Abstract WP289: Insufficient Low-Frequency Blood Pressure Activity Under Orthostatic Stress Predicts Blunted Night-to-Day Blood Pressure Dipping in Patients With Ischemic Cerebrovascular Disease

Introduction: Blunted night-to-day blood pressure (BP) dipping was common in ischemic cerebrovascular disease (ICVD). BP dipping could be influenced by baroreflex, which stabilized BP by regulating sympathovagal balance. We sought to determine the relationship between baroreflex function and BP dipping in patients with ICVD.

Methods: Patients with ICVD stable for at least 3 days were enrolled. Beat-to-beat BP and ECG were monitored in 3 phases of active standing [supine (S), supine to upright (SU), upright (U), 4 min each]. Baroreflex function was evaluated by time-domain and frequency-domain baroreflex sensitivity (BRS) and by indices of sympathovagal balance [low (0.04-0.15 Hz) to high (0.15-0.4 Hz) frequency ratio (LHR) of systolic BP (SBP) and RR interval (RRI)]. BP dipping was measured as percentage with 24h ambulatory BP monitoring. SBP dipping <0 was defined as reverse BP dipping.

Results: Among 66 patients, mean SBP dipping was 3.54% ± 6.85%. SBP dipping was positively related to BP-LHR _SU (Spearman r=0.258, p=0.036), but had no significant correlation with time-domain and frequency-domain BRS, LHR _S and LHR _U of BP and RRI, or RRI-LHR _SU (Table 1). Lower log BP-LHR _SU was indicative of less SBP dipping [β (95% CI): 6.53 (1.67-11.40), p=0.009] and the presence of reverse BP dipping [OR (95% CI): 0.11 (0.02-0.65), p=0.015], even after adjusting age, sex, vascular risk factors, 24h mean BP level, NIHSS and mRS scores (Table 2).

Conclusions: Low BP-LHR _SU , which suggested sympathetic underactivation of BP activity during the orthostasis-stimulated baroreflex engagement, might be a pathophysiological link between baroreflex impairment and blunted BP dipping in ICVD.