By Matthew E. Fink, MD
Louis and Gertrude Feil Professor and Chair, Department of Neurology, Associate Dean for Clinical Affairs, New York Presbyterian/Weill Cornell Medical College
SOURCE: Langezaal LCM, van der Hoeven EJRJ, Mont’Alverne FJA, et al; BASICS Study Group. Endovascular therapy for stroke due to basilar-artery occlusion. N Engl J Med 2021;384:1910-1920.
Basilar artery occlusion is a rare form of ischemic stroke and accounts for about 10% of large vessel occlusions reported in the literature. However, it is associated with a high morbidity and mortality. Studies of endovascular thrombectomy have focused predominantly on occlusions in large vessels of the anterior circulation, and there are very few randomized trials examining the efficacy of thrombectomy in basilar artery occlusion. This is because of the relative rarity of the condition, the difficulty in enrolling patients, and the biases that exist among treating physicians. These investigators conducted a randomized trial, enrolling patients from 2011 through 2019, even though multiple studies published in 2015 demonstrated benefit of endovascular therapy in anterior circulation large vessel occlusions. Efficacy and safety were compared with medical therapy in patients who underwent endovascular therapy within six hours after the estimated time of onset of symptoms. Patients also were treated with intravenous alteplase within four and a half hours.
Randomization was in a 1:1 ratio to receive endovascular therapy or standard medical care. The primary outcome was a favorable neurological outcome as defined by a Rankin scale score of 0 to 3 at 90 days. The primary safety outcomes were symptomatic intracranial hemorrhage within three days of treatment and mortality at 90 days. Three hundred patients were enrolled and divided evenly between the two groups. Intravenous alteplase was administered in 78.6% of the endovascular group and 79.5% in the medical group. Endovascular treatment was initiated at a median of 4.4 hours from onset of stroke symptoms. A favorable outcome, a Rankin scale score of 0 to 3, occurred in 44.2% of the endovascular group and in 37.7% in the medical care group, with a risk ratio of 1.18, 95% confidence interval = 0.92 to 1.50. The wide confidence interval resulted in a lack of statistical significance between the two groups, but it still is possible that endovascular treatment resulted in better outcomes. Symptomatic intracranial hemorrhage occurred in 4.5% of endovascular patients and 0.7% of medical therapy patients, and mortality at 90 days was 38.3% vs. 43.2%. None of the outcomes showed significant differences between the two groups. Because of difficulty in enrollment and the small numbers of patients in each group, many questions remain unanswered. Larger trials will be needed to provide a definitive answer regarding the efficacy of endovascular therapy for basilar artery occlusion.