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Recent years gave multi-arterial bypass grafting (MABG) a small boost in utilization, though overcoming the substantial learning curve remains a challenge for many surgeons, according to records from the Society of Thoracic Surgeons (STS) Adult Cardiac Surgery Database.

Across the U.S., the more than 900 hospitals offering coronary artery bypass grafting (CABG) surgery averaged 14% in MABG utilization in 2018-2019, reported Siavash Saadat, MD, of Baystate Medical Center in Springfield, Massachusetts, and other centers, at the STS virtual meeting.

Noting significant regional and institutional variability, he said that both bilateral internal thoracic artery (BITA) and radial artery (RA) MABG continue to be underutilized in the U.S. Nevertheless, a 14% uptake of these technically complex procedures is still a small increase from the 10% .

STS session co-moderator Jennifer Lawton, MD, of Johns Hopkins University in Baltimore, said it was "disheartening" how low the rates of MABG are, even with national guideline endorsement. "I did four [of these] this week," she said.

The data suggest that even in expert hands, patient outcomes improved with more center experience with MABG. Although the relationship between institutional case volumes and outcomes is complex and multifactorial, the findings are in line with an existing learning curve in MABG, according to Saadat.

He said future work is needed to identify strategies to help CABG operators overcome this learning curve.

MABG has been associated with improved late outcomes in past observational studies. The ART trial, however, could not definitively show a benefit of this strategy over single arterial grafting in terms of survival at 10 years.

The present report included 281,515 people who had isolated primary non-emergent CABG. Single arterial grafting accounted for the majority of surgeries, with BITA and RA MABG comprising 5.6% and 8.5%, respectively.

People getting MABG tended to be men in their early 60s. Recipients of single grafting were older and sicker.

Total MABG operative times were about 360 minutes, compared with 318 minutes for single grafting, due to longer cross clamp times and cardiopulmonary bypass times.

Saadat's group found that perioperative outcomes were "uniformly excellent" after single and multiple arterial grafting with few exceptions:

• Single arterial bypass grafting: mortality average 2.1% (risk-adjusted observed to expected [O/E] ratio 1.00), major morbidity and mortality 11.1% (O/E 1.00), deep sternal wound infection 0.7% (O/E 0.96)
• Radial MABG: mortality 1.4% (O/E 0.96), major morbidity and mortality 8.7% (O/E0.97), deep sternal wound infection 0.6% (O/E0.90)
• BITA MABG: mortality 1.2% (O/E 0.98), major morbidity and mortality 7.6% (O/E 1.13), deep sternal wound infection 0.5% (O/E 1.91)

BITA MABG's higher morbidity and mortality was apparently driven by increased deep sternal wound infection. Whether this is a surgeon-specific issue, a matter of patient selection, or an institutional problem is unclear, Saadat stated.

Session co-moderator Faisal Bakaeen, MD, of Cleveland Clinic, said he would have liked to see findings on individual operator volume and its potential effect on MABG outcomes.

Saadat acknowledged that his group lacked such granular data, along with other important variables such as skeletonization of the arteries and pre- and perioperative management (e.g., glycemic control), in the present report.

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