PROGNOSTIC VALUE OF AWAKE AND ASLEEP AMBULATORY BLOOD PRESSURE FOR PREDICTION OF CARDIOVASCULAR MORBIDITY: RESULTS OF THE MAPEC STUDY: PP.3.90

Abstract

Objectives: Target organ damage and cardiovascular risk are more closely associated with ambulatory (ABPM) than with clinic blood pressure (BP). Moreover, it has been suggested that nighttime BP is a better predictor of risk than daytime or 24 h BP. All previous trials on the prognostic value of ABPM have relied only on a single baseline profile from each participant, without accounting for changes in BP during follow-up. We have compared to prognostic value of ABPM and clinic BP in the MAPEC study, where participants were systematically evaluated by repeated ABPM. Methods: This prospective study investigated 3344 subjects (1718 men), 52.6 ± 14.5 years of age. At baseline, BP was measured every 20-min from 07:00 to 23:00 h and every 30-min at night for 48 h. Just before starting ABPM, six clinic BP measurements were obtained with a validated oscillometric device. ABPM was scheduled yearly or more frequently (quarterly) if treatment adjustment was required. The Cox proportional-hazard model was used to estimate relative risks of cardiovascular events associated to clinic and ambulatory BP. Results: After a median follow-up time of 5.6 years, ambulatory BP predicted outcome better than clinic BP. Moreover, the asleep BP mean was consistently a stronger predictor than the awake or 24 h BP mean. Based on the baseline ABPM, with adjustment for gender, age, diabetes, antihypertensive treatment, and clinic BP, the relative hazard ratio (HR) for each 10-mmHg increase in systolic BP was 1.18 (1.09–1.28; P < 0.001) for awake mean and 1.29 (1.21–1.37; P < 0.001) for asleep mean. Cardiovascular morbidity was even more strongly associated with systolic asleep BP when data were analyzed on the basis of the ABPM profile closer to the event (1.30, 1.23–1.38, P < 0.001). Conclusions: ABPM is superior to clinic BP in predicting cardiovascular morbidity and mortality. After adjustment for relevant confounding risk factors, the asleep BP mean provides higher prognostic value than awake BP mean. Results further indicate that decreasing asleep BP reduces cardiovascular risk beyond 24h-mean BP lowering.