Blood Pressure Variability Is Associated with Infarct Growth in Acute Ischaemic Stroke

Abstract

Introduction: Evidence-based blood pressure (BP) targets in acute ischaemic stroke are lacking. Previous observational studies have focused on single baseline BP and clinical outcomes, without consideration for dynamic changes. We aim to determine the association between BP parameters including variability, peak, nadir, median and mean during stroke and infarct growth (primary outcome), risk of haemorrhagic transformation, and functional outcome (secondary outcomes). Methods: Suspected stroke patients were prospectively recruited from a single comprehensive stroke centre. Multimodal computed tomography imaging was used to define infarct core. BP was recorded as per national stroke guidelines during the initial 24 h. Infarct growth and evidence of parenchymal haemorrhage were determined by follow-up magnetic resonance imaging at 24 h. Functional outcome at 3 months was assessed using the modified Rankin Scale. Subgroup analysis was performed according to stroke aetiology and treatment for the association between BP, infarct volume growth, and risk of haemorrhagic transformation. The association between BP parameters and outcomes were determined using regression modelling. Results: A total of 229 patients were included in this study. The median age was 67.4, 64.4% were male, and the baseline National Institutes of Health Stroke Scale was 8. BP variability (BPV) was independently associated with increased infarct growth (multivariate coefficient 1.60, 95% CI: 0.27–2.94, p = 0.19) and an increased odds of parenchymal haemorrhage (adjusted OR 1.21, 95% CI: 1.02–1.44, p = 0.028). The odds of a favourable outcome at 90 days were inversely associated with BPV on simple, but not adjusted logistic regression. On subgroup analysis, only in patients with large vessel occlusions, undergoing endovascular clot retrieval, was BPV associated with infarct growth (multivariate-adjusted coefficient 2.62, 95% CI: 0.53–4.70, p = 0.014) and an increased odds of haemorrhagic transformation (adjusted OR 1.26, 95% CI: 1.01–1.57, p = 0.045). Conclusion: An increase in BPV was associated with infarct expansion, increased risk of haemorrhagic transformation and was negatively associated with favourable functional outcomes at 3 months.