OS 07-05 DETERMINANTS OF MORNING BLOOD PRESSURE SURGE IN NORMOTENSIVE SUBJECTS AND UNTREATED HYPERTENSIVE PATIENTS: THE KOREAN AMBULATORY BLOOD PRESSURE MULTICENTER OBSERVATIONAL STUDY.

OBJECTIVE: Morning blood pressure (BP) surge has been regarded as a predictor of adverse cardiovascular events. However, its determinants remain controversial and no previous studies have evaluated whether or not there is a difference in the determinants of morning BP surge between normotensive and hypertensive subjects.

DESIGN AND METHOD: We included 476 normotensive subjects (mean age 52.8 ± 15.4 years, 49.2% males) and 1028 untreated hypertensive patients (age 51.7 ± 13.9 years, 56.1% males) from the Korean Ambulatory Blood Pressure Registry. Sleep-trough morning BP surge was defined as the difference between mean systolic BP (SBP) during the 2 hours after awakening and the average of three readings centered on the lowest sleep SBP level.

RESULTS: Hypertensive patients had higher sleep-trough morning BP surge compared to normotensive subjects (27.6 ± 17.8 mmHg vs 25.7 ± 13.7 mmHg, p = 0.023). In multivariate linear regression analysis, 24-hour heart rate (24-h HR) variability (β = 0.397, p < 0.0001) was associated with MS in normotensive subjects. Meanwhile, in hypertensive patients, age (β = -0.113, p = 0.046), diabetes mellitus (β = -0.109, p = 0.043), daytime SBP (β = 0.301, p < 0.0001), night-time SBP (β = -0.375, p < 0.0001), 24-h SBP variability (β = 0.290, p < 0.0001) and night-time diastolic BP (DBP) variability (β = 0.185, p = 0.001) were found to be independent determinants of morning BP surge.

CONCLUSIONS: Morning BP surge was more pronounced in hypertensive patients than in normotensive subjects, and its determinants were also different between them. These findings suggest that different pathogenic mechanism of morning BP surge may exist in normotensive subjects and hypertensive patients, respectively.