New Publication in Journal of the American College of Cardiology

This large national analysis of over 1.2 million Medicare beneficiaries tackled a long-standing question in cardiac surgery: does multiarterial grafting (MAG) during coronary artery bypass grafting truly improve survival over single arterial grafting (SAG)? Using flexible parametric survival models with time-dependent effects and regression standardisation to derive standardised survival probabilities, two analytical approaches were compared head-to-head – a conventional risk-adjusted model and an instrumental variable (IV) model using surgeon MAG rate as the instrument. The conventional model suggested a modest survival advantage for MAG, consistent with prior observational literature. However, this association was not observed in the IV model, suggesting the observed survival benefit may be driven by unmeasured confounding related to patient selection and surgeon decision-making rather than the procedure itself.

Publication details

Schaffer J, Shih E, Squiers J, Banwait J, Hale S, Gasparini A, Mack M, DiMaio J. Multiarterial Grafting and Survival After Coronary Artery Bypass Grafting. Journal of the American College of Cardiology 2026.

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