A Prospective Evaluation of Clinical Outcomes in Acute Ischemic Stroke After Endovascular Treatment w/Doppler

Overview

Endovascular therapy (EVT) has proven to be more beneficial for patients with AIS caused by large vessel occlusions (LVO) than medical management alone. A recent meta-analysis of 5 RCTs showed that EVT significantly reduced disability at 90 days compared to medical management \[1\]. Despite its obvious benefits, patients may have neurological deterioration despite successful thrombectomy due to ischemia progression, intracranial hemorrhage, re-occlusion, or vasogenic edema. The incidence of early neurological deterioration (END) following EVT for acute stroke has been reported to be ranging from 14.1-35.2% with some studies defining END up to 7 days and some restricting the definition between 6-72 hours post thrombectomy. A small proportion of these patients, approximately 5.9-10.5%, experienced sICH following EVT. Whether END occurs due to ischemic or hemorrhagic it leads to worse outcomes.

One reason for END is impaired cerebral autoregulation (CAR), subsequent to the LVO. Cerebral autoregulation (CAR) is the brain's ability to maintain relatively constant cerebral blood flow (CBF) despite fluctuations in systemic blood pressure. Failure of CAR is associated with secondary brain injury that may occur as an extension of the initial ischemic core with the no-reflow phenomenon in hypoperfusion. CAR may also be impaired causing cerebral edema, or hemorrhagic transformation with cerebral hyperperfusion. The degree of recanalization, preexisting hypertensive profile and post thrombectomy blood pressure can impact CAR and contribute to risk of hypo or hyperperfusion. In the DAWN trial, EVT was performed 6 to 24 hours after stroke onset, and BP was controlled to less than 140/90 mmHg in patients who achieved reperfusion with mTICI 2b or 3. This trial reported incidents of 6% for END and 14% for sICH, respectively. The BEST-II trial, which compared moderate BP control (SBP of either 140 or 160 mmHg) with standard control (SBP less than 180 mmHg) in patients successful post-EVT, suggested a low probability of benefit from lower SBP targets. The incidence of sICH in this trial was 5%. The 2019 American Heart Association/American Stroke Association (AHA/ASA) guidelines recommended a BP goal of 180/105 after EVT, as a reasonable extrapolation from the IVT literature. However, the recommendation for BP control still lacks clear supporting evidence. While the proposed role of CAR in post thrombectomy underscores the need for evaluating CAR in patients after EVT to evaluate patient specific systemic blood pressure parameters bedside measurements of CAR in these patients is still not a practical clinical possibility. Most CAR evaluation devices need ICP that is invasive and typically not amenable in post thrombectomy patients. Non-invasive methods of evaluating CAR based on transfer function analysis are still not validated for widespread clinical use and need significant IT infrastructure. TCD is recognized as a diagnostic tool for measuring CBF. One of its key advantages lies in its ability to perform non-invasive, real-time monitoring directly at the patient's bedside, making it invaluable in acute stroke management. TCD based CBV measurement can provide valuable insights into cerebral hemodynamics and when combined with systemic BP data TCD has the potential to guide critical decisions, such as post-EVT BP management, to prevent secondary injuries like ICH. Tools like TCD, which can provide real-time assessment of cerebral hemodynamics, remain underutilized in this context. We propose this study to evaluate specific TCD parameters in post-EVT patients who develop early neurological deterioration or ICH that can serve as future targets of therapy. Understanding these parameters may provide valuable insights into the hemodynamic changes that occur after EVT and help guide future BP management strategies to reduce the risk of complications like ICH.