Hypoperfusion on Early MRI Despite Successful Thrombectomy: A Prospective Imaging and Inflammatory Biomarkers Study

Persistent hypoperfusion despite successful endovascular treatment (EVT) for acute ischemic stroke (AIS) due to large-vessel occlusion is increasingly recognized as associated with poor outcome. It may result from residual distal macrovascular occlusion or microvascular dysfunction (no-reflow). We aimed to characterize early post-EVT hypoperfusion on magnetic resonance imaging and assessed its relationship with a panel of inflammatory biomarkers.

We performed a single-center prospective cohort study at Montpellier Hospital (France, August 2023-November 2024). We included patients with large-vessel occlusion-related acute ischemic stroke and successful (modified Thrombolysis in Cerebral Infarction [mTICI] ≥2b) recanalization who underwent magnetic resonance imaging perfusion as early as feasible after EVT and blood sampling before, during, immediately after, and 24 hours after EVT. Hypoperfusion within the affected vascular territory was assessed using 3 complementary approaches: (1) significant macrovascular hypoperfusion (time-to-maximum >6 s) in any location; (2) wedge-shaped perfusion deficits on time-to-maximum maps, indicative of distal emboli; and (3) visual microvascular hypoperfusion within the infarct core on cerebral blood volume or flow maps (2-rater assessment). Associations between macrovascular hypoperfusion and levels of 37 inflammatory biomarkers, measured using multiplex immunoassays, were analyzed cross-sectionally at each time point, using Mann-Whitney U tests with false discovery rate correction.

Seventy-one patients were included. Median time from recanalization to magnetic resonance imaging perfusion was 45 (19-118) minutes. Time-to-maximum>6 s hypoperfusions were found in 21% of all patients; percentages decreased with better mTICI grades: 45%, 13% and 0% in mTICI 2b, 2c, and 3, respectively. Wedge-shaped hypoperfusion deficits were observed in 97% of mTICI2b, 44% of mTICI2c, and 8% mTICI3 cases. Microvascular hypoperfusion was rare (6%). Several inflammatory markers showed uncorrected associations with time-to-maximum >6 s hypoperfusion, but none survived false discovery rate correction.

Early perfusion deficits after EVT most often reflect residual distal emboli. Macrovascular hypoperfusion was not associated with inflammatory biomarkers. Nevertheless, our integrated imaging and biomarker strategy lays the foundation for future mechanistic and therapeutic studies targeting microvascular reperfusion failure.