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DAPT vs. Aspirin Monotherapy in Diabetics Undergoing CABG
Study Questions:
What are the dual antiplatelet therapy (DAPT) utilization rates and associated outcomes among post-coronary artery bypass grafting (CABG) patients with diabetes?
Methods:
In a post-hoc, nonrandomized analysis from the FREEDOM (Future REvascularization Evaluation in patients with Diabetes mellitus: Optimal management of Multivessel disease) trial, the investigators compared patients receiving DAPT (aspirin plus thienopyridine) and aspirin monotherapy at 30 days postoperatively. The primary outcome was the risk-adjusted 5-year FREEDOM composite of all-cause mortality, nonfatal myocardial infarction, or stroke. Safety outcomes included major bleeding, blood transfusion, and hospitalization for bleeding. The differences between the two treatment groups were tested using Kruskal-Wallis test statistics. The times to primary, secondary, and safety outcomes were analyzed using Cox proportional hazard regression.
Results:
At 30 days post-CABG, 544 (68.4%) patients received DAPT and 251 (31.6%) patients received aspirin alone. The median duration of clopidogrel therapy was 0.98 (0.23-1.91) years. There was no significant difference in the 5-year primary composite outcome between DAPT and aspirin-treated patients (12.6% vs. 16.0%, adjusted hazard ratio [HR], 0.83; 95% confidence interval [CI], 0.54-1.27; p = 0.39). The 5-year primary composite outcomes were similar for patients receiving DAPT versus aspirin monotherapy respectively, in subgroups with pre-CABG acute coronary syndrome (15.2% vs. 16.5%, HR, 1.06; 95% CI, 0.53-2.10; p = 0.88) and those with stable angina (11.6% vs. 15.8%, HR, 0.82; 95% CI, 0.50-1.343; p = 0.42). The composite outcomes of both treatment groups were also similar by SYNTAX score, duration of DAPT therapy, completeness of revascularization, and in off-pump CABG. No treatment-related differences in major bleeding (5.6% vs. 5.7%, HR, 1.00; 95% CI, 0.50-1.99; p = 0.99), blood transfusions (4.8% vs. 4.5%, HR, 1.09; 95% CI, 0.51-2.34; p = 0.82), or hospitalization for bleeding (2.6% vs. 3.3%, HR, 0.85; 95% CI, 0.34-2.17; p = 0.74) were observed between aspirin and DAPT-treated patients, respectively.
Conclusions:
The authors concluded that compared with aspirin monotherapy, no associated differences were observed in cardiovascular or bleeding outcomes, suggesting that routine use of DAPT may not be clinically warranted.
Perspective:
This post-hoc secondary analysis of the FREEDOM trial with centrally adjudicated clinical outcomes compared aspirin monotherapy with DAPT post-CABG in patients with diabetes and reports that there were no significant differences in either the primary composite outcome (all-cause death, MI, or stroke) or bleeding outcomes between aspirin and DAPT-treated patients. Furthermore, results were similar across clinically important subgroups including preoperative acute coronary syndrome, SYNTAX score, complete revascularization, and duration of DAPT. The routine use of DAPT in post-CABG diabetic patients should be reassessed in an adequately powered, prospective, randomized clinical outcome trial.
Keywords: Acute Coronary Syndrome, Angina, Stable, Aspirin, Blood Transfusion, Cardiac Surgical Procedures, Coronary Artery Bypass, Diabetes Mellitus, Hemorrhage, Myocardial Infarction, Myocardial Revascularization, Platelet Aggregation Inhibitors, Stroke, Ticlopidine, Treatment Outcome
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