Abstract TP73: Lower Prehospital Blood Pressure Is Not Associated with Larger Infarct Volumes in Non-lacunar Ischemic Stroke Patients

Abstract

Background: Although prehospital blood pressure (BP)-lowering trials in acute stroke have begun, concerns persist that hypotension may exacerbate hypoperfusion and increase infarct volumes, particularly in non-lacunar stroke. We tested the hypothesis that lower prehospital BP is associated with larger infarct volumes in non-lacunar ischemic stroke. Methods: We conducted a retrospective study of consecutive patients with suspected stroke transported by Emergency Medical Services (EMS) during an 18-month period. Serial prehospital BP data were obtained from a centralized EMS database. Hospital charts and neuroimaging were reviewed. Stroke etiology was classified using TOAST criteria. Infarct volumes were measured on follow-up MRI or CT using semi-automated thresholding planimetric techniques by two independent raters, blinded to prehospital BP. Results: Of a total 960 patients transported by EMS, 367 had a final diagnosis of ischemic stroke. Stroke etiology was large artery disease in 51 patients, cardioembolic in 140, lacunar in 44, other determined etiology in 22, and cryptogenic in 110 patients. Follow-up imaging was available in 315 patients (163 MR, 152 CT) at a median (IQR) 1(1) days. The overall median non-lacunar infarct volume was 16.5 (49.6) ml, median NIHSS was 7(10), and mean prehospital SBP was 153 ± 25 mmHg. Mean prehospital SBP was lower in patients with other determined etiology (133.2 ± 26.1 mmHg, p<0.01) than cardioembolic (150.9 ± 25.5 mmHg), large artery disease (157.1 ± 26.1 mmHg) and cryptogenic stroke (157.7 ± 22.9 mmHg). Median infarct volume was similar across categories of stroke etiology (large artery disease (16.3 (60.3) ml), cardioembolic (19.9 (76.2) ml), other determined etiology (23.9 (33.6) ml), and cryptogenic stroke (11.5 (35.9) ml), p=0.12). There was no correlation between mean prehospital SBP and mean infarct volume (r =-0.06, p=0.33). NIHSS score was correlated with mean infarct volume (r=0.6, p<0.001), but not mean prehospital SBP (r=-0.07, p=0.24). Conclusion: These data provide no evidence to suggest that lower prehospital BP is associated with larger infarct volumes in patients with non-lacunar ischemic stroke. The effect of BP reduction on infarct volumes should be assessed as part of randomized trials.