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Safety of Simultaneous CABG and CEA Versus Isolated CABG
Study Questions:
Which treatment yields better outcomes for patients in need of coronary artery bypass graft surgery (CABG) who also have asymptomatic high-grade carotid artery stenosis: synchronous CABG and carotid endarterectomy (CEA) or isolated CABG?
Methods:
The CABACS (Coronary Artery Bypass graft surgery in patients with Asymptomatic Carotid Stenosis) trial randomized 127 patients with high-grade asymptomatic internal carotid artery stenosis to either CABG with synchronous CEA or CABG alone in a multicenter, open-group sequential trial in Germany. Evaluators of study endpoints were blinded to the treatment. High-grade internal carotid artery stenosis was defined as ≥80% (per European Carotid Surgery Trial ultrasound criteria with main criterion peak systolic velocity ≥300 cm/s, equivalent to ≥70% by North American Symptomatic Carotid Endarterectomy Trial definition).
Results:
Initial study design planned for 2 panels of 580 patients, each with a total of 1,160 patients. After randomization of 127 participants from 17 centers into the intention-to-treat protocols, enrollment in the trial was terminated early due to withdrawal of funding after insufficient recruitment. Patients were followed at 7 days, 30 days, 1 year, and for up to 5 years following surgery. The 5-year follow-up remains ongoing. Primary outcome was any stroke or death occurring up to 30 days after surgery or after randomization (if surgery was not performed in violation of protocol). Primary outcome results showed the following:
- For the entire intention-to-treat cohorts, 18.5% (12 of 65) of patients in the CABG with CEA cohort experienced stroke or death within 30 days following surgery or randomization compared with 9.7% (6 of 62) of those in the isolated CABG cohort. Results (p = 0.12) did not achieve statistical significance.
- In the treatment-per-protocol cohorts, 19.6% (11 of 56) patients treated with CABG and CEA experienced stroke or death within 30 days following surgery versus 11.3% (6 of 53) in those treated with isolated CABG. Results (p = 0.21) again did not achieve statistical significance
A total of 25 secondary outcomes was defined: any stroke or death within 1 year of surgery or randomization, duration of ventilatory support, intervention failure, length of hospital stay, and duration of intensive care unit stay. Secondary endpoints assessed at both 30 days and 1 year included any death; any stroke; any myocardial infarction; disabling stroke; ipsilateral ischemic stroke; combined stroke or vascular death; combined stroke, death, or myocardial infarction; change in DemTect score; decrease in DemTect score; and modified Rankin scale >1. The rate of stroke or death within 1 year following surgery or randomization in the CABG with CEA group was 23.4% versus 13.1% in the CABG only group (p = 0.17). For most of the secondary endpoints, absolute event rates for CABG with CEA were higher than for isolated CABG. However, there was not a statistically significant difference (defined as p ≤ 0.05) detected in any of the secondary endpoints in either the intention-to-treat groups or the per-protocol groups. The authors state that the study was underpowered to demonstrate statistically significant effects for the expected clinical outcome. They are cautious to draw conclusions regarding the safety of isolated CABG but note that the very high rate of perioperative stroke does not seem to justify simultaneous CEA and CABG in patients with high-grade asymptomatic carotid artery stenosis.
Conclusions:
The CABG with CEA cohort had nearly double the rate of stroke or death within 30 days or within 1 year compared with CABG alone, but the data did not reach statistical significance. The high rate (16-18%) of perioperative stroke, however, does not seem to merit simultaneous CABG with CEA in patients with asymptomatic high-grade internal carotid artery stenosis. This trial was terminated early due to withdrawal of funding after insufficient recruitment, and the authors indicate that the trial did not achieve sufficient statistical power to demonstrate the expected clinical outcome.
Perspective:
The authors state that this is the first rigorously designed, multicenter randomized controlled trial to investigate combination CEA with CABG compared with CABG only in patients with high-grade asymptomatic internal carotid artery stenosis requiring coronary bypass surgery. Two prior randomized controlled trials suggested a lower perioperative risk of stroke in patients treated with combined CABG and CEA as opposed to CABG and delayed, staged CEA. The authors suggest that further studies should evaluate staged CEA or carotid stenting followed by CABG compared with isolated CABG without carotid intervention.
Keywords: Endarterectomy, Carotid, Coronary Artery Bypass, Carotid Stenosis, Stroke, Myocardial Infarction, Stents
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