Hypoperfusion intensity ratio as a predictor of outcomes after thrombectomy triage: A call for data homogeneity

Background: Collateral blood flow markers have been associated with outcomes after thrombectomy in patients presenting with acute ischemic stroke due to large vessel occlusion (AIS-LVO). Hypoperfusion intensity ratio (HIR), a metric reflecting tissue level collaterals, is one such marker with the potential to delineate patients who do and do not do well after thrombectomy. We determined if HIR correlated with successful reperfusion after thrombectomy. Methods: Using Nested Knowledge, we screened literature for studies comparing patients with favorable versus unfavorable HIR, distinguished by a cutoff of 0.4, who underwent thrombectomy triage. The primary outcome was reperfusion success, as measured by thrombolysis in cerebral infarction ≥2b and secondary outcomes included rate of symptomatic intracranial hemorrhage, mortality at 90 days, and modified Rankin scale scores 0–2 at 90 days. A random effects model was used to compute pooled prevalence rates and their corresponding 95% confidence intervals (CI). Results: Three studies with 973 patients, 496 with favorable HIR, and 477 with unfavorable HIR were included in this meta-analysis. The odds of reperfusion success were not significantly different between patients who had favorable versus unfavorable HIR (OR 0.96, 95% CI: 0.31–3.04) across two of the studies. Analysis of the remaining outcome variables was precluded by significant heterogeneity in data element reporting. Conclusions: This meta-analysis was considerably limited by heterogeneity. Future meta-analyses on this topic, and other topics in the field of neurointervention would benefit from improved harmonization of study design and data element reporting.