Multiarterial coronary artery bypass grafting (CABG) was linked to lower rates of long-term mortality, reintervention and MI than single-arterial CABG in a recent study of heart patients, suggesting the multiarterial approach is underused in contemporary practice.
Writing in the Journal of the American College of Cardiology, Joanna Chikwe, MD, and colleagues said that while arterial coronary bypass grafts were long ago recognized as superior to venous bypass grafts alone in patients undergoing CABG, it’s unclear whether single or multiarterial CABG is the most favorable approach. The authors said that outcomes of single-arterial versus multiarterial CABG have been compared in randomized clinical trials, but those trials showed no incremental survival benefit in intention-to-treat analyses.
“Randomization is the only way to control for unmeasured confounding variables and selection bias, but such trials require many years to generate adequate follow-up, involve highly selected patients and surgeons, and are commonly underpowered to detect important clinical differences,” Chikwe, of the Icahn School of Medicine at Mount Sinai and the State University of New York, et al. wrote in the journal.
Analyzing clinical registries, on the other hand, could generate additional information about the surgeries, including longer-term outcomes in larger populations more representative of today’s healthcare landscape.
Chikwe and co-authors drew from mandatory clinical registries and discharge databases to identify the baseline and operative characteristics and outcomes of 42,714 patients who underwent CABG between 2005 and 2012. Patients with single-vessel disease, without arterial conduits or undergoing emergency, reoperative or concomitant procedures were excluded, making for a study population of 26,124 patients.
Of that pool, 3,647—or 14%—underwent multiarterial CABG, the authors reported. Single-arterial CABG patients were on average older than their multiarterial peers (68 vs. 61 years old), had more comorbidities and received fewer bypass grafts (3.4 vs. 3.6).
After adjusting for baseline characteristics, the team found that multiarterial CABG was associated with lower 10-year mortality than single-arterial CABG in 3,588 propensity-matched pairs (15.1% vs. 17.3%). The multiarterial method was also linked to a 19% reduced risk of 10-year MI and a 19% lower 10-year intervention risk.
In a related editorial, the University of Oxford’s David P. Taggart, MD, PhD, said that while Chikwe et al.’s findings “supported an enormous body of other observational data that reported benefits of multiple arterial grafts (MAGs),” they should be interpreted in the context of the recent ART (Arterial Revascularization Trial) study.
Findings from ART, a randomized trial of 3,102 patients using single internal thoracic artery (ITA) or bilateral ITA (BITA) grafts, were published in the New England Journal of Medicine earlier this year. In a nutshell, the authors found an absolute survival benefit with BITA grafts of around 5%, and in an as-treated analysis 10-year survival curves implied patients might see an even greater mortality benefit in the long-term.
Taggart said that primary finding from ART is similar to Chikwe and colleagues’ outcome of “absolute and accelerating” mortality benefit in favor of MAGs at 10 years.
“Chikwe et al. deserve credit for their comprehensive analysis and for providing data that should help guide decisions regarding the rationale for MAGs and targeting this strategy to particular patient groups,” the editorialist wrote. “However, despite the well-matched baseline characteristics in the propensity-matched analysis by Chikwe et al. and in the as-treated analysis in the ART study, the potential for confounding by unrecognized biases and the influence of surgeon experience remain to be resolved.”