RELATIONS OF PLASMA ALDOSTERONE CONCENTRATION TO CARDIAC STRUCTURE AND FUNCTION: ARE THERE ANY ETHNIC-RELATED DIFFERENCES?

Abstract

Objective: Plasma aldosterone concentration (PAC) is related to left ventricular hypertrophy (LVH) and diastolic dysfunction in primary hyperaldosteronism but conflicting data exists in primary hypertension. Here we investigated whether this association might differ in hypertensive subjects of African-origin background (black) vs Caucasian (white). Design and method: Subjects with hypertension and self-defined ethnicity (SDE) as black or white whose clinical assessment was not suggestive of secondary forms of hypertension and with an aldosterone/renin ratio < 90 pmol/mU were recruited in London (UK) and Pisa (Italy). Transthoracic echocardiography was used to calculate left ventricular mass index (LVMI) and diastolic function using the ratio of early (E)) transmitral filling velocity to tissue Doppler early diastolic velocity (E/e’). Results: 167 black (51% male) and 273 white (69% male) subjects of whom 55% and 73% on pharmacological treatment were recruited. Compared to white individuals, black subjects had higher blood pressure (BP) (mean ± SD) (153/93 ± 15/12 mmHg vs 139/88 ± 15/11 mmHg) and lower prevalence of dyslipidaemia (9 % vs 38 %, both P < 0.05) but the two groups were similar for age, prevalence of diabetes, smoking, duration of hypertension. Compared to white subjects, black individuals had lower renin and PAC level (42.4 ± 11.2mU/L vs 79.5 ± 12.7 mU/L and 312 ± 26.5 pmol/L vs 420 pmol/L respectively) while LVMI and E/E’ were greater (95.9 ± 25.2 g/m2 vs 88.7 ± 20.5 g/m2 and 9.1 ± 2.8 vs 7.8 ± 2.4 respectively) all P < 0.001. In the entire population we found a significant interaction between ethnicity and PAC in relation to LVMI and E/e’. After stratifying the population according to SDE, PAC positively correlated with LVMI (R2 0.249, P = 0.01) and E/e’ (R2 0.207, P = 0.009) in black but not in white subjects. Multivariate adjustment for sex, BP, diabetes, dyslipidaemia, heart rate, pharmacological treatment, body mass index did not alter the relationship. Conclusions: Aldosterone is related to cardiac remodelling and diastolic function in patients with primary hypertension of African origin. The reasons behind the ethnic difference needs to be elucidated.