Transcranial doppler (TCD) in predicting outcomes following successful mechanical thrombectomy of large vessel occlusions in anterior circulation: a systematic review and meta-analysis

BACKGROUND: Transcranial Doppler (TCD) is a non-invasive, bedside tool that allows for real-time monitoring of the patient's hemodynamic status following mechanical thrombectomy (MT). This systematic review and meta-analysis aims to evaluate the predictive value of TCD parameters following successful MT (Thrombolysis in Cerebral Infarction 2b-3). METHODS: In July 2024, we searched PubMed, Embase, and Scopus, to identify observational studies in which TCD parameters were measured within 48 hours of MT. Using random-effects models, we compared four TCD parameters (mean flow velocity (MFV), MFV index, pulsatility index (PI), and peak systolic velocity (PSV) among groups with vs without hemorrhagic transformation (HT) and favorable vs poor functional recovery (modified Rankin Scale 0-2 vs 3-6). RESULTS: Eleven studies comprising 1432 patients (59% male; mean age range: 63-73 years) were included. The MFV and MFV index were higher in patients with HT (Hedges' g=0.42 and 0.54, P=0.015 and 0.005, respectively). Patients with MFV index ≥1.3 showed a higher risk of all HT (RR 1.97; 95% confidence interval (CI) 1.28 to 3.03, P=0.002), symptomatic HT (RR 4.68; 95% CI 1.49 to 14.65, P=0.008), and poor functional status at 90 days (RR 1.65; 95% CI 1.27 to 2.14, P=0.029), respectively. There was no difference in mean PSV (P=0.1) and PI (P=0.3) among groups with and without HT. CONCLUSION: This study underscores the prognostic value of the MFV index in predicting HT, symptomatic HT, and poor functional recovery after successful MT in the anterior circulation. Large-scale, multi-center studies are necessary to confirm these findings and to validate the MFV index as a reliable predictor for improving post-thrombectomy care.