Bypass Surgery for Multivessel CAD Reaffirmed in Newer Data

SAN DIEGO -- The recently weakened endorsement of coronary artery bypass grafting (CABG) for multivessel disease is not supported by contemporary real-world data, heart surgeons argued.

Based on over 100,000 Medicare beneficiaries presenting with acute coronary syndrome (ACS) who underwent revascularization, risk-adjusted rates of death, myocardial infarction (MI), heart failure, acute kidney injury, and readmissions at 30 days after discharge all favored CABG over multivessel percutaneous coronary intervention (PCI).

Moreover, CABG was associated with improved 3-year survival (HR 0.448, 95% CI 0.437-0.458) and the composite endpoint of reintervention, MI, and death (HR 0.476, 95% CI 0.46-0.493). Longitudinal outcomes favored CABG in key subgroups of patients older than 75 years and those with baseline diabetes, heart failure, or non-ST-segment elevation MI (NSTEMI).

Only stroke readmission rates did not significantly favor CABG over PCI after risk adjustment of longitudinal outcomes, reported J. Hunter Mehaffey, MD, MSc, a cardiac surgeon at West Virginia University in Morgantown, during this year's meeting of the Society of Thoracic Surgeons (STS).

"These longitudinal data support the superiority of CABG compared to PCI and may have current and future policy and practice implications," Mehaffey said, adding that he wished to "take back the narrative about bypass surgery to make sure patients are getting optimal treatment."

Fellow surgeon Joseph Sabik, III, MD, of University Hospitals Cleveland Medical Center, called this an important study with "impressive" findings that should prompt reevaluation of the recent controversial guideline change that had not been endorsed by surgeon societies -- namely the STS and the American Association for Thoracic Surgery.

The controversy erupted in 2021 when American guidelines downgraded CABG from class I to class IIb, on par with PCI, in multivessel disease and normal left ventricular ejection fraction in stable ischemic heart disease. This change was attributed to the guideline writers considering only the most recent studies from the prior 5 years -- meaning the downgrade of CABG was based largely on the ISCHEMIA trial that had found an initial invasive approach to be no better than medical therapy alone in stable coronary artery disease.

Yet ISCHEMIA was not representative of patients undergoing CABG and failed to capture those with multivessel disease in particular, Mehaffey argued.

Sabik, speaking as the STS session discussant, pointed out that the controversy is in stable ischemic disease, whereas the study by Mehaffey's group covers an ACS population. Nevertheless, the results at least raise the question of whether CABG should be the preferred therapy for all patients with ACS, Sabik said.

Mehaffey acknowledged the disparate patient populations being discussed but warned of guideline creep as "many clinical providers do not read the fine print," only reviewing the executive summary or a lay media report. He reminded the audience that his results persisted in NSTEMI.

Sabik also cautioned that the improved clinical outcomes after CABG surgery came at the cost of greater in-hospital morbidity: In-hospital outcome of death favored CABG, whereas PCI was associated with less bleeding, stroke, acute kidney injury, and acute renal failure.

Moreover, CABG was associated with significantly higher hospital cost compared with PCI ($57,189 vs $36,342, P< 0.001) and longer total hospital stays (11.9 days vs 5.8 days, P<0.001), the study authors found.

Aiming to give guideline committees the contemporary data that they want, Mehaffey and colleagues had limited their analysis to Medicare beneficiaries presenting from January 2018 to December 2020.

The observational study relied on a database of Centers for Medicare & Medicaid Services inpatient claims. Participants were people who underwent CABG (n=51,389) or multivessel PCI (n=52,738), excluding those with a history of concomitant valvular procedures, prior CABG, and heart transplantation.

Compared with the PCI arm, CABG recipients were younger (72.9 vs 75.2 years, P<0.001) but tended to have a higher Elixhauser Comorbidity Index (5.0 vs 4.2, P<0.001), and a higher likelihood of diabetes (48.5% vs 42.2%, P<0.001). The CABG cohort also had lower rates of ST elevation MI at presentation (14.4% vs 29.0%, P<0.001).

The groups were relatively well-balanced after matching by inverse probability of treatment weighting propensity scores.

Nevertheless, the observational analysis remained subject to potential confounding and biases inherent in its nonrandomized design.

"The findings of our study were very convincing," Mehaffey maintained in a press release. "The singular message to the public is that the optimal treatment for multivessel coronary artery disease -- to improve not only long-term survival but also lower your risk of complications -- is coronary artery bypass surgery."

"These contemporary real-world data support prior existing trials highlighting the benefits of CABG in multivessel coronary artery disease, urging a re-evaluation of recent guidelines," he said.

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