600 IS BLOOD PRESSURE LOAD ASSOCIATED, INDEPENDENTLY OF BLOOD PRESSURE LEVEL, WITH TARGET ORGAN DAMAGE?

Abstract

Background: Current guidelines propose diagnosis of ambulatory hypertension based on 24-hour blood pressure (BP) levels. We examined whether blood pressure load (BPL) would be associated, independently of 24-hour BP level, with hypertensive target organ damage. Methods: We recruited 967 subjects (483 men, mean age 51.0 years) who were not taking antihypertensive drugs for at least 2 weeks. All subjects had 24-hour ambulatory BP measured. BPL was defined as the percentage of abnormally elevated BP readings during the daytime and nighttime. Brachial-ankle pulse wave velocity (Ba-PWV) and carotid-femoral pulse wave velocity (Cf-PWV) was measured. Left ventricular mass was determined and LVMI was calculated. Albumin/creatinine ratio (ACR) of a single first-morning urine wasmeasured. Results: In 967 subjects, 652 had hypertension, of whom 91 reported previous use of antihypertensive drugs. Systolic and diastolic BPL had a skewed distribution. In univariate analyses, ba-PWV (13.8vs.14.7vs.15.5 m/s), cf-PWV (7.3 vs. 7.8 vs.8.4 m/s), LVMI (89.3 vs. 95.5 vs.102.1 g/m2) and urinary ACR (0.48vs. 0.60vs. 0.75 mg/mmol) all increased (P<0.001) across the tertiles of systolic BPL. After adjustment for potential covariables, the trends of ba-PWV, cf-PWV, LVMI and urinary ACR across the tertiles remained to be significant (P<0.001). However, when 24-hour SBP level was additionally added into the models, the difference was not significant (P>0.52) between the tertiles.Logistic regression analysis forwarded consistent information. Similar results were observed for diastolic BPL. Conclusions: BPL was associated with target organ damage, but not independently of 24-hour BP level.