Age, increased left ventricular mass, and lower regional myocardial perfusion are related to greater extent of myocardial dyssynchrony in asymptomatic individuals: the multi-ethnic study of atherosclerosis.

BACKGROUND Age and left ventricular (LV) hypertrophy are risk factors for the development of LV dysfunction and congestive heart failure. Our goal was to study the relationships of LV mass and age with myocardial dyssynchrony among asymptomatic participants of the Multi-Ethnic Study of Atherosclerosis. METHODS AND RESULTS A total of 1100 individuals underwent tagged magnetic resonance imaging. Regional LV function was analyzed with the use of harmonic phase imaging. Time to peak systolic circumferential strain and strain rate were measured in 12 segments, and myocardial dyssynchrony was expressed as the SD of time to peak strain and strain rate. Relationships of age, LV mass, and myocardial perfusion with timing of strain, strain rate, and dyssynchrony were studied. There was a positive relationship between age and time to peak strain before (regression coefficient=0.37 ms/year of age; 95% confidence interval, 0.05 to 0.70; P=0.025) and after adjustment for demographic characteristics and risk factors (P=0.007). Positive associations between age and SD of time to peak strain (regression coefficient=0.33 ms/year of age; P=0.002) and SD of time to peak systolic strain rate were documented (P=0.045). Importantly, we found that LV mass index is directly related to time to peak strain (P<0.001), time to peak strain rate, and the SD of time to strain rate (P=0.001 for all). Finally, decreased myocardial perfusion at rest was associated with delayed contraction and increased extent of dyssynchrony. CONCLUSIONS In asymptomatic individuals, age, increased LV mass, and decreased myocardial perfusion are related to delayed myocardial contraction and greater extent of dyssynchrony. Increased dyssynchrony may mediate the association of myocardial dysfunction with age and LV hypertrophy.