Blood-Brain Barrier Disruption Before Interhospital Transfer for Thrombectomy and Clinical Outcome

In acute ischemic stroke with large vessel occlusion (AIS-LVO), interhospital transfer for endovascular therapy (EVT) provides an ideal therapeutic window during which neuroprotective strategies could be evaluated, allowing sufficient exposure before reperfusion. We aimed to determine whether blood-brain barrier (BBB) disruption assessed before interhospital transfer for EVT is associated with 24-hour hemorrhagic transformation (HT) and 3-month functional outcome.

In this multicenter retrospective study, we included patients with anterior circulation AIS-LVO transferred from 4 French primary stroke centers (PSCs) to comprehensive stroke centers for EVT assessment, with baseline MR perfusion imaging performed at the PSC before transfer. BBB disruption was quantified as the percentage signal change due to gadolinium leakage on perfusion source images. Mean permeability derangement (MPD) was defined as the average of all voxels within the ischemic core exhibiting permeability values greater than a prespecified threshold. The primary outcome was any intraparenchymal HT on 24-hour follow-up imaging. The association between MPD and HT was studied in multivariable mixed binary logistic regression analyses.

A total of 289 patients were included: the median age was 74 years (interquartile range 63-81), 49% were female, the median NIHSS score was 13 (7-19), the median last-seen-well-to-PSC imaging time was 2.5 hours (1.7-4.7), and the median core volume was 17 mL (0-40). Intravenous thrombolysis was administered before transfer in 71% of patients, and EVT was eventually performed in 71%. The median time from PSC imaging to comprehensive stroke center arrival was 3.3 hours (2.6-3.8). Any HT at 24 hours occurred in 129 patients (45%). In multivariable analysis, MPD ≥3% was independently associated with any HT (OR 6.58; 95% CI 2.84-15.22; p < 0.001) after adjustment for core volume, glucose level, occlusion site, onset-to-imaging time, and whether EVT was performed. Similar associations were observed for parenchymal hematoma (adjusted OR 3.31; 95% CI 1.48-7.41; p = 0.004) and poor 3-month functional outcome (modified Rankin Scale score 3-6, adjusted OR 3.13; 95% CI 1.38-7.09; p = 0.006).

BBB disruption on pretransfer perfusion MRI is associated with 24-hour HT and poor 3-month functional outcome in patients with AIS-LVO. These findings highlight its potential value for early risk stratification and justify prospective evaluation of BBB-targeted strategies during interhospital transfer for EVT.