Multi-arterial Coronary Artery Bypass Grafting Practice Patterns in the USA: Analysis of The Society of Thoracic Surgeons Adult Cardiac Surgery Database

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Background: We aim to elucidate current national multi-arterial bypass grafting practice patterns and assess perioperative outcomes.

Methods: Isolated primary non-emergent/non-salvage coronary artery bypass grafting patients with at least one internal thoracic artery and two or more grafts in STS Adult Cardiac Surgery Database(2018-2019) were divided into three cohorts: single-arterial, bilateral internal thoracic artery(BITA-MABG) and radial artery(RA-MABG). Observed-to-expected ratios based on 2017 STS risk models were derived for 30-day peri-operative mortality and composite major morbidity and mortality, as well as deep sternal wound infections, for each grafting group overall and as a function of institutional multi-arterial case volumes: low(<10), intermediate(11-30), high(>30)/study period.

Results: 281,515 patients [BITA-MABG=15,663(5.6%); RA-MABG=23,905(8.5%)] at 1013 centers showed distinct geographical grafting patterns: BITA-MABG/RA-MABG rates were lowest in the South(4%/6%) and highest in the Northeast(9%/11%). The median institutional number of BITA-MABG and RA-MABG cases/study period was 4 and 7, with only 14% and 21% of institutions performing >30 BITA-MABG and RA-MABG cases/study period, respectively. The observed-to-expected mortality(95%CI) for single-arterial was similar to multi-arterial: single-arterial[1.00(0.98-1.03)], BITA-MABG[0.98(0.84-1.13)], p=0.711, and RA-MABG[0.96(0.86-1.07)], p=0.818. Observed-to-expected mortality and composite major morbidity and mortality(95%CI) were lower at high versus low multi-arterial case volume centers: 0.91(0.75-1.08) versus 1.30(0.89-1.79), p=0.048 and 1.06(0.99-1.13) versus 1.51(1.32-1.71), p<0.001, respectively for BITA-MABG and 0.82(0.87-1.30) versus 1.67(1.21-2.21), p<0.001 and 0.91(0.93-1.08) versus 1.42(1.24-1.61), p<0.001, respectively for RA-MABG.

Conclusions: Multi-arterial bypass grafting remains underutilized and limited to select centers. Worse outcomes at low volume BITA-MABG and RA-MABG institutions document a case-volume outcomes effect. Additional studies are warranted to improve multi-arterial outcomes at low volume institutions.