Determining the Optimal Age for Extracranial-Intracranial Bypass Surgery: A Post Hoc Analysis of the CMOSS Randomized...

Previous trials have failed to demonstrate the benefits of extracranial-intracranial (EC-IC) bypass surgery for patients with carotid or middle cerebral artery occlusion. However, little evidence has focused on the effect of age on prognosis. This study aimed to explore whether EC-IC bypass surgery can provide greater benefits than medical therapy alone in specific age groups.

A post hoc analysis was performed of the CMOSS (Carotid or Middle Cerebral Artery Occlusion Surgery Study), which was a randomized, open-label, outcome assessor-blinded trial conducted at 13 centers in China between June 2013 and March 2018. A total of 324 patients with internal carotid artery or middle cerebral artery occlusion with transient ischemic attack or nondisabling ischemic stroke attributed to hemodynamic insufficiency were randomized into a surgical group (n=161) that underwent EC-IC bypass surgery with medical therapy, and a medical group (n=163) that received antiplatelet therapy and stroke risk factor control alone. The primary outcome was a composite of stroke or death within 30 days or ipsilateral ischemic stroke beyond 30 days up to 2 years after randomization. Receiver operating characteristic curves were drawn to explore the optimal age boundary, and survival analyses were used to explore differences between groups.

Among the 324 patients (median age, 52.7 years; 79.3% men), an age cutoff of 55.5 years predicted the primary outcome in the surgical group (area under the curve, 0.649 [95% CI, 0.530-0.769]). Patients were further divided into an older group (>55.5 years) and a younger group (≤55.5 years). Younger patients who underwent bypass surgery showed a lower risk of the primary outcome (log-rank P=0.001) than older patients. Patients who underwent EC-IC bypass surgery had a lower risk than patients with medical therapy alone in the younger group (3.2% versus 11.6%; hazard ratio, 0.255 [95% CI, 0.071-0.916]; P=0.036), but not in the older group (17.5% versus 13.3%; adjusted hazard ratio, 0.597 [95% CI, 0.225-1.580]; P=0.298).

In patients aged 55.5 years or younger with symptomatic atherosclerotic occlusion of the internal carotid artery or middle cerebral artery and hemodynamic insufficiency, the addition of EC-IC bypass surgery to medical therapy significantly improved prognosis. These findings suggest that the clinical application of EC-IC bypass surgery needs more research to explore refined patient selection criteria incorporating more clinical features.

URL: https://www.clinicaltrials.gov; Unique identifier: NCT01758614.