The significance of blood pressure variability for the development of hemorrhagic transformation in acute ischemic stroke

Background and Purpose: Elevated blood pressure (BP) is commonly observed in acute ischemic stroke and is known to be associated with hemorrhagic transformation (HT). However, the effect of BP variability on the development of HT is not known well. Methods: A consecutive series of patients with acute ischemic stroke, who were hospitalized within 24 hours of onset and showed no HT on initial gradient echo MRI, were enrolled in this study. BP measurements during the first 72 hours were obtained, and BP variability of each patient was described using various summary parameters: SD, maximum (max), minimum (min), difference between max and min (max-min), average squared difference between successive measurements (sv), and maximum sv (svmax). Results: Of 792 patients meeting the eligibility criteria, 70 (8.8%) developed HT. Among BP variability parameters categorized into quartiles, SBP_max, SBP_min, SBP_max-min, SBPsv_max, DBPSD, DBP_max, DBP _min, DBP_max-min, and DBP_svmax were significantly associated with HT independent of mean SBP, age, interval from onset to arrival, initial stroke severity, diabetes mellitus, stroke subtype, thrombolysis, initial glucose, and total cholesterol (P<0.05 on likelihood ratio test of trend). The analyses about the interaction between thrombolysis and variability parameters showed that the effects of BP variability on the development of HT did not differ by whether patients received thrombolysis or not. Conclusions: Our study suggests that we may consider not only the absolute level of BP but also its variability to prevent hemorrhagic transformation.