Regional and global ventricular systolic function in isolated ventricular non-compaction Pathophysiological insights from magnetic resonance imaging

Background: Isolated ventricular non-compaction (IVNC) is frequently, but not invariably, associated with left ventricular (LV) systolic dysfunction. Factors impacting on regional and global LV function are unknown. The aim of the study was to apply magnetic resonance imaging (MRI) to evaluate the impact of extent and severity of ventricular non-compaction on LV systolic function in patients with IVNC. Methods: Sixteen adult patients with IVNC as defined by previously validated MRI criteria [ratio between end-diastolic thickness of non-compacted and compacted myocardium (NC/C ratio) >2.3 in >= 1 LV segment] were enrolled. Short-axis cine images were employed for analysis. Applying a 16-segment LV model, regional systolic performance was assessed qualitatively (wall motion score, WMS; 1 = normal, 2 = mild hypokinesia, 3 = moderate-to-severe hypokinesia, and 4 = a/dyskinesia) as well as quantitatively [fractional wall thickening, FWT (%)= 100x(end-diastolic wall thickness-end-systolic wall thickness) /end-diastolic wall thickness)]. Results: Mean LV ejection fraction was 43.8 +/- 15.4% (range, 17-68%). Regional disease severity, as expressed by the NC/C ratio, revealed a significant correlation with WMS (r = 0.26; p = 0.018) and FWT (r=-0.30; p = 0.006). The total number of non-compacted segments/patient (NoNC) as an index of disease extent was a significant independent correlate of LV ejection fraction by multivariate regression analysis (beta = -5.24; p = 0.038) and an excellent predictor of global LV dysfunction (ROC analysis, AUC = 0.98; p<0.0001). Conclusions: In patients with IVNC, disease severity correlates with the degree of LV dysfunction at a regional level. The extent of myocardial non-compaction is an independent predictor of global LV dysfunction. (C) 2011 Elsevier Ireland Ltd. All rights reserved.