What is the optimal antiplatelet therapy in patients with chronic coronary syndrome undergoing coronary artery bypass grafting?

OBJECTIVE: Patients with chronic coronary syndrome (CCS) make up a large portion of those undergoing coronary artery bypass grafting (CABG), and there are significant gaps in the evidence regarding the optimal aspirin dosage after CABG and whether dual antiplatelet therapy (DAPT) should be initiated after CABG. Therefore, we aimed to address this issue. METHODS: Between January-2010 and June-2022, 1607-patients who underwent primary isolated CABG with CCS were included in the final analysis and divided into three groups according to their discharge antiplatelet treatment: patients receiving 75 mg of aspirin (n = 526), patients receiving 300 mg of aspirin (n = 825) and patients receiving DAPT consisting of aspirin 75 mg and clopidogrel 75 mg (n = 256). Three separate propensity-matched analyses were performed: aspirin 75 mg vs aspirin 300 mg, DAPT vs aspirin 75 mg and aspirin 300 mg vs DAPT. Primary endpoint was long-term incidence major adverse cardiac and cerebral events (MACCE), defined as the composite of all-cause mortality, myocardial infarction, repeat revascularization and stroke. Furthermore, 497 angiograms were retrieved at follow-up and graft patency was evaluated. RESULTS: In the matched cohort, aspirin 300 mg and DAPT, compared with aspirin 75 mg at discharge, were associated with reduced incidence of MACCE (HR:0.65; 95% CI 0.48-0.86; adjusted P = 0.009) and (HR:0.62; 95% CI 0.41-0.93; adjusted P = 0.04), respectively. However, the incidence of MACCE was comparable between aspirin 300 mg and DAPT at follow-up (HR:0.86; 95% CI 0.55-1.33; adjusted P = 0.50). As for the retrieved angiograms at follow-up, aspirin 300 mg and DAPT were associated with a lower incidence of any graft failure (19.2% vs. 25.8%; P = 0.009) and (14.7% vs. 25.8%; P = 0.007), respectively, compared with aspirin 75 mg. On the other hand, aspirin 300 mg and DAPT had comparable incidence of any graft failure. CONCLUSIONS: In patients with CCS following CABG, discharge treatment with 300 mg aspirin or DAPT was associated with a lower incidence of MACCE and better graft patency than 75 mg aspirin; however, these findings should be interpreted cautiously given the observational design and potential for residual confounding.