Echocardiographic measures of left ventricular structure and their relation with rest and ambulatory blood pressure in blacks and whites in the United Kingdom

Abstract

Objectives. This study attempted to determine whether people of black African descent have more left ventricular hypertrophy than those of white European descent and whether this can be explained by rest or ambulatory blood pressure.Background. Mortality associated with hypertension is higher in black populations than among whites, but differences in morbidity and their associations with blood pressure are inconsistent.Methods. We examined 1,166 black and white men and women 40 to 64 years old in a community survey in London, United Kingdom. Echocardiograms were obtained for all subjects and ambulatory blood pressure recordings for 319.Results. Adjusted for body size, ventricular septal thickness was greater in blacks than whites (p < 0.05), and cavity dimension was smaller (p < 0.05). In men, ventricular septal thickness was >10 mm for 32% of whites and 53% of blacks; for women these figures were 14% and 38%, respectively. Relative wall thickness was greater in blacks (p < 0.01 for men and women), but left ventricular mass index was similar in the two ethnic groups. In men, hypertension resulted in an increase in wall thickness in both ethnic groups, but cavity dimension decreased in blacks and increased in whites. Wall thickness was higher in blacks than in whites for equivalent levels of either rest (p = 0.05) or ambulatory (p = 0.007) blood pressure.Conclusions. Left ventricular mass index may not be valid for comparisons between ethnic groups because this derived measure does not take into account ethnic differences in ventricular structural response to hypertension. Interventricular wall thickness may be more valid. Using this measure, we demonstrate greater ventricular hypertrophy in blacks than in whites, unexplained by differences in either rest or ambulatory blood pressure. The pattern of ventricular hypertrophy observed in blacks is associated with an increased mortality risk. Conventional blood pressure thresholds for instituting antihypertensive treatment may be too conservative for people of black African descent.