Susan W. Denfield

Background Although ventricular failure is a late finding in adults with AC, we hypothesize that this is a presenting symptom in pediatric heart failure patients who undergo HT and that their ventricular arrhythmia burden could differentiate AC from other cardiomyopathies. Methods We performed a single‐center retrospective cohort study reviewing 457 consecutive pediatric (≤18 years) HT recipients at our institution. Explanted hearts were examined to establish the primary diagnosis, based on pathologic findings. Demographic and clinical variables were compared between AC versus non‐HCM cardiomyopathy cases. Results Forty‐five percent ( n = 205/457) had non‐HCM cardiomyopathies as the underlying primary diagnosis. Ten cases (10/205 = 4.9%) were diagnosed with AC. All 10 had biventricular disease. In 8/10 patients (80%), AC diagnosis was unrecognized pre‐HT. Compared with non‐AC cardiomyopathies, the AC group was older at diagnosis (9.3 years vs. 4.3 years, p = .012) and transplant (11.1 years vs. 6.5 years, p = .010), had more ventricular arrhythmias (80.0% vs 32.8%, p = .003), and required more anti‐arrhythmic use (80.0% vs 32.3%, p = .001). Genetic testing yielded causative pathogenic variants in all tested individuals ( n = 5/5, 100%). Conclusion AC is often an unrecognized cardiomyopathy pretransplant in children who undergo HT. Pediatric non‐HCM phenotypes with heart failure who have a significant ventricular arrhythmia burden should be investigated for AC.