Rural and Urban Japanese Populations

Background It has been suggested that echocardiographically determined left ventricular mass (LVM) is useful in the prediction of hypertension. To examine the relation between LVM and subsequent blood pressure (BP) change, a 6to 8-year follow-up was conducted in adult Japanese men. Methods and Results LVM was determined by M-mode echocardiography using the American Society of Echocardiography formula among 354 normotensive men aged 30 to 59 years from a rural community (n= 193) and from urban companies (n= 161) in Japan between 1979 and 1983. BP was remeasured 6 to 8 years after baseline in 148 rural men (77%) and 127 urban men (79%). For men whose BP was remeasured, the mean+SD LVM index (LVM/body surface area [g/m2]) at baseline was 117±22 in rural men and 99+15 in urban men (the difference, P<.001). For both populations, LVM index was positively associated with age and physical activity but not with body mass index. Associations of LVM index with usual alcohol intake and initial BPs were generally weak. According to linear regression analyses after controlling for these covariates at baseline, a 20-g/m2 greater LVM index at baseline was associated with a 5 mm Hg increase in systolic and a 4 mm Hg increase in diastolic BP during the subsequent 6 to 8 years for urban men. A 1-mm greater average ventricular wall thickness was associated with a similar BP increase. For rural men, positive associations of LVM index with BP increase existed but were weak. The weaker association between LVM index and BP increase in rural compared with urban men was probably the result of effects of higher physical activity, leading to a larger left ventricular internal dimension. The increase in systolic and diastolic BPs over the 6 to 8 years of observation was significantly related to baseline LVM index in rural and urban men with a smaller internal dimension (rural men, <49 mm; urban men, c47 mm) but not in those with larger dimensions. Conclusions An increased LVM index predicts subsequent BP increase in middle-aged normotensive men in the presence of a normal or small internal dimension. (Circulation. 1994; 89:1717-1724.)