, (-0.1-0.1), P=0.9) (FIGURE). After stratifying into short vs long WIT, there was significantly more PGD in the long WIT group on unadjusted analysis (P=0.04). However, after adjustment, this was no longer significant (OR: 1.3 (0.75-2.31), P=0.35). Among hearts evaluated but turned down for transplant (N=9), WIT (22 (IQR:19-26) mins) was similar compared to hearts transplanted (P =0.39). 1-year survival was 92% with short WIT and 91% with long WIT (P=0.81). Prolonged WIT does not significantly impact early graft function in DCD heart transplantation. Given the opportunity to evaluate donor hearts in-situ or ex-vivo, elimination of WIT restrictions may allow for expansion of the donor pool.