Abstract
Introduction:
Blood pressure (BP) reduction in acute ischemic stroke patients can potentially decrease cerebral blood flow (CBF) in ischemic tissue due to disrupted autoregulation, particularly in the ischemic core. We tested this hypothesis using a 3 group non-randomized controlled study of serial CBF measurements in ischemic stroke patients.
Methods:
Patients with acute ischemic stroke ≤72h of symptom onset were recruited. Groups were assigned according to baseline mean arterial blood pressure (MAP): patients with MAP >120mmHg were treated with intravenous labetalol and sublingual (SL) nitroglycerin and those with MAP 100-120 mmHg were treated with SL nitroglycerin. The BP reduction target was 10% of the baseline MAP. Patients with MAP<100 mmHg formed the control group. Patients underwent MR perfusion-weighted imaging (PWI) and diffusion-weighted imaging (DWI) before and after BP reduction. Blinded planimetric assessment was done to determine PWI deficits and DWI lesion volumes in the ischemic core region.
Results:
A total of 48 patients with mean±SD age of 65.4±13.2 years were enrolled at 23.4±15.3h after symptom onset. The mean time difference between perfusion scans was 25.6±9.5 min.Median(IQR) DWI volume was 11.1 (96.8) ml. Mean MAP was 126±7.5 mmHg in the MAP>120 group(n=13), 109.9±4.9 mmHg in the MAP 100-120 group (n=16), and 89.9±6.2 mmHg in the controls (n=19). Mean BP reduction in the treated patients was 11.9±6.7 mmHg (95% CI 15.6-3; p=0.04). Baseline mean relative CBF (rCBF) in ischemic core tissue was 1.1±0.47 in the MAP >120 group, 0.87±0.35 in the MAP 100-120 group and 0.78±0.32 in controls. The mean change in rCBF following BP reduction did not differ between the MAP >120 group (0.03±0.17), MAP 100-120 group (0.06±0.17) and controls (0.08±0.25) (p=0.28). Similarly, there was no difference in the mean relative cerebral blood volume (p=0.3) and relative mean transit time (p=0.58) before and after BP reduction. In patients treated with SL nitroglycerin (n=17), there was no improvement in mean lesional rCBF (0.04±0.17 vs.-0.02±0.18, p=0.25).
Conclusion:
Modest BP reduction does not lead to an immediate decrease in CBF, within the ischemic core. Acute antihypertensive therapy may be less directly harmful than has been postulated.