in the latest randomized trial comparing the two interventions.
However, subgroup analyses suggest a potential benefit of surgery for certain patients, such as those with MCA vs. ICA occlusion, mean transit time greater than 6 seconds, or regional blood flow of 0.8 or less.
“We were disappointed by the results,” Liqun Jiao, MD, of the National Center for Neurological Disorders in Beijing, told this news organization. “We were expecting to demonstrate a benefit from EC-IC bypass surgery over medical treatment alone in symptomatic patients with ICA or MCA occlusion and hemodynamic insufficiency, per our original hypothesis.”
Although the study showed improved efficacy and safety for the surgical procedure, he said, “The progress of medical treatment is even better.”
The study was published online in JAMA.
Subgroup analyses promising
Previous randomized clinical trials, including the EC/IC Bypass Study and the Carotid Occlusion Surgery Study (COSS), showed no benefit in stroke prevention for patients with atherosclerotic occlusion of the ICA or MCA.
However, in light of improvements over the years in surgical techniques and patient selection, the authors conducted the Carotid and Middle Cerebral Artery Occlusion Surgery Study (CMOSS), a multicenter, randomized, open-label trial comparing EC-IC bypass surgery plus medical therapy, consisting of antiplatelet therapy and control of stroke risk factors, with medical therapy alone in symptomatic patients with ICA or MCA occlusion and hemodynamic insufficiency, with refined patient and operator selection.
A total of 324 patients (median age, 52.7 years; 79% men) in 13 centers in China were included; 309 patients (95%) completed the study.
The primary outcome was a composite of stroke or death within 30 days or ipsilateral ischemic stroke beyond 30 days through 2 years after randomization.
Secondary outcomes included, among others, any stroke or death within 2 years and fatal stroke within 2 years.
No significant difference was found for the primary outcome between the surgical group (8.6%) and the medical group (12.3%).
The 30-day risk of stroke or death was 6.2% in the surgery group, versus 1.8% (3/163) for the medical group. The risk of ipsilateral ischemic stroke beyond 30 days through 2 years was 2%, versus 10.3% – nonsignificant differences.
Furthermore, none of the prespecified secondary endpoints showed a significant difference, including any stroke or death within 2 years (9.9% vs. 15.3%; hazard ratio, 0.69) and fatal stroke within 2 years (2% vs. none).
Despite the findings, “We are encouraged by the subgroup analysis and the trend of long-term outcomes,” Dr. Jiao said. “We will continue to finish 5-10 years of follow-up to see whether the benefit of bypass surgery can be identified.”
The team has also launched the CMOSS-2 trial with a refined study design based on the results of subgroup analysis of the CMOSS study.
CMOSS-2 is recruiting patients with symptomatic chronic occlusion of the MCA and severe hemodynamic insufficiency in 13 sites in China. The primary outcome is ischemic stroke in the territory of the target artery within 24 months after randomization.