Risk Factors and Outcomes of Sudden Cardiac Arrest in Pediatric Heart Transplant Recipients

Background: Sudden cardiac arrest (SCA) is a prevailing cause of mortality after pediatric heart transplant (HT) but remains understudied. We analyzed the incidence, outcomes, and risk factors for SCA at our center. Methods: Retrospective review of all pediatric HT patients at our center from 1/1/2009-9/1/2021. SCA was defined as an abrupt loss of cardiac function requiring cardiopulmonary resuscitation and/or mechanical circulatory support (MCS). Events that occurred in the setting of limited resuscitative wishes, or while on MCS were excluded. Patient characteristics and risk factors were analyzed. Results: Fourteen of 254 (6%) experienced SCA at a median of 3 (1, 4) years post-HT. Seven (50%) events occurred out-of-hospital. Eleven (79%) died from their initial event, 2 (18%) after failure to separate from extracorporeal membrane (ECMO). In univariate analysis, black race, younger donor age, prior acute cellular rejection (ACR) episode, pacemaker and/or ICD in place, and pre-mortem diagnosis of allograft vasculopathy were associated with SCA (P=0.003-0.02). In multivariable analysis, history of ACR, younger donor age, and black race retained significance. [OR=6.3, 95% CI: 1.6-25.4, P=0.01], [OR=0.9, 95% CI: 0.8-1, P=0.04], and [OR=7.3, 95% CI: 1.1-49.9, P=0.04], respectively. SCA occurred in 3 patients with a functioning ICD or pacemaker, which failed to restore a perfusing rhythm. Conclusions: SCA occurs relatively early after pediatric HT and is usually fatal. Half of events happen at home. Those who received younger donors, have a history of ACR, or are of black race are at increased risk. ICDs/pacemakers may offer limited protection.