Blood pressure variability is significantly associated with ECG left ventricular mass in normotensive Africans: The SABPA Study

Abstract

The prognostic significance of blood pressure (BP) variability has lately enjoyed considerable attention. The need for early markers of cardiovascular dysfunction is imperative in black South Africans who have a significant risk for cardiovascular disease. We therefore compared 24-h BP variability with various traditional and advanced BP measurements, regarding their association with sub-clinical organ damage in black and white South Africans. The study included 409 African and Caucasian teachers aged 25-60 yrs. We measured office BP, 1-min continuous (finger) BP, ambulatory BP, BP reactivity and determined weighted 24-h BP variability. Albumin-to-creatinine ratio, Cornell product and carotid cross-sectional wall area (CSWA) were measures of organ damage. Africans had higher 24-h BP, BP variability, BP reactivity and sub-clinical organ damage (Po0.001). Correlations of BP variability with organ damage were overall weak when compared with other BP measurements. In normotensive groups, we found an independent association of 24-h systolic BP (SBP) variability with Cornell product only in Africans (r¼0.37; P¼0.01), confirmed in multiple regression models, with 24-h SBP included in the model. Only in hypertensive Caucasians, a significant correlation between CSWA and 24-h SBP variability was evident (r¼0.30; P¼0.01), although CSWA indicated stronger correlations with office or 24-h SBP than 24-h SBP variability. To conclude, 24-h SBP variability could potentially be an effective measure for the early detection of normotensive Africans at increased risk for the development of cardiovascular complications. Its usefulness based on associations with target organ damage in hypertensive groups seems to be less than traditional office or 24-h BP measurements. Hypertension Research (2011Research ( ) 34, 1127Research ( -1134 doi:10.1038/hr.2011; published online 28 July 2011Keywords: albumin-to-creatinine ratio; ethnicity; intima-media thickness; left ventricular hypertrophy INTRODUCTIONThe prognostic significance of blood pressure (BP) variability has lately enjoyed considerable attention in the literature. [1][2][3][4][5][6][7][8][9][10] Where some papers emphasize the importance of BP variability in prediction of risk of vascular events, 1,2,6,9 others question its prediction of cardiovascular outcome. 4,5,10 Despite this upsurge of recent papers, consistent evidence over the past three decades lends support that both target organ damage and the rate of cardiovascular events of hypertensive patients are significantly and independently related to the degree of BP variability. [11][12][13][14][15] A limitation of many of these papers is that either BP variability alone was investigated, or various measures of BP variability (such as s.d. of 24-h BP, average real variability index 16 and weighted 24-h BP s.d. 17 ) were being compared, regarding the strength of their association with target organ damage.The question therefore arises how BP variability would benchmark against a comprehensive range of both traditional and advanced

Blood Pressure Variability: Prognostic Value and Therapeutic Implications

“…The study included 409 African and Caucasian teachers aged 25-60 years showing a positive correlation between 24 hour systolic BPV and markers of left ventricular hypertrophy in African but not 6 ISRN Hypertension Caucasian normotensive subjects. Considering this association, the authors stress out that the assessment of shortterm BPV could potentially add to the early detection of normotensive Africans at increased risk for the development of cardiovascular complications [35]. Data from Ozawa et al also suggest that increased shortterm BPV estimated by ABPM represents a coronary risk factor in diabetic hypertensive patients [36].…”

“…In addition to vascular damage, short-term BPV has been associated with left ventricular hypertrophy in normotensive Africans in the SABPA Study [35]. The study included 409 African and Caucasian teachers aged 25-60 years showing a positive correlation between 24 hour systolic BPV and markers of left ventricular hypertrophy in African but not 6 ISRN Hypertension Caucasian normotensive subjects.…”

Normotension, blood pressure variability and early target organ damage

“…The burden of disease attributable to high BP has already been established in normotension (BPo140/90 mm Hg). 1 The data of Schutte et al 10 demonstrate that BP variability is involved in the development of target organ damage in normotensive blacks. African populations are known to have a two-to threefold greater prevalence of left ventricular hypertrophy, 11 which contributes more to the risk of CV mortality in AfricanAmericans than in Caucasians.…”

“…In this issue of Hypertension Research, Schutte et al 10 report interesting data that correlate short-term BP variability and electrocardiographic left ventricular mass in normotensive African patients, including both normo-and hypertensive subjects. As a measure of short-term reading-to-reading BP variability, the authors used averages of daytime and nighttime SDs weighted for the duration of the daytime and nighttime intervals, as proposed previously.…”

Blood pressure variability and its implications in people of African descent

“…For example, normotensive individuals with a family history of hypertension have decreased baroreceptor activity, which contributes to BP variability. The study by Schutte et al 5 did not indicate any family history of hypertension in their subjects.…”