Background Ambulatory blood pressure (BP) monitoring has long been used to monitor BP in hypertension and lately emerged as a useful tool to detect hypotensive susceptibility in reflex syncope. However, hemodynamic characteristics in reflex syncope have not been sufficiently explored. The present study investigated the differences between ambulatory BP monitoring profiles associated with reflex syncope and normal population. Methods and Results This is an observational study comparing ambulatory BP monitoring data from 50 patients with reflex syncope and 100 controls without syncope, age- and sex-matched 1:2. Mean 24-hour systolic (SBP) and diastolic BP, pulse pressure (24-hour PP), dipping status, and number of daytime SBP drops <90 to 100 mm Hg were analyzed. Variables associated with reflex syncope were investigated using multivariable logistic regression. Patients with reflex syncope displayed significantly lower 24-hour SBP (112.9±12.6 versus 119.3±11.5 mm Hg, P=0.002), higher 24-hour diastolic BP (85.2±9.6 versus 79.1±10.6 mm Hg, P<0.001), and markedly lower 24-hour PP (27.7±7.6 versus 40.3±9.0 mm Hg, P<0.001) compared with controls. Daytime SBP drops <90 mm Hg were more prevalent in patients with syncope (44% versus 17%, P<0.001). Daytime SBP drops <90 mm Hg, 24-hour PP <32 mm Hg, 24-hour SBP ≤110 mm Hg, and 24-hour diastolic BP ≥82 mm Hg were independently associated with reflex syncope, with 24-hour PP <32 mm Hg achieving the highest sensitivity (80%) and specificity (86%). Conclusions Patients with reflex syncope have lower 24-hour SBP but higher 24-hour diastolic BP and more frequent daytime SBP drops <90 mm Hg than individuals without syncope. Our results support the presence of lower SBP and PP in reflex syncope and suggest a role for ambulatory BP monitoring in the diagnostic work-up of this condition.

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