Background .– Isolated ventricular non-compaction is a congenital cardiomyopathy, based on an arrest of normal embryonic myocardium development and characterized by the presence of a two-layered myocardial structure, with a compacted epicardial band and a non-compacted endocardial layer of prominent trabeculations. It is sometimes complicated by ventricular dysfunction and heart failure, arrhythmias or thrombo-embolic events.

The aim of our study was to look for a potential relationship between magnetic resonance imagery’s non-compaction extension criteria and these clinical events.

Methods .– Between 2004 and 2013, we conducted a retrospective study reviewing magnetic resonance imagery with diagnosis of non-compaction. One hundred and twenty-five patients presented magnetic resonance imagery’s non-compaction criteria but 26 of them had another associated cardiomyopathy. Finally, 99 patients fulfilled the diagnosis of isolated ventricular non-compaction and were included in the study. Left ventricular ejection fraction, left ventricular volumes, global left ventricular mass, compacted and non-compacted left ventricular mass, number of non-compacted segments and non-compaction score were measured. Non-compaction score was the sum of the ratios of the thickness of non-compacted to compacted myocardial layers superior to 2.3, measured in the diastolic phase.

Results .– There was no statistical relationship between left ventricular ejection fraction alteration and non-compaction score ( P = 0.57) or number of non-compacted segments ( P = 0.97), between stroke incidence and non-compaction score ( P = 0.22) or number of non-compacted segments ( P = 0.96) and between ventricular arrhythmias and non-compaction score ( P = 0.59) and number of non-compacted segments ( P = 0.59). Conversely, we found a significant inverse relationship between left ventricular ejection fraction and compacted mass ( P < 0.0001) and between stroke and compacted mass ( P = 0.007).

Conclusion .– Our study did not show any association between magnetic resonance imagery criteria of non-compaction extension and clinical events. Conversely, we found a relationship between compacted mass and left ventricular ejection fraction dysfunction and the incidence of strokes, but not of ventricular arrhythmias. These findings suggest that isolated left ventricular non-compaction does not involve only the non-compacted part of the myocardium, but also its compacted part.