Abstract 2743: Sleep Blood Pressure Variability in Non-dippers of Nocturnal Blood Pressure: An Independent Predictor of Stroke Prognosis in Elderly Hypertension
Objective: Non-dippers of nocturnal blood pressure are independently associated with cardiovascular disease independently of 24-hr BP level. The impacts of blood pressure (BP) variability increased in elderly hypertensives may have different impact on cardiovascular prognosis between awake and sleep periods in non-dippers.
Methods: We performed ambulatory BP monitoring in 811 elderly hypertensive subjects, and followed their stroke prognosis for an average of 41 months. Ambulatory BP variability was calculated as standard deviation (SD) of SBPs separately during awake and sleep periods. The study subjects were classified into the 2 groups: dippers (nocturnal systolic BP [SBP] reduction ≥10%) and non-dippers (nocturnal SBP reduction <10%). Hazard ratio of stroke event was assessed by Cox regression model.
Results: There were 59 stroke events during the follow-up period. Non-dippers had higher stroke incidence than dippers (10% vs 5.7%, p=0.018). In non-dippers, sleep SBP variability (SD of sleep SBPs) was a significant predictor of stroke events (Hazard ratio [HR] of 1 mmHg increase =1.07, p=0.04), independently of 24-hr SBP level and awake BP variability (SD of awake SBPs). In dippers, awake SBP variability (SD of awake SBPs) was a significant predictor for stroke events (HR of 1 mmHg increase =1.10, p<0.001), independently of 24-hr SBP level and sleep SBS variability (SD of sleep SBPs). Morning BP surge was significantly correlated with awake BP variability (r=0.23, p<0.001) and sleep BP variability (r=0.35, p<0.001). When the morning BP surge into the Cox model, the positive association of stroke risk with sleep SBP variability in non-dippers (p=0.04) and awake SBP variability in dippers (p=0.005) remained significant.
Conclusion: Sleep BP variability in non-dippers and awake BP variability in dippers were both significant predictors of stroke risk independently of 24-hr blood pressure and morning BP surge in elderly hypertensive patients.