Graft Failure After Coronary Artery Bypass Grafting and Its Association With Patient Characteristics and Clinical Events: A Pooled Individual Patient Data Analysis of Clinical Trials With Imaging Follow-Up

BACKGROUND: Graft patency is the postulated mechanism for the benefits of coronary artery bypass grafting (CABG). However, systematic graft imaging assessment after CABG is rare, and there is a lack of contemporary data on the factors associated with graft failure and on the association between graft failure and clinical events after CABG. METHODS: We pooled individual patient data from randomized clinical trials with systematic CABG graft imaging to assess the incidence of graft failure and its association with clinical risk factors. The primary outcome was the composite of myocardial infarction or repeat revascularization occurring after CABG and before imaging. A 2-stage meta-analytic approach was used to evaluate the association between graft failure and the primary outcome. We also assessed the association between graft failure and myocardial infarction, repeat revascularization, or all-cause death occurring after imaging. RESULTS: Seven trials were included comprising 4413 patients (mean age, 64.4±9.1 years; 777 17.6% women; 3636 82.4% men) and 13 163 grafts (8740 saphenous vein grafts and 4423 arterial grafts). The median time to imaging was 1.02 years (interquartile range IQR, 1.00–1.03). Graft failure occurred in 1487 (33.7%) patients and in 2190 (16.6%) grafts. Age (adjusted odds ratio aOR, 1.08 per 10-year increment 95% CI, 1.01–1.15; P =0.03), female sex (aOR, 1.27 95% CI, 1.08–1.50; P =0.004), and smoking (aOR, 1.20 95% CI, 1.04–1.38; P =0.01) were independently associated with graft failure, whereas statins were associated with a protective effect (aOR, 0.74 95% CI, 0.63–0.88; P <0.001). Graft failure was associated with an increased risk of myocardial infarction or repeat revascularization occurring between CABG and imaging assessment (8.0% in patients with graft failure versus 1.7% in patients without graft failure; aOR, 3.98 95% CI, 3.54–4.47; P <0.001). Graft failure was also associated with an increased risk of myocardial infarction or repeat revascularization occurring after imaging (7.8% versus 2.0%; aOR, 2.59 95% CI, 1.86–3.62; P <0.001). All-cause death after imaging occurred more frequently in patients with graft failure compared with patients without graft failure (11.0% versus 2.1%; aOR, 2.79 95% CI, 2.01–3.89; P <0.001). CONCLUSIONS: In contemporary practice, graft failure remains common among patients undergoing CABG and is strongly associated with adverse cardiac events.