Randomized trial of clazosentan in patients with aneurysmal subarachnoid hemorrhage undergoing endovascular coiling

Background and Purpose— Clazosentan, an endothelin receptor antagonist, has been shown to reduce vasospasm after aneurysmal subarachnoid hemorrhage (aSAH). CONSCIOUS-3 assessed whether clazosentan reduced vasospasm-related morbidity and all-cause mortality postaSAH secured by endovascular coiling. Methods— This double-blind, placebo-controlled, phase III trial randomized patients with aSAH secured by endovascular coiling to ≤14 days intravenous clazosentan (5 or 15 mg/h) or placebo. The primary composite end point (all-cause mortality; vasospasm-related new cerebral infarcts or delayed ischemic neurological deficits; rescue therapy for vasospasm) was evaluated 6 weeks postaSAH. The main secondary end point was dichotomized extended Glasgow Outcome Scale (week 12). Results— CONSCIOUS-3 was halted prematurely following completion of CONSCIOUS-2; 577/1500 of planned patients (38%) were enrolled and 571 were treated (placebo, n=189; clazosentan 5 mg/h, n=194; clazosentan 15 mg/h, n=188). The primary end point occurred in 50/189 of placebo-treated patients (27%), compared with 47/194 patients (24%) treated with clazosentan 5 mg/h (odds ratio [OR], 0.786; 95% CI, 0.479–1.289; P= 0.340), and 28/188 patients (15%) treated with clazosentan 15 mg/h (OR, 0.474; 95% CI, 0.275–0.818; P= 0.007). Poor outcome (extended Glasgow Outcome Scale score ≤4) occurred in 24% of patients with placebo, 25% of patients with clazosentan 5 mg/h (OR, 0.918; 95% CI, 0.546–1.544; P= 0.748), and 28% of patients with clazosentan 15 mg/h (OR, 1.337; 95% CI, 0.802–2.227; P= 0.266). Pulmonary complications, anemia, and hypotension were more common in patients who received clazosentan than in those who received placebo. At week 12, mortality was 6%, 4%, and 6% with placebo, clazosentan 5 mg/h, and clazosentan 15 mg/h, respectively. Conclusions— Clazosentan 15 mg/h significantly reduced postaSAH vasospasm-related morbidity/all-cause mortality; however, neither dose improved outcome (extended Glasgow Outcome Scale). Clinical Trial Registration— URL: http://clinicaltrials.gov . Unique identifier: NCT00940095.