The blood pressure paradox in acute ischemic stroke

Objective To explore the association of poststroke baseline blood pressure with cerebral collateral flow and functional outcome in acute ischemic patients with large vessel occlusion/stenosis. Methods Patients identified with large vessel occlusion/stenosis with baseline multimodal computed tomography, follow-up imaging, and complete clinical profiles were included. A 90-day modified Rankin Scale of 0-1 was defined as an excellent functional outcome. Cerebral collateral flow was quantified by the volume ratio of tissue within the delay time >3 seconds perfusion lesion with severely delayed contrast transit (delay time >3 seconds/delay time >6 seconds). Results There were 306 patients included in this study. With every increase of 10 mmHg in baseline systolic blood pressure, the odds of achieving an excellent functional outcome decreased by 12% in multivariate analysis (odds ratio = 0.88, p = 0.048). Conversely, increased baseline blood pressure was associated with better collateral flow. In subgroup analysis of patients with major reperfusion, higher blood pressure was associated with decreased infarct growth and a better clinical outcome, and vice versa in patients without reperfusion. Interpretation Higher baseline blood pressure in acute ischemic stroke patients with large vessel occlusion/stenosis was associated with better collateral flow. However, for patients without reperfusion, higher baseline blood pressure was associated with increased infarct growth, leading to an unfavorable clinical outcome. The relationship between blood pressure and outcomes is highly dependent on reperfusion, and active blood pressure-lowering treatment may be inappropriate in acute ischemic stroke patients prior to reperfusion treatment. ANN NEUROL 2019;85:331-339.