Context: High blood pressure is the most important risk factor for congestive heart failure (CHF) at a population level, but the relationship of an altered diurnal blood pressure pattern to risk of subsequent CHF is unknown.
Objectives: To explore 24-hour ambulatory blood pressure characteristics as predictors of CHF incidence and to investigate whether altered diurnal blood pressure patterns confer any additional risk information beyond that provided by conventional office blood pressure measurements.
Design, setting, and participants: Prospective, community-based, observational cohort in Uppsala, Sweden, including 951 elderly men free of CHF, valvular disease, and left ventricular hypertrophy at baseline between 1990 and 1995, followed up until the end of 2002. Twenty-four-hour ambulatory blood pressure monitoring was performed at baseline, and the blood pressure variables were analyzed as predictors of subsequent CHF.
Main outcome measure: First hospitalization for CHF.
Results: Seventy men developed heart failure during follow-up, with an incidence rate of 8.6 per 1000 person-years at risk. In multivariable Cox proportional hazards models adjusted for antihypertensive treatment and established risk factors for CHF (myocardial infarction, diabetes, smoking, body mass index, and serum cholesterol level), a 1-SD (9-mm Hg) increase in nighttime ambulatory diastolic blood pressure (hazard ratio [HR], 1.26; 95% confidence interval [CI], 1.02-1.55) and the presence of "nondipping" blood pressure (night-day ambulatory blood pressure ratio > or =1; HR, 2.29; 95% CI, 1.16-4.52) were associated with an increased risk of CHF. After adjusting for office-measured systolic and diastolic blood pressures, nondipping blood pressure remained a significant predictor of CHF (HR, 2.21; 95% CI, 1.12-4.36 vs normal night-day pattern). Nighttime ambulatory diastolic blood pressure and nondipping blood pressure were also significant predictors of CHF after exclusion of all participants who had an acute myocardial infarction before baseline or during follow-up.
Conclusions: Nighttime blood pressure appears to convey additional risk information about CHF beyond office-measured blood pressure and other established risk factors for CHF. The clinical value of this association remains to be established in future studies.