Impact of Prolonged Ischemic Time on Pediatric Heart Transplantation Outcomes: Improved Outcomes in the Most Recent Era

Background Impacts of ischemic time (IT) on pediatric heart transplant outcomes are multifactorial. We aimed to analyze the effect of prolonged IT on graft loss after pediatric heart transplantation. We hypothesized that graft survival with prolonged IT has improved across eras. Methods Patients <18 years old in the Pediatric Heart Transplant Society database (1993-2019) were included (N=6765) and stratified by diagnosis and era (1993-2004, 2005-2009, and 2010-2019). Severe graft failure (SGF) was defined as death, re-transplant, or need for mechanical circulatory support in the first 7 days post-transplant. Descriptive statistical methods were used to compare differences between patient characteristics and IT. Kaplan-Meier survival analysis compared freedom from graft loss, rejection, and infection. Multivariable analysis was performed for graft loss and SGF (hazard and logistic regression modeling, respectively). Results Diagnoses were cardiomyopathy (N=3246) and congenital heart disease (CHD; N=3305). CHD were younger, more likely to have an IT >4.5 hours, and more likely to require extracorporeal membrane oxygenation or mechanical ventilation at transplant (all P<0.001). Median IT was 3.6 hours [IQR 2.98 to 4.31; range 0-10.5]. IT was associated with early graft loss (HR 1.012, 95% CI 1.005-1.019), but not when analyzed only in the most recent era. IT was associated with SGF (OR 1.016 95%CI 1.003 - 1.030). Conclusions Donor IT was independently associated with increased risk of graft loss, albeit with a small effect relative to other risk factors. Graft survival with prolonged IT has improved in the most recent era but the risk of SGF persists.