Predictors of Very Poor Outcome after Mechanical Thrombectomy for Acute Basilar Artery Occlusion

Prognosis for patients with acute basilar artery occlusion (BAO) remains poor. Successful revascularization is a main predictor of favorable clinical outcomes after mechanical thrombectomy for BAO. However, even if mechanical thrombectomy is successful, some patients have a poor clinical outcome, including vegetative state and mortality. This study investigated the factors that are predictive of extremely poor clinical outcomes despite successful revascularization after mechanical thrombectomy for BAO. We evaluated 35 consecutive patients who presented with acute ischemic stroke due to BAO and who were successfully treated with mechanical thrombectomy. A very poor outcome was defined as a modified Rankin Scale (mRS) score of 5 or 6 at 3 months after treatment. The associations between the clinical, imaging, procedural factors, and poor outcome were evaluated. Using univariate analyses, there were significant differences in the preoperative National Institute of Health Stroke Scale (NIHSS) score (22.0 +/- 9.0 vs. 30.5 +/- 4.3, p<0.001), and infarct volume in brain stem (0.11 +/- 0.19 cc vs. 2.55 +/- 1.56 cc, p<0.001) between the control and very poor outcome groups. In receiver operating characteristic (ROC) curve analysis, the area under ROC curve of infarct volume in brain stem was 0.891 to predict very poor outcome. Preoperative infarct volume in brain stem is strong predictor for very poor outcome. The infarct volume in brain stem is useful for deciding treatment indications.