Compared to on-pump coronary artery bypass grafting (CABG), off-pump surgery is associated with lower rates of revascularization and a significantly increased risk of all-cause death at three years, according to an analysis of the EXCEL trial.
CABG is an industry standard for treating left main disease and has long been considered both safe and effective, Umberto Benedetto, MD, PhD, and co-authors wrote in the Journal of the American College of Cardiology, but on-pump surgery comes with a well-known risk of surgical morbidity. For that reason, off-pump CABG—surgery without cardiopulmonary bypass—grew in popularity in the early 2000s, reaching a peak of 23% prevalence in the U.S. in 2002.
Still, off-pump CABG presented its own fair share of challenges, including controversial long-term effects, lower rates of complete revascularization and a technical complexity that limited the procedure to the most experienced surgeons. Today, most cardiac surgeons perform fewer than 20 off-pump cases per year.
Benedetto et al. compared on- versus off-pump outcomes among 923 patients enrolled in the EXCEL trial, which was designed to compare outcomes of percutaneous coronary intervention with an everolimus-eluting stent to CABG in heart patients with left main disease. Of that group, 652 subjects underwent on-pump surgery, while 271 were referred for an off-pump procedure.
Despite a similar extent of disease, the authors found that off-pump surgery was linked to a lower rate of revascularization of the left circumflex coronary artery (84.1% vs. 90% in on-pump patients) and the right coronary artery (31.1% vs. 40.6%, respectively). Off-pump CABG remained the riskier approach even after adjusting for baseline differences—off-pump surgery was associated with an 8.8% increased risk of all-cause death at three years post-op while on-pump surgery was associated with a 4.5% increased risk of death.
The authors also noted a nonsignificant difference in risk for a composite endpoint of death, MI or stroke between the groups (11.8% in off-pump vs. 9.2% in on-pump patients).
“The two groups presented similar incidence of major adverse events during index hospitalization except for a lower incidence of any unplanned surgery or therapeutic radiological procedure and post-operative atrial fibrillation/flutter (19.2% vs. 26.5%), which were significantly lower in the off-pump group,” Benedetto and colleagues wrote in JACC. “At three years, off-pump surgery was associated with a significant twofold increase in mortality, an outcome that remained robust after adjustment for confounders in several different models.”
In an editorial comment, Faisal G. Bakaeen, MD, and Lars G. Svensson, MD, PhD, said the modern-day debate about on- versus off-pump CABG has shifted to focus on surgeons’ experience and skill and identifying a subgroup of CABG candidates who might be best suited for off-pump surgery. While the CORONARY and GOCABE trials both failed to identify a survival difference between on- and off-pump CABG at five years, a 2018 meta-analysis found a direct link between surgeon inexperience and late mortality.
“Off-pump CABG is probably best performed by surgeons experienced and skilled in this technique and in select patients whose risk profile may be more conducive to an off-pump strategy,” the editorialists wrote, noting no randomized study to date has found a major post-op advantage for off-pump CABG. “Intuitively, the benefits of off-pump CABG may be derived in selected high-risk patients, especially those at increased risk for cardiopulmonary bypass or aortic manipulation, such as patients with advanced cirrhosis or atheromatous disease of the ascending aorta.
“Such extreme patients are underrepresented or excluded in randomized trials. Nonetheless, it is important to acknowledge that off-pump CABG may be the procedure of choice for these high-risk patients.”