FRET score: predictors of futile recanalisation following endovascular thrombectomy-a multicentre cohort study from the EVATRISP collaboration

Introduction: Endovascular thrombectomy (EVT) is the treatment of choice for LVO stroke, yet nearly half of successfully recanalised patients fail to achieve functional independence, a phenomenon termed futile recanalisation (FR). Predictors of FR remain poorly defined in large, heterogeneous populations. Therefore, we aimed to develop a predictive score for FR. Patients and methods: Endovascular thrombectomy-treated LVO patients from the prospective, multicentre EVATRISP collaboration were included. All patients had known pre-stroke functional status, modified thrombolysis in cerebral infarction (mTICI) score and 90-day mRS. Futile recanalisation was defined as mRS > 2 at 90 days despite mTICI ≥ 2b. Patients with FR were compared to those with successful recanalisation and mRS ≤ 2. The cohort was randomly split into derivation (70%) and validation (30%) sets. Multivariable logistic regression identified independent predictors that were used to construct the futile recanalisation following endovascular thrombectomy (FRET) score. Results: Of 9909 patients, 7272 (73%) achieved successful recanalisation and 3420 (47%) of them experienced FR. In the derivation set, FR was independently associated with older age, diabetes, ischaemic heart disease, higher NIHSS, anterior cerebral artery occlusion, seizures at presentation, non-use of intravenous thrombolysis and lower Alberta Stroke Program Early CT Score (ASPECTS) or posterior circulation ASPECTS. Futile recanalisation patients had longer hospital stays and higher mortality rates. The FRET score demonstrated good discrimination (area under the curve [AUC] 0.721; 95% CI, 0.702-0.740), with FRET ≥ 3 indicating high risk. The validation cohort yielded similar performance (AUC 0.708; 95% CI, 0.680-0.737). Conclusion: The FRET score enables early identification of EVT patients at high risk for FR.