Underuse of evidence-based treatment partly explains the worse clinical outcome in diabetic patients with acute coronary syndromes

Background: Diabetes-related differences in treatment and clinical outcome of patients across the entire spectrum of acute coronary syndromes (ACSs) have potential clinical implications but have not been well studied. Methods: The multicenter, prospective, Canadian ACS Registry enrolled 4578 patients hospitalized for ACS between 1999 and 2001 across 9 provinces in Canada. We compared baseline characteristics, in-hospital and post-discharge treatments, and clinical outcome of diabetic and non-diabetic patients. The impact of diabetes on use of thrombolytic therapy and coronary revascularization; and the independent association between diabetes, treatments, and diabetes-treatment interactions on outcome were examined. Results: Diabetic patients with ACS had more cardiovascular risk factors and higher-risk clinical presentation. They paradoxically received less evidence-based medications in-hospital, at discharge, and at 1-year. Although diabetes independently predicted higher 1-year mortality (OR 1.47, 95% CI 1.15-1.87; P = .002) after adjustment for validated prognosticators, it was also an independent predictor of not receiving thrombolytic therapy (OR 0.72, 95% CI 0.54-0.95; P = .021) and coronary revascularization (OR 0.69, 95% CI 0.59-0.82; P < .001). These underused therapies were all independently associated with reduced 1-year mortality, with no significant diabetes-related treatment-outcome heterogeneity. Importantly, diabetes remained an independent adverse prognosticator even after further adjustment for these differences in treatment. Conclusions: Evidence-based therapies are underused in the contemporary management of diabetic patients with ACS, which partly explains their worse outcome. Diabetes should be considered a high-risk feature in ACS risk stratification that encourages more intensive treatments. Continued efforts to promote adherence to existing proven therapies and to develop novel treatment strategies targeting diabetes-specific cardiovascular pathophysiology are imperative to improve their adverse prognosis.