Transcranial Doppler Evaluation After Endovascular Thrombectomy for Acute Ischemic Stroke (PRECISE-TCD)

PRECISE-TCD is a single-center, prospective, observational study designed to evaluate the association between transcranial Doppler (TCD)-derived cerebral hemodynamic parameters and neurological outcomes in patients with acute ischemic stroke (AIS) after endovascular thrombectomy (EVT). The study will be conducted at Virginia Commonwealth University (VCU) Medical Center in Richmond, Virginia. The study has received IRB approval at VCU under protocol HM20032561 and will be conducted in accordance with the Declaration of Helsinki and institutional regulatory requirements.

Eligible participants are adults aged 18 years or older with anterior circulation large vessel occlusion (LVO), including anterior cerebral artery (ACA), middle cerebral artery (MCA), or internal carotid artery (ICA) stroke, treated with EVT, including tandem occlusions. Participants must also have an adequate acoustic window detectable by TCD. Patients will be excluded if they have inadequate acoustic windows defined as lack of bilateral MCA signal at standard depths, are pregnant, or are incarcerated. Informed consent will be obtained from the participant or a legally authorized representative using the IRB-approved REDCap e-Consent process.

TCD examinations will be performed as soon as possible after EVT, daily for 72 hours, and when possible, close to any reported neurological deterioration or head CT obtained within 72 hours after EVT. All TCD examinations will be performed by trained personnel using low-frequency TCD probes. Vessels assessed will include the bilateral MCA, ACA, posterior cerebral artery (PCA), carotid siphon, vertebrobasilar arteries, and ophthalmic artery. TCD parameters collected will include peak systolic velocity (PSV), end-diastolic velocity (EDV), mean flow velocity (MFV), and pulsatility index (PI). Sampling volume will be 5-10 mm, and insonation depths will be adjusted by vessel according to the standardized acquisition protocol. Time-averaged mean flow velocity (TAMMV) and PI will be automatically derived from preset values. All waveforms will be stored digitally and reviewed when needed to ensure adherence to protocol and consistency of measurements.

Collateralization status will be assessed using established TCD criteria, including reversal of flow in the ipsilateral ACA, high-velocity flow patterns in the ipsilateral ACA or PCA with stenosis ruled out on prior CTA or DSA, and reversal of the ipsilateral ophthalmic artery. Serial monitoring is designed to capture the early post-reperfusion period when cerebral hemodynamic instability, autoregulatory dysfunction, hyperperfusion, hypoperfusion, and collateral flow changes may occur.

The primary outcome is the association between TCD-derived hemodynamic parameters and early neurological deterioration (END) within 72 hours after EVT. END is defined as any of the following: an increase in total NIHSS score of 4 points or more; an increase in NIHSS subcategory 1a score of 1 point or more; intracranial hemorrhage within 72 hours of EVT on CT or MRI classified using the Heidelberg Classification; or any neurological examination change prompting emergent head CT at clinician discretion within 72 hours post-thrombectomy. Secondary outcomes include post-EVT NIHSS score at 24 hours and at discharge, discharge disposition, and phone-based modified Rankin Scale (mRS) at 90 days. Additional neurological outcomes of interest include intracranial hemorrhage and symptomatic intracranial hemorrhage.

The anticipated enrollment is up to 300 participants. This sample size is based on the expected incidence of END after EVT and the need to detect clinically meaningful associations between TCD-derived hemodynamic profiles and END. An interim descriptive analysis will be performed after approximately 50% of the planned cohort is enrolled to assess the observed incidence of END and the completeness and quality of serial TCD data acquisition.

Continuous variables will be summarized as mean with standard deviation or median with interquartile range, and categorical variables as counts and percentages. Baseline characteristics will be compared between participants with and without END. TCD-derived parameters will be analyzed at both vessel and patient levels, including bilateral vessel measurements, ipsilateral-to-contralateral velocity ratios, inter-vessel velocity relationships, hemispheric asymmetry indices, and collateralization patterns. Joint models for longitudinal and time-to-event data will be used to explore the association between changes in TCD parameters and time to END. Unsupervised clustering methods will be applied to standardized TCD features, including vessel velocities, pulsatility indices, hemispheric asymmetry measures, collateral flow indicators, and temporal trajectory patterns, to identify integrated cerebral hemodynamic phenotypes. Secondary analyses will evaluate associations between early TCD-derived hemodynamic patterns and functional outcomes including NIHSS at 24 hours and discharge, discharge disposition, and 90-day mRS.

TCD ultrasound provides a validated, noninvasive bedside method for real-time assessment of cerebral blood flow velocities after endovascular thrombectomy. Prior studies have demonstrated that elevated post-reperfusion middle cerebral artery velocities, specifically peak systolic velocity ≥118 cm/s or a mean flow velocity index ≥1.12, are independently associated with intracranial hemorrhage and vasogenic edema following successful recanalization. Impaired dynamic cerebral autoregulation measured by TCD within the first 24 hours after EVT independently predicts unfavorable functional outcomes at 90 days. Prospective studies have further demonstrated that TCD-guided blood pressure management after EVT is associated with improved functional outcomes compared with standard care. Despite this evidence, comprehensive multiparameter TCD assessment integrating collateral circulation, hemispheric asymmetry, and serial hemodynamic trajectories has not been evaluated in U.S. stroke populations, and validated physiologic thresholds to guide individualized post-EVT management remain undefined. PRECISE-TCD is designed to address these gaps.