High ejection fraction of the left ventricular trabecular layer of the human heart.

Numerous diagnostic criteria for excessive trabeculation, or "noncompaction," score the extent of the trabecular layer. Whether the trabeculations themselves have a poor or good contractility is largely unknown. We retrospectively analyzed cardiac magnetic resonance (CMR) of patients with excessive trabeculation of the left ventricle (LV). The LV was labeled into four regions: compact wall, central cavity (CC), trabeculations, and intertrabecular recesses (IR). For each label we calculated the systolic fractional volume change (SFVC) in short‐axis images (n = 15) and systolic fractional area change (SFAC) in four‐chamber images (n = 30). We measured the ejection fraction (EF) of IR, CC, and total cavity. Three methods to calculate EF of the total cavity were compared: trabeculations included (per guidelines), IR excluded (Jacquier criterion), and trabeculations contoured and excluded (contour‐EF). The SFVC and SFAC of the compact wall were similar with SFVC and SFAC of trabeculations. In contrast, the IR were more diminished in systole by comparison with the CC, having lower SFVC (39% vs. 56%) and SFAC (37% vs. 72%). EF of the IR was also greater than EF of the CC (61% vs. 44%). Excluding IR from the total cavity or including trabeculations negatively impacts the EF (44% and 40%, respectively, vs. 51% for contour‐EF). The trabecular layer operates at a high EF. [ABSTRACT FROM AUTHOR]