Cardiovascular outcomes associated with treatment of type 2 diabetes in patients with ischaemic heart failure

Aim The optimal strategy for diabetes control in patients with heart failure (HF) following myocardial infarction (MI) remains unknown. Metformin, a guideline-recommended therapy for patients with chronic HF and type 2 diabetes mellitus (T2DM), is associated with reduced mortality and HF hospitalizations. However, worse outcomes have been reported when used at the time of MI. We compared outcomes of patients with T2DM and HF of ischaemic aetiology according to antidiabetic treatment. Methods and results This study used linked data from primary care, hospital admissions, and death registries for 4.7 million inhabitants in England, as part of the CALIBER resource. The primary endpoint was a composite of cardiovascular mortality and HF hospitalization. The secondary endpoints were the individual components of the primary endpoint and all-cause mortality. To evaluate the effect of temporal changes in diabetes treatment, antidiabetic medication was included as time-dependent covariates in survival analyses. The study included 1172 patients with T2DM and prior MI and incident HF between 3 January 1998 and 26 February 2010. Five hundred and ninety-six patients had the primary outcome over median follow-up of 2.53 (IQR: 0.98-4.92) years. Adjusted analyses showed a reduced hazard of the composite endpoint for exposure to all antidiabetic medication with hazard ratios (HRs) of 0.50 [95% confidence interval (CI): 0.42-0.59], 0.66 (95% CI: 0.55-0.80), and 0.53 (95% CI: 0.43-0.65), respectively. A similar effect was seen for all-cause mortality [HRs of 0.43 (95% CI: 0.35-0.52), 0.57 (95% CI: 0.46-0.70), and 0.34 (95% CI: 0.27-0.43), respectively]. Conclusions When considering changes in antidiabetic treatment over time, all drug classes were associated with reduced risk of cardiovascular mortality and HF hospitalization.