Endovascular thrombectomy in addition to intravenous thrombolysis versus intravenous thrombolysis alone in medium distal vessel occlusions: Results from the SITS International Stroke Treatment Register.

BACKGROUND

Endovascular thrombectomy (EVT) is the standard of care for large-vessel occlusion stroke. Medium distal vessel occlusions (MDVO) account for 25-40% of acute ischemic stroke cases, but recanalization rates with intravenous thrombolysis (IVT) are often less than 50%. Recent randomized trials have failed to show better outcomes after EVT versus best medical management in MDVO stroke. The main research question of the study: Is the addition of EVT to IVT associated with benefits or harm when treating patients with MDVO stroke?

METHODS

We performed a retrospective observational study of patients in the Safe Implementation of Treatments of Stroke International Stroke Treatment Registry (SITS-ISTR) 2016-2023, treated with IVT or IVT + EVT for occlusion of the anterior cerebral artery (ACA), posterior cerebral artery (PCA) or distal middle cerebral artery (MCA; M3 and more distal). Only patients with available occlusion data from computed tomographic angiography (CTA) or magnetic resonance angiography (MRA) were included. Patients with M2 occlusions or those treated with EVT only were excluded. Outcomes were acute post-treatment hemorrhage, 3-month modified Rankin Scale (mRS) score, and death at 3 months. Propensity score matching was performed due to baseline imbalances (age, National Institutes of Health Stroke Scale [NIHSS], and occlusion site).

RESULTS

Of 2198 included patients, 295 (13%) were treated with IVT + EVT, and 1903 (87%) received IVT alone. IVT + EVT patients were younger (73 vs. 75) and had higher median NIHSS: 10 (interquartile range [IQR]: 6-15) versus 8 (5-12), p < 0.001. More IVT + EVT patients were functionally independent (mRS 0-1) before stroke at 91.8% versus 83.0% (p < 0.001). For the IVT + EVT group, PCA occlusion was the most common (n = 179, 60.7%), and distal MCA (n = 1140, 59.9%) in the IVT group. After propensity score matching, IVT + EVT was associated with worse 3-month outcomes compared to IVT alone: mRS 0-1 (35.8% vs. 47.0%, p = 0.016, mRS 0-2 52.4% vs. 63.4%, p = 0.017, and death 21.4% vs. 11.8%, p = 0.005). Symptomatic intracerebral hemorrhage rates were higher in the IVT + EVT group according to European Collaborative Stroke Study II (ECASS II): 6.5% versus 2.4%, p = 0.043, but were similar according to National Institute of Neurological Disorders and Stroke (NINDS): 8.2% versus 4.2%, p = 0.095, and Safe Implementation of Thrombolysis in Stroke Monitoring Study (SITS-MOST): 0.6% versus 1.2%, p = 0.825.

CONCLUSIONS

IVT + EVT for MDVO was associated with worse functional outcomes compared to IVT alone. Our results support recent publications but should be interpreted with caution due to the retrospective observational design, warranting further RCTs.