Hypertrabeculated Left Ventricular Myocardium in Relationship to Myocardial Function and Fibrosis: The Multi-Ethnic Study of Atherosclerosis

Abstract

Purpose To determine if excess greater left ventricle (LV) trabeculation is associated with decreased average regional myocardial function, diffuse fibrosis, or both. Materials and Methods This was a HIPAA-compliant institutional board approved multicenter study, and all participants provided written informed consent. Participants in the Multi-Ethnic Study of Atherosclerosis (MESA) underwent a comprehensive cardiac magnetic resonance (MR) examination. LV trabeculation was measured with the maximal apical fractal dimension (FD), which is a marker of endocardial complexity. Demographic covariates, cardiovascular risk factors, and cardiac MR measurements were compared across quartiles of FD. Associations between FD and peak regional systolic circumferential strain (Ecc) and T1 time, a surrogate for diffuse myocardial fibrosis, were assessed with multivariable linear regression models. Results A total of 1123 subjects (593 [52.8%] female; mean age, 67.1 years ± 8.7 [standard deviation]) underwent FD and Ecc measurement, and 992 (521 [52.5%] female; mean age, 67.1 years ± 8.7) underwent FD and T1 measurement. Mean FD was 1.2 ± 0.07 in both groups, and mean Ecc was -18.3 ± 2.27 in the subjects who underwent FD and Ecc measurement. Global volumes and ejection fraction showed no differences between FD quartiles. However, with increasing FD quartile, Ecc was greater (indicating worse average regional function) (P < .001). After adjustment, greater trabeculation was associated with 21% worse myocardial strain (relative to the mean) per unit change in FD (regression coefficient = 4.0%; P < .001). There was no association between the degree of trabeculation and diffuse fibrosis measured with T1 mapping. Conclusion Average regional LV function was worse in individuals with greater LV trabeculation, supporting the concept of hypertrabeculation being an epiphenomenon of disease. ^© RSNA, 2017.

Figure 1:

Flowchart shows participant enrollment. Incl. = including, w/o = without.

Figure 2:

Analysis of MR images of FD. FD was measured via fractal analysis of short-axis cine steady-state free precession images in four exemplar subjects from the MESA cohort: one subject with low FD (top) and three subjects with high FD (rows 2, 3, and 4). Colored lines show contouring of endocardial borders. FD indicates how extensively the contour fills two-dimensional space. The image on the left shows planning of the short-axis cine stack. Numbers on top of each short-axis image indicate the FD of the respective section. Colored panels on the right give characteristics of the four subjects. AfrcAm = African American, BMI = body mass index, Hisp = Hispanic, HT med = hypertension medication, N = no, SBP = systolic blood pressure, Y = yes.

Figure 3:

Graph shows circumferential strain by quartiles of FD. Quartile 1, FD = 1.01–1.15; quartile 2, FD = 1.15–1.12; quartile 3, FD = 1.12–1.24; and quartile 4, FD = 1.24–1.4. Error bars indicate the 95% confidence interval.