Relation between diurnal variation of blood pressure and left ventricular mass in a Chinese population

In western populations, patients with hypertension who have a nocturnal decrease in blood pressure (BP) may have less left ventricular (LV) hypertrophy and cardiovascular morbidity than those without a diurnal variation in BP. To further examine this association between nocturnal BP reduction and LV mass index, we studied 720 normotensives (< 140/90 mm Hg), 380 borderline hypertensives (140 to 159/90 to 94 mm Hg), and 582 hypertensives (> or = 160/95 mm Hg) from Taiwan and Quemoy island by using 24-hour ambulatory BP monitoring and 2-dimensional echocardiography to obtain LV mass index during a community-based cardiovascular survey. After controlling for age, sex, height, weight, daytime BP, and daytime heart rate, the nocturnal reduction of systolic BP was found to associate weakly with LV mass index, for the whole population (partial correlation coefficient = -0.06, p < 0.05), as well as for the patients with hypertension (partial correlation coefficient = -0.09, p < 0.05), but these associations were eliminated when 24-hour BP and heart rate were accounted for. The average and percent nocturnal decrease of systolic BP (mean +/- SD; mm Hg, [%]) of 3.2 +/- 5.9 (2.7 +/- 4.8%); 3.3 +/- 7.3 (2.4 +/- 5.4%); and 4.6 +/- 9.0 (3.0 +/- 6.1%) in normotensives, borderline hypertensives, and hypertensives, respectively, was smaller than that found in previous studies. Hence, in this large Chinese population, a small nocturnal BP drop was found and it was only weakly associated with LV mass index. These results emphasize the general need for ambulatory BP reference values based on internal controls.