Abstract WMP91: Angiographic Predictors Of Balloon Test Occlusion Outcomes

Abstract

Introduction: Balloon test occlusion (BTO) with adjunctive single-photon emission computed tomography (SPECT) has been utilized to predict clinical tolerance after permanent internal carotid artery (ICA) occlusion. Cerebrovascular anatomical characteristics might predict BTO outcomes and identify patients susceptible to test failure. Methods: We performed a single center retrospective study of patients who underwent catheter based cerebral angiogram and ICA BTO from July 2013 to June 2020. SPECT imaging was completed in all the patients who passed the clinical BTO; technetium 99m-ethyl cysteinate dimer was injected intravenously after 15-30 min of occlusion and induced hypotension. The diameter of each of the vessels of the Circle of Willis was measured angiographically. The severity of hypoperfusion on SPECT imaging was classified as none, mild, low intermediate, high intermediate, and severe. Results: A total of 57 patients underwent BTO; neoplasia was the most common indication (n=43, 75%). Twelve patients (21.1%) developed neurologic symptoms and clinically failed the BTO; 45 patients (78.9%) passed and proceeded to SPECT. Contralateral dominant vertebral artery (p=0.02), smaller ACom (p=0.002) and ipsilateral PCom (p=0.03) diameters were correlated with clinical BTO failure. Smaller ACom was most predictive with an AUC of 0.907. The Youden index identified an ACom diameter threshold of 1.1 mm, which demonstrated a sensitivity of 91.7% and specificity of 77.8% (OR 0.026, 95% CI 0.003 - 0.226, ROC=0.847) for the prediction of BTO failure. Patients with severe SPECT asymmetry had significantly smaller caliber ACom arteries (ACom median diameter 0.95 mm vs. rest of cohort median 1.4; p=0.0073). Conclusions: BTO outcomes may be predicted using angiographic findings. A small (<1.1 mm) anterior communicating artery, and, less significantly, a small ipsilateral posterior communicating artery can be used to identify patients who are likely to fail BTO.