Comparison of Midterm Outcomes Associated With Aspirin and Ticagrelor vs Aspirin Monotherapy After Coronary Artery Bypass Grafting for Acute Coronary Syndrome

Abstract

Importance: Guidelines recommend dual antiplatelet therapy after coronary artery bypass grafting (CABG) for patients with acute coronary syndrome (ACS). However, the evidence for these recommendations is weak.

Objective: To compare midterm outcomes after CABG in patients with ACS treated postoperatively with acetylsalicylic acid (ASA) and ticagrelor or with ASA monotherapy.

Design, setting, and participants: This cohort study used merged data from several national registries of Swedish patients who were diagnosed with ACS and subsequently underwent CABG. All included patients underwent isolated CABG in Sweden between 2012 and 2017 with an ACS diagnosis less than 6 weeks before the procedure, survived 14 days after discharge from hospital, and were treated postoperatively with ASA plus ticagrelor or ASA monotherapy. A multivariable Cox regression model was used for the main analysis, and propensity score-matched models were performed as sensitivity analysis. Data were analyzed between May and September 2020.

Exposures: Postoperative antiplatelet treatment, defined as filled prescriptions, with either ASA and ticagrelor or ASA only.

Main outcomes and measures: Major adverse cardiovascular events (MACE), defined as all-cause mortality, myocardial infarction, and stroke, and major bleeding, at 12 months and at the end of follow-up.

Results: A total of 6558 patients (5281 [80.5%] men; mean [SD] age at surgery, 67.6 [9.3] years) were included; 1813 (27.6%) were treated with ASA plus ticagrelor and 4745 (72.4%) were treated with ASA monotherapy. Crude MACE rate was 3.0 per 100 person years (95% CI, 2.5-3.6 per 100 person years) in the ASA plus ticagrelor group and 3.8 per 100 person years (95% CI, 3.5-4.1 per 100 person years) in the ASA group. After adjustment, there was no significant difference in MACE risk between ASA plus ticagrelor vs ASA only, neither during the first 12 months (adjusted hazard ratio [aHR], 0.84; 95% CI, 0.58-1.21; P = .34) or during total follow-up (aHR, 0.89; 95% CI, 0.71-1.11; P = .29). The use of ASA plus ticagrelor was associated with a significantly increased risk for major bleeding during the first 12 months (aHR, 1.90; 95% CI, 1.16-3.13; P = .011). Sensitivity analyses confirmed the results.

Conclusions and relevance: In patients with ACS who survived 2 weeks after CABG, no significant difference in the risk of death or ischemic events could be demonstrated between ASA plus ticagrelor and patients treated with ASA only, while the risk for major bleeding was higher in patients treated with ASA plus ticagrelor. Sufficiently powered prospective randomized trials comparing different antiplatelet therapy strategies after CABG are warranted.

Figure 1.. Dispensed Platelet Inhibitors Within 14 Days After Hospital Discharge From CABG, 2012-2017

ASA indicates acetylsalicylic acid; CABG, coronary artery bypass grafting.

Figure 2.. Incidence of MACE and Major Bleeding Events Following CABG

The shaded areas represent 95% CIs. ASA indicates acetylsalicylic acid; MACE, major adverse cardiovascular event.

Figure 3.. Adjusted Hazard Ratios for MACE, Major Bleeding Events, and NACE During Follow-up

MACE indicates major adverse cardiovascular event (all-cause mortality, myocardial infarction, stroke); NACE, net adverse clinical events (all-cause mortality, myocardial infarction, stroke and major bleeding).