Predictors of good clinical outcomes, mortality, and successful revascularization in patients with acute ischemic stroke undergoing thrombectomy: pooled analysis of the Mechanical Embolus Removal in Cerebral Ischemia (MERCI) and Multi MERCI Trials

Abstract

Background and purpose: The Mechanical Embolus Removal in Cerebral Ischemia (MERCI) and Multi MERCI trials evaluated the safety and efficacy of thrombectomy in the treatment of intracranial arterial occlusions within 8 hours of symptom onset. We sought to determine the predictors of clinical and angiographic outcomes in these patients.

Methods: The trial cohorts were combined in a data set of 305 patients. Twenty-eight baseline variables were included in univariate and multivariate analyses to define the independent predictors of good outcomes (modified Rankin Scale score </=2), mortality, and successful revascularization (Thrombolysis In Myocardial Ischemia 2 to 3 flow).

Results: In the univariate analysis, final revascularization, baseline National Institutes of Health Stroke Scale, age, and systolic blood pressure were associated with both good outcomes and mortality at 90 days (P<0.0018 for all). In the multivariate analysis, final revascularization (OR, 20.4; 95% CI, 7.7 to 53.9; P<0.0001), baseline National Institutes of Health Stroke Scale (OR, 0.86; 95% CI, 0.81 to 0.92; P<0.0001), and age (OR, 0.96; 95% CI, 0.95 to 0.98; P=0.0004) were independent predictors of good outcome. Final revascularization (OR, 0.28; 95% CI, 0.16 to 0.50; P<0.0001), baseline National Institutes of Health Stroke Scale score (odds ratio, 1.09; 95% CI, 1.04 to 1.14; P=0.0001), age (OR, 1.05; 95% CI, 1.03 to 1.07; P<0.0001), and internal carotid artery occlusion (OR, 2.17; 95% CI, 1.22 to 3.86; P=0.0084) were the strongest predictors of mortality. Systolic blood pressure (<150 versus >or=150 mm Hg; OR, 0.42; 95% CI, 0.26 to 0.70; P=0.0007) and M2 occlusion (OR, 3.86; 95% CI, 1.28 to 11.67; P=0.0168) were independent predictors of revascularization.

Conclusions: Final recanalization status represents the strongest predictor of clinical outcomes in patients undergoing thrombectomy. The ability to remove the clot is negatively influenced by systolic blood pressure on presentation perhaps because of the hydraulic forces imposed by higher blood pressures. Although internal carotid artery occlusions are associated with increased mortality, they do not appear to influence the chances of good outcomes. This finding supports the inclusion of internal carotid artery occlusions in future efficacy trials.