Objective: To evaluate clinical characteristics, cardiac magnetic resonance imaging features, and outcomes of patients with left ventricle non-compaction.

Left Ventricle Non-Compaction Cardiomyopathy (LVNCC) is a type of myocardial disease characterized by prominent myocardial trabeculae and recesses resulting in two distinct layers of myocardium: compacted layer and the non-compacted layer. It arises due to the failure of left ventricle (LV) maturation and compaction during intra-uterine life (1). As per the position statement from the European Society of Cardiology, LVNCC has been labelled as 'unclassified' type of cardiomyopathy. Clinical course can be complicated by heart failure, thromboembolism, or arrhythmia.

Phenotypic presentation of LVNC can range from extremely thickened layer of non-compacted myocardium to mere presence of prominent trabeculae and recesses albeit a compacted myocardium. Transthoracic echocardiography is the first tool to diagnose LVNC. However, Cardiac Magnetic Resonance (CMR) imaging has emerged as a strong tool to differentiate between LVNCC from mere hyper-trabeculated LV myocardium when echocardiogram is inconclusive (Figure 1 and Video 1). Various criteria have evolved to diagnose LVNC by CMR. Peterson et al defined the end-diastole non-compacted to compacted myocardium ratio of >2.3 to have good sensitivity, specificity, and negative predictive value for differentiating pathological non-compaction from hyper-trabeculation.

With an increase in the use of diagnostic cardiovascular imaging modalities in South-Asian (SA) belt, LVNC is being increasingly diagnosed. The exact prevalence of LVNC in SA is not known and phenotypic CMR characteristics, clinical features, and outcomes of LVNC remain unknown for SA population. This brought us to the need of analysing CMR data of LVNC at our centre.

Inclusion Criteria:

• Patients > 18 years, referred for CMR for further evaluation of cardiomyopathy.

Exclusion Criteria:

• patients with intracardiac masses, pericardial diseases and congenital heart diseases were excluded from the study.

We retrospectively enrolled 294 patients referred for CMR from 2011 to 2020 for evaluation of cardiomyopathy. Of these, 51% were ischemic cardiomyopathy, 26% were dilated cardiomyopathy, 25% were hypertrophic cardiomyopathy, 13% were restrictive cardiomyopathy, and 6% were arrhythmogenic right ventricle dysplasia. For final enrolment, patients with intracardiac masses, pericardial diseases and congenital heart diseases were excluded from the study. Patients with evidence of LV non-compaction were further analysed for baseline characteristics, CMR parameters and outcomes. Characteristics of this group were compared with 47 patients who had dilated cardiomyopathy without evidence of LV non-compaction.