Impact of previous coronary artery bypass grafting in patients presenting with an acute coronary syndrome: Current trends and clinical implications.

Background: Among patients presenting with an acute coronary syndrome, those with previous coronary artery bypass grafting are a particular subset.

Aims: The purpose of this study was to investigate the prognostic impact of previous coronary artery bypass grafting in acute coronary syndrome patients and to identify the current trends in their clinical management.

Methods: We performed a cohort analysis of patients prospectively enrolled in the Portuguese Registry of acute coronary syndrome between 2010-2019 with known previous coronary artery bypass grafting status. The co-primary endpoints were in-hospital and one-year mortality.

Results: A total of 19,334 (962 coronary artery bypass grafting and 18,372 non-coronary artery bypass grafting) and 9402 (479 coronary artery bypass grafting and 8923 non-coronary artery bypass grafting) patients were included in the analyses of in-hospital and mid-term outcomes, respectively. Coronary artery bypass grafting patients were older and had a higher incidence of comorbidities. They were less likely to undergo invasive angiography (74.9 vs 84.6%, <0.001), but were equally likely to receive dual antiplatelet therapy (91.0 vs 90.8%, =0.823). In-hospital mortality was similar between groups (3.6 vs 3.4%, =0.722). Unadjusted one-year mortality was higher in the coronary artery bypass grafting group (hazard ratio 1.48, 95% confidence interval 1.09-2.01, =0.012), but similar in both groups after propensity-matching and multivariate analysis (hazard ratio 0.63, 95% confidence interval 0.37-1.09, =0.098).

Conclusions: Among patients with acute coronary syndrome, a previous history of coronary artery bypass grafting was associated with a high burden of comorbidities and a high-risk profile but was not an independent predictor of adverse events. Treatment decisions should be made on a case-by-case basis, and should not be based on previous coronary artery bypass grafting status alone.