Objective: Diabetes mellitus (DM) is a very important prognostic factor in patients with coronary artery disease. The precise effects of controlled or uncontrolled diabetes on bypass graft patency in the long term have not yet been determined. The aim of this study was to assess the effect of the glycated hemoglobin (HbA1c) level on bypass graft patency and contribute information about HbA1c targets for patients with diabetes and a history of bypass surgery.
Materials and Methods: A total of 606 patients who underwent coronary bypass surgery and coronary angiography were evaluated. Grafts with any stenosis not causing flow restriction were accepted as patent. The average of all available HbA1c measurements within a year of the angiography was used for analysis. Patients were also analyzed according to the average HbA1c level: well-controlled DM was defined as an average HbA1c level of <7% and uncontrolled DM was defined at an HbA1c level of ≥7%.
Results: In all, 114 patients were included in the study, yielding a total of 289 grafts (venous: 182, arterial: 107). The median HbA1c value of the study population was 7.5 mg/dL. The occlusion rate of arterial and venous grafts was 12.4% and 28.2%, respectively. The median graft age was 8.0 years. The HbA1c level was similar in arterial and saphenous grafts according to the presence or absence of occlusion.
Conclusion: The HbA1c level was not associated with long-term coronary bypass graft patency. Only a graft age of >5 years was significantly associated with long-term venous graft patency. Studies with patients whose HbA1c level is more strictly controlled may reveal different results.