Related Experiment Videos
Ethnic differences in the hypertensive heart and 24-hour blood pressure profile
1Peart-Rose Clinic, Department of Cardiology, St Mary's Hospital, Imperial College, London, UK.
Insights
Black hypertensives have greater left ventricular hypertrophy than white hypertensives, not explained by 24-hour blood pressure. Nocturnal blood pressure dipping patterns, not just overall levels, may explain these differences.
Area of Science:
- Cardiology
- Hypertension Research
- Clinical Physiology
Background:
- Black hypertensive individuals exhibit greater left ventricular hypertrophy (LVH) compared to white hypertensives.
- Previous studies matched groups by clinic blood pressure (BP), potentially underestimating mean 24-hour BP in Black hypertensives due to attenuated nocturnal BP dip.
Purpose of the Study:
- To determine if differences in LVH between Black and white hypertensives are explained by mean 24-hour BP.
- To investigate the relationship between BP profiles, including nocturnal dipping, and LVH in these groups.
Main Methods:
- 92 treatment-naive hypertensive patients (46 Black, 46 white) underwent 24-hour ambulatory BP monitoring and echocardiography.
- Participants were matched for age, gender, and mean 24-hour BP.
Main Results:
- Despite similar mean 24-hour BP, Black hypertensives showed a significantly smaller nocturnal BP dip (8/8 mm Hg) compared to white hypertensives (16/13 mm Hg).
- Mean left ventricular mass index (LVMI) was significantly greater in Black hypertensives (130 g/m²) than in white hypertensives (107 g/m²).
- LVMI was independently related to mean daytime BP and mean nocturnal BP dip in Black subjects, but only to mean daytime BP in white subjects.
Conclusions:
- Increased LVH in Black hypertensives is not solely explained by mean 24-hour BP differences.
- The nocturnal BP dipping pattern, rather than 24-hour BP, appears more critical in influencing LVH in Black hypertensives, suggesting BP profile is key to understanding racial disparities in LVH.
Abstract:
Black hypertensive persons have been observed to have a greater degree of left ventricular hypertrophy than white hypertensives. However, previous studies have matched groups for blood pressure (BP) measured in the clinic, and it has been demonstrated that black hypertensives have an attenuated nocturnal BP dip. Clinic BPs may thus underestimate mean 24-hour BP in this group. To investigate whether the differences in left ventricular hypertrophy can be accounted for by the greater mean 24-hour BP in black hypertensives, 92 previously untreated hypertensives were studied with 24-hour ambulatory BP monitoring and echocardiography. The 46 black hypertensives (24 men and 22 women) were matched with the 46 white hypertensives for age, gender, and mean 24-hour BP. Despite similar mean 24-hour BPs (blacks, 142/93 mm Hg; whites, 145/92 mm Hg; P=.53/.66), the black group had a smaller mean nocturnal dip than the white group (blacks, 8/8 mm Hg; whites, 16/13 mm Hg; P<.01). In addition, mean left ventricular mass index (LVMI) was greater (blacks, 130 g/m2; whites, 107 g/m2; P<.001). Mean 24-hour systolic BP was significantly related to LVMI in both groups (blacks, r=.45, P<.01; whites, r=.56, P<.01). However, systolic BP dip correlated inversely with LVMI only in the black group (blacks, r=-.30, P<.04; whites, r=.05, P=.76). In a multiple regression model, LVMI was independently related to both mean daytime BP and mean nocturnal BP dip in black subjects but only to mean daytime BP in white subjects. In conclusion, the increased left ventricular hypertrophy observed in black hypertensives compared with white hypertensives is not accounted for by differences in mean 24-hour BP. However, LVMI in black hypertensives appears to be more dependent on nocturnal BP than that in white hypertensives; this, coupled with the attenuated BP dip in black hypertensives, suggests that the BP profile rather than 24-hour BP may be important in determining the differences in left ventricular hypertrophy.