INFLUENCE OF NIGHTTIME BLOOD-PRESSURE ON LEFT ATRIAL SIZE IN UNCOMPLICATED ARTERIAL SYSTEMIC HYPERTENSION

The aim of the study was to determine the relations of 24-h blood pres sure (BP) and its different phases with left atrial size. A total of 1 30 subjects (mean age 46 years) not taking cardiac drugs were studied by M-mode and Doppler echocardiography and ambulatory BP recording. Su bjects (excluding those with coronary artery or valvular heart disease , heart failure, or diabetes) were classified into two groups: 25 norm otensives and 105 hypertensives (history of antihypertensive treatment and office diastolic BP > 90 mm Hg). The two groups were comparable i n terms of sex, age, and heart rate, whereas body mass index, (P < .01 ), office BP, average 24-h BP, and average daytime and nighttime BP (a ll P < .00001) were higher in hypertensives. Hypertensives also had in creased left atrial dimension, left atrial dimension/aortic root ratio (both P < .001), and left ventricular mass (LV) indexed for height (P < .0001). Positive correlations of left atrial dimension were found w ith office BP, average 24-h, average daytime and nighttime systolic an d diastolic BP, LV mass index, and Doppler-derived E/A ratio. In a mul tivariate model that included potentially confounding factors, only bo dy mass index (standardized beta coefficient = 0.41, P < .00001), aver age nighttime diastolic BP (beta = 0.33, P < .00001), and male sex (be ta = 0.18, P < .01) were independent predictors of left atrial size in the pooled population. In conclusion, left atrial size is more closel y related to ambulatory, rather than office, BP measurements, and high average nighttime BP is a powerful marker of left atrial enlargement in arterial hypertension. (C) 1997 American Journal of Hypertension, L td.