Diurnal Blood Pressure Pattern and Risk of Congestive Heart Failure

Abstract

Context. High blood pressure (BP) is the most important risk factor for congestive heart failure (CHF) at a population level, but the relationship of an altered diurnal BP pattern to the risk of subsequent CHF is unknown. Objectives. To explore 24-hour ambulatory BP characteristics as predictors of CHF incidence and to investigate whether altered diurnal BP patterns confer any additional risk information beyond that provided by conventional office BP 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 until the end of 2002. Twenty-four-hour ambulatory BP monitoring was performed at baseline, and the BP variables were analyzed as predictors of subsequent CHF. The main outcome measure was first hospitalization for CHF. Results. Seventy men developed CHF 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 BP (hazard ratio [HR], 1.26; 95% confidence interval [CI], 1.02–1.55) and the presence of “nondipping” BP (night-day ambulatory BP ratio ≥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 Bps, nondipping BP remained a significant predictor of CHF (HR, 2.21; 95% CI, 1.12–4.36 vs normal night-day pattern). Nighttime ambulatory diastolic BP and nondipping BP 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 BP appears to convey additional risk information about CHF beyond office-measured BP and other established risk factors for CHF. The clinical value of this association remains to be established in future studies.—Ingelsson E, Bjorklund-Bodegard K, Lind L, et al. Diurnal blood pressure pattern and risk of congestive heart failure. JAMA. 2006;295:2859–2866. Comment. Ambulatory BP monitoring provides information that is not obtained from conventional office-based BP measurement, such as mean BP over a 24-hour period and circadian BP patterns. Staessen et al1demonstrated that a nondipping pattern of BP (night-day ambulatory BP ratio ≥1) and nighttime BP more accurately predicted cardiovascular events than daytime BP. A reduced circadian BP variation is a common finding in CHF patients. The association of diastolic dysfunction with increased diastolic BP and nondipping in patients with hypertension and type 2 diabetes is also known. The primary aim of this study was to determine what characteristics of the 24-hour ambulatory BP measurements best predicted new-onset CHF, and how these characteristics of the 24-hour ambulatory BP measurements compared with office measurements. The prospective, community-based, observational cohort included 951 elderly men free of CHF, valvular disease, and left ventricular hypertrophy at baseline followed for a median of 9.1 years. Twenty-four-hour ambulatory BP monitoring along with office-based BP measurements were performed at baseline, and the BP variables, including nondipping pattern, were analyzed as predictors of subsequent CHF. Seventy men developed CHF during follow-up, with an incidence rate of 8.6 per 1000 person-years at risk. After adjusting 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 BP and the presence of nondipping BP were associated with an increased absolute risk of CHF. A 5-mm Hg increment in nighttime ambulatory diastolic BP was associated with a 13%–25% increased risk of CHF. After adjusting for office-measured systolic and diastolic Bps, nondipping pattern remained a significant predictor of CHF. The incidence of CHF was 15 cases higher per 1000 person-years at risk for those with nondipping vs normal night—day BP pattern. Nighttime ambulatory diastolic BP and nondipping BP were also significant predictors of CHF even after exclusion of all participants who had an acute myocardial infarction before baseline or during follow-up. The few limitations of this study include limited generalizability to women and other age or ethnic groups, inadvertent exclusion of nonhospitalized patients with mild CHF, and unknown impact of BP pattern on systolic vs diastolic HF. The pathophysiologic mechanism behind this association is not yet clear, but the authors speculate that endothelial dysfunction and/or increased sympathetic activity may be dysfunctions playing significant roles. Reversed circadian BP pattern (nondipping) may be important per se or may be an indicator of an important trait like sleep apnea. Previous studies have shown an association of nondipping nocturnal Bps and ambulatory BP readings with both cardiovascular disease incidence and left ventricular hypertrophy, and these findings with regard to CHF are consistent. The authors are rightfully cautious about the clinical implications of these findings, but they may provide additional clues to understanding the progression from hypertension to CHF.