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

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.