Abstract 3688: Factors Associated with Individual Variations in Systolic Blood Pressure Responsive to Intravenous Antihypertensive Medication. Results from the Antihypertensive Treatment of Acute Cerebral Hemorrhage (ATACH) Study

Abstract

Introduction: There is considerable variation in blood pressure response to intravenous antihypertensive medication within patients with intracerebral hemorrhage (ICH). Objective: To study the variation in systolic blood pressure (SBP) responsiveness to IV nicardipine infusion and effect of various baseline factors on such responsiveness. We also studied the effect of SBP responsiveness on hematoma expansion, perihematomal edema, and three month outcome among subjects with ICH. Material and Methods: A post-hoc analysis of a multicenter prospective study recruiting subjects with ICH and elevated systolic blood pressure (SBP)≥170 mm Hg who presented within 6 hours of symptom onset was performed. Baseline SBP was calculated using the average of maximum and minimum SBP recorded prior to initiation of treatment. The SBP responsiveness was defined by the ratio between maximum change in SBP (difference between initial SBP and minimum SBP within the first hour) and maximum dose of nicardipine used in the first hour. This value was dichotomized at the median of 8.0, and we defined those with higher values to be responders and lower to be non-responders. We evaluated the effect of SBP reduction (relative to initial SBP) on: (1) hematoma expansion, defined as an increase in the volume of intraparenchymal hemorrhage of >33% measured on the 24-hour computed tomographic (CT) scan compared with the baseline CT scan; (2) relative edema expansion, defined as increase of >40% in edema volume to hematoma volume ratio between baseline and 24-hour CT scan; and (3) poor outcome defined by modified Rankin scale (mRS) of 4-6 at 3 months following treatment. Results: A total of 56 subjects were treated with IV nicardipine (aged 62 ±15 years; 57% men). The initial mean serum glucose was higher, although not statistically significant, among the 29 responders compared with 27 poor responders (148±72 versus 125±41). There were no clinically meaningful differences in the patient’s age, initial hematoma volume, initial Glasgow Coma Scale score, serum creatinine, or previous use of antihypertensive medication between responders and poor responders. The mean maximum dose of IV nicardipine used was 6.9 (±4.2) mg/hr and mean maximum reduction of SBP of 55.4 (±32.0) mm Hg within the first hour. The risk of poor outcome (mRS 4-6) in the responder was 10% less relative to the non-responders (relative risk [RR]=0.90, 95% confidence interval [CI]: 0.48, 1.69; n=50). The RRs were 0.81 (95% CI: 0.34, 1.93; n=54) for hematoma expansion >33%; and 0.89 (95% CI: 0.52, 1.53; n=51) for relative edema expansion >40%. Conclusions: There is considerable variation in blood pressure responsiveness to intravenous antihypertensive medication with potential prognostic implications. The variation in responsiveness does not appear to be influenced by other patient related factors that are known to influence functional outcome from ICH.