Fractal analysis of myocardial trabeculations in 2547 study participants: Multi-ethnic study of atherosclerosis¹

Purpose: To quantitatively determine the population variation and relationship of left ventricular (LV) trabeculation to LV function, structure, and clinical variables. Materials and Methods: This HIPAA-compliant multicenter study was approved by institutional review boards of participating centers. All participants provided written informed consent. Participants from the Multi-Ethnic Study of Atherosclerosis with cardiac magnetic resonance (MR) data were evaluated to quantify LV trabeculation as a fractal dimension (FD). Entire cohort participants free of cardiac disease, hypertrophy, hypertension, and diabetes were stratified by body mass index (BMI) into three reference groups (BMI ,25 kg/m2; BMI ?25 kg/m2 to ,30 kg/m2; and BMI ?30 kg/m2) to explore maximal apical FD (FDMaxApical). Multivariable linear regression models determined the relationship between FD and other parameters. Results: Included were 2547 participants (mean age, 68.7 years 6 9.1 [standard deviation]; 1211 men). FDMaxApical are in arbitrary units. FDMaxApical reference ranges for BMI 30 kg/m2 or greater (n = 163), 25 kg/m2 or greater to less than 30 kg/m2 (n = 206), and less than 25 kg/m2 (n = 235) were 1.203 6 0.06 (95% confidence interval: 1.194, 1.212), 1.194 6 0.06 (95% confidence interval: 1.186, 1.202), and 1.169 6 0.05 (95% confidence interval: 1.162, 1.176), respectively. In the entire cohort, adjusted for anthropometrics, trabeculation was higher in African American participants (standardized b [sb] = 0.09; P ? .001) and Hispanic participants (sb = 0.05; P = .013) compared with white participants and was also higher in African American participants compared with Chinese American participants (sb = 0.08; P = .01), and this persisted after adjustment for hypertension and LV size. Hypertension (sb = 0.07; P , .001), LV mass (sb = 0.22; P , .001), and wall thickness (sb = 0.27; P , .001) were positively associated with FDMaxApical even after adjustment. In the group with BMIs less than 25 kg/ m2, Chinese American participants had less trabeculation than white participants (sb = 20.15; P = .032). Conclusion: Fractal analysis of cardiac MR imaging data measures endocardial complexity, which helps to differentiate normal from abnormal trabecular patterns in healthy versus diseased hearts. Trabeculation is influenced by race and/or ethnicity and, more importantly, by cardiac loading conditions and comorbidities. Clinicians who interpret cine MR imaging data should expect slightly less endocardial complexity in Chinese American patients and more in African American patients, Hispanic patients, hypertensive patients, and those with hypertrophy.