The blood pressure paradox in acute ischemic stroke

Abstract

on behalf of the INSPIRE Study GroupObjective: 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, followup 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.

A 10% blood pressure drop from baseline during mechanical thrombectomy for stroke is strongly associated with worse neurological outcomes

“…Such an elevated BP, although often described as a risk factor for symptomatic intracranial hemorrhage, worse outcomes and mortality, may also be considered as a marker of stroke severity as well and serve as a compensatory mechanism to maintain cerebral blood flow. Recently, this so-called ‘BP paradox’ was nicely highlighted in AIS patients with an anterior LVO, with better collateral flow and functional outcomes for patients presenting with higher baseline BP in the case of reperfusion 24. Therefore, even a slight BP drop before recanalization may be harmful in such patients for whom cerebral blood flow is highly dependent on cerebral perfusion pressure 25…”

Pre-endovascular therapy change in blood pressure is associated with outcomes in patients with stroke

“…Since any increase in BP in this study was likely spontaneous and not induced, we posit that it was merely a marker of higher infarct volume or worsening ischaemia leading to worse outcomes 5. On the contrary, a decrease in BP prior to recanalisation may have been induced or spontaneous.…”

Diagnosis and management of acute ischaemic stroke

“…However, the BP threshold is based on the original alteplase trial inclusion criteria 52 and there is no evidence that reducing BP in this context helps clinically; indeed, recent data suggest a complex interaction between reperfusion status, BP and patient outcome, with one study suggesting that lowering BP before reperfusion treatment may be inappropriate. 53 …”