Outcomes among patients with coronary artery bypass grafts presenting with acute coronary syndrome: impact of revascularization.

Background: Patients post-coronary artery bypass graft (CABG) can re-present with acute coronary syndrome (ACS); however, culprit lesion identification, as well as revascularization, is often challenging. Furthermore, the impact of revascularization in this patient group is relatively unknown.

Objectives: The purpose of our study was to evaluate the efficacy of percutaneous coronary intervention (PCI) in patients with previous CABG surgery presenting with ACS.

Methods: Using data from the Manitoba Center for Health Policy, we identified patients treated with CABG between April 1979 and March 2018, who subsequently presented with the primary diagnosis of ACS. Patients were divided into four groups: (1) managed medically and not investigated by cardiac catheterization and (2) investigated by cardiac catheterization and treated (2a) medically, (2b) with PCI, and (2c) with redo-CABG. Inverse probability treatment-weighted survival analyses were performed. Ethical approval was obtained from the local research board.

Results: Nearly 20% of patients treated with CABG presented with ACS at a median of 7.2 years (age at the time of CABG: 66 years (interquartile range: 58-73 years); 75.6% male). Patients treated with PCI (N = 929) demonstrated improved survival compared to the patients investigated by catheterization but treated medically (N = 952; hazard ratio 0.87, 95% confidence interval 0.77-0.97, p = 0.02). Patients who underwent redo CABG (N = 171) experienced 13% mortality within the first year, but subsequently, demonstrated a trend toward improved survival.

Conclusion: ACS is not uncommon following CABG. Revascularization is associated with prognostic improvement; however, such could be accounted for by inherent group differences, including comorbidities and coronary anatomy These findings should be validated in a prospective randomized study.