Predicting Cardiovascular Risk Using Conventional vs Ambulatory Blood Pressure in Older Patients With Systolic Hypertension

TLDR

Ambulatory blood‑pressure monitoring requires prospective validation to determine its prognostic value compared with conventional measurements in older patients with isolated systolic hypertension, as investigated in the Syst‑Eur trial. The study aimed to compare the prognostic significance of conventional versus ambulatory BP measurement in this population. A total of 808 patients aged ≥60 years with untreated systolic BP 160–219 mm Hg were randomized to nitrendipine (± enalapril or hydrochlorothiazide) or placebo, with conventional BP obtained as the mean of six seated readings and ambulatory BP recorded intermittently over 24 hours. Ambulatory systolic BP, particularly nighttime values and the night‑to‑day ratio, predicted cardiovascular events more accurately than conventional BP, which showed no association with risk; ambulatory BP remained a significant predictor even after treatment.

Abstract

The clinical use of ambulatory blood pressure (BP) monitoring requires further validation in prospective outcome studies.To compare the prognostic significance of conventional and ambulatory BP measurement in older patients with isolated systolic hypertension.Substudy to the double-blind placebo-controlled Systolic Hypertension in Europe (Syst-Eur) Trial, started in October 1988 with follow up to February 1999. The conventional BP at randomization was the mean of 6 readings (2 measurements in the sitting position at 3 visits 1 month apart). The baseline ambulatory BP was recorded with a noninvasive intermittent technique.Family practices and outpatient clinics at primary and secondary referral hospitals.A total of 808 older (aged > or =60 years) patients whose untreated BP level on conventional measurement at baseline was 160 to 219 mm Hg systolic and less than 95 mm Hg diastolic.For the overall study, patients were randomized to nitrendipine (n = 415; 10-40 mg/d) with the possible addition of enalapril (5-20 mg/d) and/or hydrochlorothiazide (12.5-25.0 mg/d) or to matching placebos (n = 393).Total and cardiovascular mortality, all cardiovascular end points, fatal and nonfatal stroke, and fatal and nonfatal cardiac end points.After adjusting for sex, age, previous cardiovascular complications, smoking, and residence in western Europe, a 10-mm Hg higher conventional systolic BP at randomization was not associated with a worse prognosis, whereas in the placebo group, a 10-mm Hg higher 24-hour BP was associated with an increased relative hazard rate (HR) of most outcome measures (eg, HR, 1.23 [95% confidence interval [CI], 1.00-1.50] for total mortality and 1.34 [95% CI, 1.03-1.75] for cardiovascular mortality). In the placebo group, the nighttime systolic BP (12 AM-6 AM) more accurately predicted end points than the daytime level. Cardiovascular risk increased with a higher night-to-day ratio of systolic BP independent of the 24-hour BP (10% increase in night-to-day ratio; HR for all cardiovascular end points, 1.41; 95% CI, 1.03-1.94). At randomization, the cardiovascular risk conferred by a conventional systolic BP of 160 mm Hg was similar to that associated with a 24-hour daytime or nighttime systolic BP of 142 mm Hg (95% CI, 128-156 mm Hg), 145 mm Hg (95% CI, 126-164 mm Hg) or 132 mm Hg (95% CI, 120-145 mm Hg), respectively. In the active treatment group, systolic BP at randomization did not significantly predict cardiovascular risk, regardless of the technique of BP measurement.In untreated older patients with isolated systolic hypertension, ambulatory systolic BP was a significant predictor of cardiovascular risk over and above conventional BP.