Electrophysiologic and electroanatomic characterization of ventricular arrhythmias in non‐compaction cardiomyopathy: A systematic review

Abstract Background Non‐compaction cardiomyopathy (NCCM) is a form of structural heart disease prone to ventricular arrhythmias (VAs) and sudden cardiac death. Non‐compacted myocardium may harbor VA substrate, though some reports suggest otherwise. Objective This study aimed to characterize the electrophysiologic (EP) features of VA in NCCM. Methods We performed a systematic review of case reports, case series, and observational studies. Results One hundred and thirty‐five cases of NCCM from studies between 2000 and 2020 were included. Mean age was 34 ± 20 years, mean left ventricular (LV) ejection fraction was 42 ± 15% with two cases having late gadolinium enhancement on magnetic resonance imaging. The LV apex was the most common non‐compacted segment (86%); 10% involved the right ventricle (RV). Antiarrhythmic failure was documented in 16 cases, of which 50% failed more than one agent. Only 23% of monomorphic VAs localized to regions of non‐compaction on electrocardiogram. Most frequently, VAs localized to the RV outflow tract ( n = 21), posterior fascicle ( n = 19), and anterolateral LV apex ( n = 9). All cases with apical exits arose from the non‐compacted myocardium. On EPS, 83% of sustained VTs were due to re‐entry, 17% due to focal mechanism. Catheter ablation was performed in 39 cases, with 7 requiring more than 1 procedure. Acute VA non‐inducibility was achieved in 82% and VA‐free survival was reported in 85% over a mean follow‐up of 24 months. Conclusion The majority of VAs in NCCM arise remotely from non‐compacted myocardium, and non‐re‐entrant mechanism seen in ~1/5th of sustained VTs. Catheter ablation outcomes appear favorable. Further study is needed to understand the pathophysiology of VA in NCCM.