Predictors of left ventricular mass and coronary artery calcium phenotypes

Abstract

Abstract Funding Acknowledgements Type of funding sources: Public Institution(s). Main funding source(s): National Medical Research Council, Ministry of Health, Singapore and the Lee Foundation Background Left ventricular (LV) mass and coronary artery calcium score (CACS) are both independent predictors of cardiovascular risk. There is paucity of data on the interplay of risk factors on LV mass in the presence or absence of subclinical coronary atherosclerosis. Purpose The objective of this present study was to explore the relationship of risk factors to indexed LV mass and CACS in a healthy Southeast-Asian population. Methods This study recruited volunteers with no known cardiovascular disease. LV mass, measured by cardiovascular magnetic resonance, was indexed to body surface area (LVMI), and CACS determined by non-contrast CT scanning. Blood pressure (BP) was measured via both office and ambulatory monitoring, and physical activity assessed through wearable devices. Analysis of LVMI was stratified into high, normal and low defined as more than one standard deviation away from the mean for each sex, with inter-group differences evaluated using chi-squared or ANOVA statistical tests. Subjects in each LVMI group were further subdivided by the presence and absence of coronary calcification (total 6 subgroups; LVMI/CACS phenotypes). Results A total of 880 subjects were included, including 428 males and 452 females. There was no significant difference in prevalence of coronary calcification across the LVMI groups for males, while females with high LVMI had significantly greater proportion of positive CACS (p = 0.036). Higher LVMI was observed in younger male subjects, but not in females. In both sexes, body mass index was positively associated with LVMI (p = 0.004 for males, p = 0.037 for females), but not CACS. Waist circumference was associated with higher LVMI in males only. Greater amounts of weekly self-reported exercise (p = 0.006) and daily calories burned (p = 0.022) were associated with increased LVMI for males only. However, wearable-derived measures of daily physical activity and step counts did not significantly affect LVMI or LVMI/CACS phenotypes in both sexes. BP was a strong predictor of LVMI in both sexes regardless of office or ambulatory readings, in both day and night-time. The association was also observed with LVMI/CACS phenotypes: higher systolic or diastolic BP was significantly associated with positive CACS across all risk groups. Notably, subjects with low LVMI and positive CACS were normotensive (office BP 129/82 for males, 123/77 for females). Higher HDL cholesterol levels correlated to absence of coronary calcification in males only (p = 0.010). In females, lower levels of total (p = 0.001) and LDL (p = 0.005) cholesterol were associated with absence of coronary calcification across all LVMI categories. Conclusion Only BP was strongly associated with LVMI and LVMI/CACS phenotypes in both sexes. There appears to be no correlation between physical activity and LVMI/CACS phenotypes. There is a need for causative studies to better evaluate the varying influence of risk factors on LVMI and CACS.