Risks of congestive heart failure are more accurately shown by an increased nighttime BP than with a traditional office BP measurement.
A new study by the researchers at Uppsala University revealed that a high blood pressure levels at night associates with an increased risk of congestive heart failure.
Congestive heart failure (CHF) is one of the most common, costly, disabling, and deadly diseases. Once diagnosed as having CHF, patients have a 1 in 3 chance of dying within 1 year and a 2 in 3 chance of dying within 5 years, according to background information in the article. The death rate associated with CHF exceeds that of most cancers, although recent reports suggest an improving prognosis. The predominant causes of CHF are hypertension and coronary heart disease, and high blood pressure (BP) is suggested to be the most important risk factor for CHF.
Previous studies have established that 24-hour BP measurements, which provide information that is not obtained from conventional office-based BP measurement, such as average BP over a 24-hour period and night-day patterns, are powerful predictors of cardiovascular illness and death. However, no previous studies have examined 24-hour ambulatory (as opposed to office-measured) BP as a predictor of CHF in persons free of CHF at baseline.
Erik Ingelsson, M.D., Ph.D., of Uppsala University, Uppsala, Sweden, and colleagues analyzed BP characteristics of 951 elderly men, free of CHF, valvular disease, and left ventricular hypertrophy at baseline between 1990 and 1995. They followed the participants 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.
Seventy men developed heart failure during follow-up. In analysis adjusted for antihypertensive treatment and established risk factors for CHF (heart attack, diabetes, smoking, body mass index, and serum cholesterol level), a 9-mm Hg increase in nighttime ambulatory diastolic blood pressure and the presence of 'nondipping' blood pressure (BP that is at least as high at night as during the day) were associated with an increased risk of CHF. Nighttime ambulatory diastolic blood pressure and nondipping blood pressure were also significant predictors of CHF after excluding all participants who had a heart attack before baseline or during follow-up.
Furthermore, a nondipping nighttime BP pattern increased the risk of CHF even after adjusting for conventional office BP measurement. 'This indicates that nighttime BP patterns may be important in development of CHF and that a traditional office BP measurement does not capture all of the increased risk that an increased nighttime BP conveys,' the authors write.
'Nighttime BP appears to convey additive risk information about CHF, but its clinical value remains to be established in future studies.'