Abstract
BackgroundLeft ventricular (LV) non-compaction (LVNC) is defined by extreme LV trabeculation, but is measured variably. Here we examined the relationship between quantitative measurement in LV trabeculation and myocardial deformation in health and disease and determined the clinical utility of semi-automated assessment of LV trabeculations.MethodsCardiovascular magnetic resonance (CMR) was performed in 180 healthy Singaporean Chinese (age 20–69 years; males, n = 91), using balanced steady state free precession cine imaging at 3T. The degree of LV trabeculation was assessed by fractal dimension (FD) as a robust measure of trabeculation complexity using a semi-automated technique. FD measures were determined in healthy men and women to derive normal reference ranges. Myocardial deformation was evaluated using feature tracking. We tested the utility of this algorithm and the normal ranges in 10 individuals with confirmed LVNC (non-compacted/compacted; NC/C ratio > 2.3 and ≥1 risk factor for LVNC) and 13 individuals with suspected disease (NC/C ratio > 2.3).ResultsFractal analysis is a reproducible means of assessing LV trabeculation extent (intra-class correlation coefficient: intra-observer, 0.924, 95% CI [0.761–0.973]; inter-observer, 0.925, 95% CI [0.821–0.970]). The overall extent of LV trabeculation (global FD: 1.205 ± 0.031) was independently associated with increased indexed LV end-diastolic volume and mass (sβ = 0.35; p < 0.001 and sβ = 0.13; p < 0.01, respectively) after adjusting for age, sex and body mass index. Increased LV trabeculation was independently associated with reduced global circumferential strain (sβ = 0.17, p = 0.013) and global diastolic circumferential and radial strain rates (sβ = 0.25, p < 0.001 and sβ = −0.15, p = 0.049, respectively). Abnormally high FD was observed in all patients with a confirmed diagnosis of LVNC. Five out of 13 individuals with suspected LVNC had normal FD, despite NC/C > 2.3.ConclusionThis study defines the normal range of LV trabeculation in healthy Chinese that can be used to make or refute a diagnosis of LVNC using the fractal analysis tool, which we make freely available. We also show that increased myocardial trabeculation is associated with higher LV volumes, mass and reduced myocardial strain.
Highlights
Left ventricular (LV) non-compaction (LVNC) is defined by extreme LV trabeculation, but is measured variably
Left ventricular (LV) non-compaction (LVNC) is a clinically heterogeneous myocardial disorder characterized by increased LV trabeculation and deep inter-trabecular recesses that are in continuity with the LV cavity, but not the epicardium
Reduction in myocardial deformation has been shown in Left ventricular non-compaction (LVNC) patients [36,37,38,39], our study demonstrated progressive impairment in regional circumferential strain with LV trabeculation extent even in healthy individuals
Summary
Left ventricular (LV) non-compaction (LVNC) is defined by extreme LV trabeculation, but is measured variably. Variable degrees of LV trabeculation have been observed in other cardiac conditions, including dilated and hypertrophic cardiomyopathies [7,8,9], congenital heart disease [10], and in healthy individuals such as in pregnant women or athletes [6, 11, 12], suggesting that it may be a remodeling epiphenomenon or anatomical phenotype [13] This has led to much controversy over the diagnostic criteria for LVNC, while the physiological consequences of variable degrees of LV trabeculation in healthy individuals are unknown [14, 15]. It is important to study the phenotypic variability of LV trabeculation in the normal population and develop normal reference ranges for these measures using automated and robust approaches
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