<p>We report the case of a 15-year-old female with hypodiploid pre-B acute lymphoblastic leukemia status post allogeneic hematopoietic stem cell transplantation (HCT) from a matched unrelated male donor who presented on transplant day +75 with cardiac arrest due to ventricular fibrillation associated with fulminant myocarditis. Using conventional diagnostics, an exhaustive search for microbial pathogens in the heart biopsy as well as nasopharynx, blood, urine, and endotracheal aspirate was performed but did not uncover a candidate pathogen. The family consented to a research study for the use of unbiased next-generation genomic sequencing for pathogen identification in the myocardial biopsy. DNA sequencing was performed on 1.5 x 10<sup>8</sup> sequencing pairs and no microbial pathogens were identified. Interestingly, a significant component of Y-chromosomal human DNA was identified, suggesting infiltration of at least 10 donor leukocytes per host cell. This finding is grossly consistent with the lymphocyte:myocyte ratio in the biopsy according to visual inspection at 40x magnification. This case merits discussion due to (1) her survival after 17 days of veno-arterial extracorporeal life support (ECLS) and (2) the possibility of cardiotropic graft versus host disease (GVHD).</p>

ECLS Survival in Pediatric HCT Recipient with Presumed Cardiac GVHD