Correlation of trabeculae and papillary muscles with clinical and cardiac characteristics and impact on CMR measures of LV anatomy and function

Abstract

Objectives: The goal of this study was to assess the relationship of left ventricular (LV) trabeculae and papillary muscles (TPM) with clinical characteristics in a community-based, free-living adult cohort and to determine the effect of TPM on quantitative measures of LV volume, mass, and ejection fraction (EF).

Background: Hypertrabeculation has been associated with adverse cardiovascular events, but the distribution and clinical correlates of the volume and mass of the TPM in a normal left ventricle have not been well characterized.

Methods: Short-axis cine cardiac magnetic resonance images, obtained using a steady-state free precession sequence from 1,494 members of the Framingham Heart Study Offspring cohort, were analyzed with software that automatically segments TPM. Absolute TPM volume, TPM as a fraction of end-diastolic volume (EDV) (TPM/EDV), and TPM mass as a fraction of LV mass were determined in all offspring and in a referent group of offspring free of clinical cardiovascular disease and hypertension.

Results: In the referent group (mean age 61 ± 9 years; 262 men and 423 women), mean TPM was 23 ± 3% of LV EDV in both sexes (p = 0.9). TPM/EDV decreased with age (p < 0.02) but was not associated with body mass index. TPM mass as a fraction of LV mass was inversely correlated with age (p < 0.0001), body mass index (p < 0.018), and systolic blood pressure (p < 0.0001). Among all 1,494 participants (699 men), LV volumes decreased 23%, LV mass increased 28%, and EF increased by 7.5 EF units (p < 0.0001) when TPM were considered myocardial mass rather than part of the LV blood pool.

Conclusions: Global cardiac magnetic resonance LV parameters were significantly affected by whether TPM was considered as part of the LV blood pool or as part of LV mass. Our cross-sectional data from a healthy referent group of adults free of clinical cardiovascular disease demonstrated that TPM/EDV decreases with increasing age in both sexes but is not related to hypertension or obesity.

Figure 1. Examples of TPM quantitation

a) end-diastolic mid-LV slice from a relatively lightly trabeculated participant. b) the same slice after endocardial and epicardial border detection and segmentation of TPM; TPM are shown in black and the residual bloodpool (slice EDV_ADJ) is shown in white. For this slice EDV_INIT = 24.6 ml and LVM_INIT = 12.5 g, while slice EDV_ADJ =19.9 ml and LVM_ADJ = 17.5g. Panels (c) and (d) are from a more heavily trabeculated participant with slice EDV_INIT = 21.5 ml and LVM_INIT = 17.4 g, following TPM segmentation slice EDV_ADJ = 12.1 ml and LVM_ADJ = 27.3 g.