Night-time systolic blood pressure and subclinical cerebrovascular disease: the Cardiovascular Abnormalities and Brain Lesions (CABL) study

Abstract

Aims: Although ambulatory blood pressure (BP) is a better predictor of cardiovascular outcomes than office BP, its association with subclinical cerebrovascular disease is not clarified. We investigated the associations of office and ambulatory BP values with subclinical cerebrovascular disease in a population based, predominantly elderly cohort without prior stroke.

Methods and results: Eight hundred and twenty-eight participants underwent 24-h ambulatory BP monitoring (ABPM), 2D echocardiography and brain magnetic resonance imaging in the Cardiac Abnormalities and Brain Lesion (CABL) study. Daytime, night-time, and 24-h BPs, nocturnal dipping pattern, morning surge (MS), and 24-h variability were assessed. Subclinical cerebrovascular disease was defined as silent brain infarcts (SBIs) and white matter hyperintensity volume (WMHV). The association of BP measures with the presence of SBI and upper quartile of log-WMHV (log-WMHV4) was analysed. SBIs were detected in 111 patients (13.4%). Mean log-WMHV was -0.99 ± 0.94. In multivariable analysis, only night-time systolic BP (SBP) was significantly associated with SBI [odds ratio (OR) 1.15 per 10 mmHg, P = 0.042], independent of cardiovascular risk factors, and pertinent echocardiographic parameters. Although daytime, night-time, 24-h BPs, and non-dipping pattern were all significantly associated with log-WMHV4 (all P < 0.05), night-time SBP showed the strongest association (OR 1.21 per 10 mmHg, P = 0.003) and was the sole independent predictor when tested against the other BP parameters. Office BP measures, MS, and BP variability were not associated with subclinical cerebrovascular disease in adjusted analyses.

Conclusion: Elevated night-time SBP is strongly associated with subclinical cerebrovascular disease. Night-time SBP by ABPM allows to identify individuals at higher risk of hypertensive brain injury.

Keywords: ambulatory blood pressure monitoring; night-time blood pressure; silent brain infarcts; white matter hyperintensity.

Figure 1

Association of night-time SBP subgroups with log-WMHV4. Reference: night-time SBP <120 mmHg. (A) Univariable analyses. (B) Multivariable Model 1: adjusted for age, race, hypertension, atrial fibrillation, left ventricular mass index, left atrial diameter index, and interval between ABPM and brain MRI. (C) Multivariable Model 2: Model 1 plus BP dipping pattern. ABPM, ambulatory blood pressure monitoring; CI, confidence interval; MRI, magnetic resonance imaging; OR, odds ratio; SBP, systolic blood pressure; WMHV, white matter hyperintensity volume. ^∗P<0.01 and ^†P<0.05 vs. night-time SBP <120 mmHg.