Abstract 155: No Increased Stroke Risk with Lower Blood Pressures in Hemodynamic Cerebral Ischemia

Abstract

Patients with symptomatic carotid artery occlusion and hemodynamic cerebral ischemia manifested by increased oxygen extraction fraction (OEF) are at 20-25% risk for ipsilateral stroke within 2 years. Disagreement exists whether strict blood pressure control is the best medical management for these patients or if higher blood pressures are needed to preserve cerebral perfusion. To address this issue, we analyzed data from the non-surgical group of the Carotid Occlusion Surgery Study (COSS), a randomized, controlled trial performed to determine whether EC-IC bypass could reduce subsequent ipsilateral ischemic stroke at two years in participants with recently symptomatic internal carotid artery occlusion and increased OEF. Of the 98 patients in the non-surgical group, 95 had 1-19 blood pressures recorded at follow-up visits. Average systolic and diastolic blood pressures were calculated from these data. Cox regression analyses were used to estimate the relative hazard of a post-randomization ipsilateral stroke in the tercile of subjects with the lowest average blood pressures ( </= 124 mm Hg systolic or 73 mm Hg diastolic) compared to the remainder. Lower blood pressures were associated with reduced, not increased, stroke risk. If the samples analyzed were from populations in which the true hazards were the same, hazard ratios of this magnitude or less would be expected less than 10% of the time. We cannot conclude from these data that strict blood pressure control is beneficial in patients with symptomatic carotid occlusion and increased OEF. However, since we found no evidence that that blood pressures below 124/73 were associated with increased stroke risk, we recommend treatment of blood pressure in these patients according to JNC VII guidelines to targets of < 140/90 or <130/80 for those with concomitant diabetes mellitus or kidney disease.