Effect of preoperative diabetic treatment on long-term cardiovascular outcomes in diabetic patients undergoing coronary revascularization therapy

Abstract

Background: The effect of preoperative diabetic treatment, especially insulin therapy, on adverse cardiovascular outcomes in diabetic patients undergoing coronary revascularization therapy has been still debated in the drug-eluting-stent era. Purpose: The present study aimed to evaluate the association between preoperative diabetic treatment and cardiovascular outcomes in patients with diabetes mellitus (DM) after their first coronary revascularization therapy. Methods: During 2005-2007, 15939 patients undergoing first PCI or CABG at 26 hospitals in Japan were enrolled in CREDO-Kyoto PCI/CABG registry cohort-2. This study comprised 10178 patients whose HbA1c values at index hospitalization were available: 5332 patients without DM (non-DM) and 4846 patients with DM. Of the DM patients, 1120 patients were treated with insulin (ITx) and 2591 patients with oral hypoglycemic agents (OTx). Remaining 1135 patients were managed without any glycemic lowering medication: 488 patients with 6.5%≤HbA1c≤6.8% (LG) and 647 with HbA1c≥6.9% (HG). The main outcome measure was major adverse cardiovascular events (MACE: a composite of cardiovascular death, myocardial infarction and stroke). Results: The 3-year survivals free from MACE were 89.2% in non-DM (reference), 81.6% in ITx (log rank p<0.0001), 87.9% in OTx (p=0.14), 88.9% in LG (p=0.80) and 84.5% in HG (p<0.0001). Multivariate Cox proportional hazard models using non-DM as a reference revealed that ITx, OTx and HG had significantly increased risks of MACE. The adjusted risk of MACE was not significantly different between LG and non-DM: hazard ratio (HR) vs. non-DM 1.11, 95% CI 0.82-1.48, p=0.49. Other independent predictors of MACE included anemia, high age, low body mass index, ST-elevation myocardial infarction, multivessel coronary disease, left main trunk disease, atrial fibrillation, peripheral artery disease, chronic kidney disease, history of heart failure and stroke, and no prescription for statin, aspirin, ACE inhibitors/ARB, calcium channel blockers and nitrates. Multivariate models among the DM patients using LG as a reference demonstrated that ITx and HG, but not OTx, were significantly associated with increased risks of MACE (ITx: HR 1.41, 95% CI 1.03-1.97, p=0.03; OTx: HR 1.08, 95% CI 0.80-1.48, p=0.61, HG: HR 1.49, 95% CI 1.06-2.12, p=0.02). Conclusions: In patients with DM undergoing their first coronary revascularization, those with insulin therapy and those without any glycemic lowering medication with HbAlc ≥6.9% had increased risks of major adverse cardiovascular events.