Response of day-to-day home blood pressure variability by antihypertensive drug class after transient ischemic attack or nondisabling stroke

Abstract

Background and purpose: Visit-to-visit variability in systolic blood pressure (SBP) is associated with an increased risk of stroke and was reduced in randomized trials by calcium channel blockers and diuretics but not by renin-angiotensin system inhibitors. However, time of day effects could not be determined. Day-to-day variability on home BP readings predicts stroke risk and potentially offers a practical method of monitoring response to variability-directed treatment.

Methods: SBP mean, maximum, and variability (coefficient of variation=SD/mean) were determined in 500 consecutive transient ischemic attack or minor stroke patients on 1-month home BP monitoring (3 BPs, 3× daily). Hypertension was treated to a standard protocol. Differences in SBP variability from 3 to 10 days before to 8 to 15 days after starting or increasing calcium channel blockers/diuretics versus renin-angiotensin system inhibitors versus both were compared by general linear models, adjusted for risk factors and baseline BP.

Results: Among 288 eligible interventions, variability in SBP was reduced after increased treatment with calcium channel blockers/diuretics versus both versus renin-angiotensin system inhibitors (-4.0 versus 6.9 versus 7.8%; P=0.015), primarily because of effects on maximum SBP (-4.6 versus -1.0 versus -1.0%; P=0.001), with no differences in effect on mean SBP. Class differences were greatest for early-morning SBP variability (3.6 versus 17.0 versus 38.3; P=0.002) and maximum (-4.8 versus -2.0 versus -0.7; P=0.001), with no effect on midmorning (P=0.29), evening (P=0.65), or diurnal variability (P=0.92).

Conclusions: After transient ischemic attack or minor stroke, calcium channel blockers and diuretics reduced variability and maximum home SBP, primarily because of effects on morning readings. Home BP readings enable monitoring of response to SBP variability-directed treatment in patients with recent cerebrovascular events.

Keywords: antihypertensive agents; home blood pressure monitoring; stroke.

Figure 1. Distribution of changes in mean, maximum and variability in SBP after intervention with CCBs/diuretics versus RAS inhibitors.

Distributions are presented as frequency of interventions resulting in a % change in mean SBP (A), max SBP (B) and rCV (C), comparing initiation or dose increases of CCBs or diuretics versus RAS inhibitors.

Figure 2. Differences between change in variability or maximum SBP after initiation of drugs associated with lower SBP variability, higher SBP variability or a combination of both.

Results presented are mean percentage change in maximum SBP or residual coefficient of variation (RCV) in SBP for days 8-15 after starting or increasing each treatment compared to 3-10 days before the intervention, adjusted for age, gender, diabetes, history of hypertension, current smoking, family history of stroke, dyslipidaemia, atrial fibrillation, creatinine baseline mean SBP and baseline maximum SBP or SBP-rCV. P-values and confidence intervals are derived from general linear models, comparing drugs associated with lower SBP variability (“low”) with drugs associated with higher SBP variability (“high”).