Regional thicknesses and thickening of compacted and trabeculated myocardial layers of the normal left ventricle studied by cardiovascular magnetic resonance

Abstract

Background: We used cardiovascular magnetic resonance (CMR) to study normal left ventricular (LV) trabeculation as a basis for differentiation from pathological noncompaction.

Methods and results: The apparent end-diastolic (ED) and end-systolic (ES) thicknesses and thickening of trabeculated and compacted myocardial layers were measured in 120 volunteers using a consistent selection of basal, mid, and apical CMR short-axis slices. All had a visible trabeculated layer in 1 or more segments. The compacted but not the trabeculated layer was thicker in men than in women (P<0.01 at ED and ES). When plotted against age, the trabeculated and compacted layer thicknesses demonstrated opposite changes: an increase of the compact layer after the fourth decade at both ED and ES (P<0.05) but a decrease of the trabeculated layer. There was age-related preservation of total wall thickness at ED but an increase at ES (P<0.05). The compacted layer thickened, whereas the trabeculated layer thinned with systole, but neither change differed between sexes. With age, the most trabeculated LV segments showed significantly greater systolic thinning of trabeculated layers and, conversely, greater thickening of the compact segments (P<0.05). Total wall thickening is neither sex nor age dependent. There were no sex differences in the trabeculated/compacted ratio at ES or ED, but the ES trabeculated/compacted ratio was smaller in older (50 to 79 years) versus younger (20 to 49 years) groups (P<0.05).

Conclusions: We demonstrated age- and sex-related morphometric differences in the apparent trabeculated and compacted layer thicknesses and systolic thinning of the visible trabeculated layer that contrasts with compacted myocardial wall thickening.

Figures

Figure 1

A, The systematic selection of basal, midcavity, and apical slices chosen for measurements of trabecular and compacted layer thickness is shown. The segmental incidence of apparent trabeculae seen at both ED and ES is indicated as percentages for each of the 16 segments. The dotted line indicates the ES location of the mitral valve. B, Examples of ED and ES frames showing the boundaries (dotted lines) of the trabeculated layer (red arrows) and compacted layer (blue arrows).

Figure 2

Compacted and trabecular layer thicknesses at ED per age group (anterior wall). Data are plotted as mean±SEM with the exception of the first data point representing the trabecular layer thickness in the 20 to 29 age group on segment 1, which is shown as median (first, third quartiles, 0, 4.6). *P<0.05 across age groups for the compacted layer. †P<0.05 across age groups for the trabecular layer.

Figure 3

Compacted and trabecular layer thicknesses at ES per age group (lateral wall). Data are plotted as mean±SEM. *P<0.05 across age groups for the compacted layer. †P<0.05 across age groups for the trabecular layer.

Figure 4

A, Total myocardial wall thickness (anterior wall) at ED and ES per age group. B, Total myocardial wall thickness (lateral wall) at ED and ES per age group. Data are plotted as mean±SEM. *P<0.05 across age groups for the total myocardial layer at ES. †P<0.05 across age groups for the total myocardial layer at ED.

Figure 5

Systolic trabecular layer thinning and compacted layer thickening shown as a pattern with age in the most trabeculated LV segments. Data are plotted as mean±SEM. *P<0.05 across age groups for the compacted layer. †P<0.05 across age groups for the trabecular layer.

Figure 6

A, Trabecular/compacted ratio at ED (red) and ES (blue) in each segment. B, Trabecular/compacted ratio at ES in younger versus older patients in all 16 segments. Data are plotted as mean±SEM. *P<0.05 in the young versus the old age group for each plotted segment.