CHICAGO — Treated hypertensive patients who have either extreme or very slight dips in nighttime blood pressure are at greater cardiovascular risk than are those with moderate dips, according to a study in 1,472 patients.
Prior research has shown that people whose blood pressure fails to dip at night (“nondippers”) are at much higher risk for cardiovascular events than are patients whose BP follows the normal diurnal pattern and falls by 10%–20% during sleep. The new data extend these findings to include “extreme dippers,” or those whose nighttime systolic and/or diastolic BP dips by at least 20%.
“Circadian blood pressure pattern influences cardiovascular outcome in treated hypertension and its evaluation allows a better prognostic stratification and may suggest a more appropriate pharmacological management,” lead investigator Dr. Sante D. Pierdomenico and associates reported in a poster at the annual meeting of the American Society of Hypertension.
The investigators studied 388 patients with a dipper BP pattern (systolic and diastolic nighttime BP reduction of at least 10% and less than 20%), 745 with a nondipper BP pattern (systolic and/or diastolic reduction of less than 10%), and 339 with an extreme-dipper BP pattern. Blood pressure measurements were taken with a 24-hour ambulatory blood pressure monitoring system.
Nondippers (mean age 61 years) were significantly older than dippers (58 years) or extreme dippers (55 years), and were more likely to have diabetes (8%) than were dippers (4.4%) or extreme dippers (4%). But nondippers were significantly less likely to be smokers (17%) than were dippers (25%) or extreme dippers (22%).
During an average of 5 years of follow-up, there were 116 cardiovascular events. The event rate per 100 patient-years was 0.91, 1.93, and 1.73 in dipper, nondipper, and extreme-dipper patients, respectively. Event-free survival was significantly different among the groups, reported Dr. Pierdomenico, professor of medicine and aging science at G. d'Annunzio University in Chieti, Italy.
A Cox regression analysis that adjusted for various covariates, including 24-hour BP and drug therapy, showed that cardiovascular risk was significantly higher in nondipper patients (relative risk 1.7) and in extreme-dipper patients (RR 2.2), compared with dipper patients.
“This and many other studies would argue for 24-hour blood pressure monitoring at least in the subgroup of people at very high risk of being nondippers,” said Dr. George Bakris, director of the hypertension center at the University of Chicago, in a statement, “for example, those with kidney disease [glomerular filtration rate less than 60 mL/min per 1.73 m
The evidence supports 24-hour blood pressure monitoring at least in patients at very high risk of being nondippers. DR. BAKRIS