Low cardiovascular risk is associated with favorable left ventricular mass, left ventricular relative wall thickness, and left atrial size: the CARDIA study

Background: Echocardiographic measures of left ventricular (LV) mass and relative wall thickness and left atrial (LA) size predict future cardiovascular morbidity and mortality. The aim of this study was to compare young adults with low cardiovascular risk (body mass index, 18.5-24.9 kg/m(2); blood pressure < 120/80 mmHg; no tobacco use, no diabetes, and physical fitness) with those without these characteristics with regard to LV mass and relative wall thickness and LA size, to determine the protective effect of a healthy lifestyle on the development of these characteristics.

Methods: Cross-sectional assessment of 4059 black and white men and women aged 23 to 35 years in the Coronary Artery Risk Development in Young Adults (CARDIA) study at the year 5-examination, when risk factors were measured, and echocardiography to assess LV mass and relative wall thickness were performed. Physical fitness was measured at baseline using a symptom-limited maximal treadmill test. All other covariates were measured concurrently with echocardiography.

Results: Gender, body mass index, and systolic blood pressure were associated with LV mass and relative wall thickness and LA size in multivariate models. Additional correlates of LV mass/height(2.7) ratio were tobacco use, resting heart rate (inverse), self-reported physical activity, gender (male higher), and age. Age was associated with LV relative wall thickness but not other measures of LV size. Additional correlates of LA diameter/height ratio were tobacco use, resting heart rate (inverse), serum glucose, and self-reported physical activity. Seven hundred ninety of 4059 subjects (19%) were classified as having low risk; black race was less likely in the low-risk group. Those with low risk had lower LV mass/height(2.7) ratios (32.0 vs 34.6 g/m(2.7), P < .0001), better LV relative wall thickness (0.33 vs 0.35, P < .0001), and lower LA diameter/height ratios (2.02 vs 2.08 cm/m, P < .01).

Conclusions: A low cardiovascular risk profile in young adulthood is associated with more favorable LV mass, LV relative wall thickness, and LA size. This may be one mechanism of lifestyle protection against cardiovascular morbidity and mortality.