Metformin treatment is associated with improved survival in diabetic patients hospitalized with acute heart failure: A prospective observational study using the Korean acute heart failure registry data

Aims: Although the hypothesis that metformin is beneficial for patients with diabetes and heart failure (HF) has been steadily raised, there is limited data on metformin use in patients with acute HF. We analyzed the association of metformin on all-cause mortality in hospitalized patients with type 2 diabetes and acute HF. Methods: The Korean Acute Heart Failure registry prospectively enrolled patients hospitalized for acute HF from 2011 to 2014. Among this cohort, we analyzed patients with diabetes with baseline estimated glomerular filtration rate (eGFR) of 30 ml/min/1.73 m² or more. We analyzed the all-cause mortality and re-hospitalization for HF within 1 year after discharge. Inverse probability treatment weighting method was used to adjust baseline differences on metformin treatment. Results: The study analyzed data from 1,309 patients with HF and diabetes (mean age 69 years, 56 % male). Among them, 613 (47 %) patients were on metformin at admission. During the median follow-up period of 11 months, 132 (19 %) and 74 (12 %) patients not receiving and receiving metformin treatment died, respectively. The mortality rate was lower in metformin users than in non-users (hazard ratio 0.616 [0.464–0.819] P<0.001). After adjustment, metformin was significantly associated with a lower risk for the mortality (hazard ratio 0.677 [0.495–0.928] P=0.015). In subgroup analyses, this association remains significant irrespective of baseline kidney function (eGFR <60 or ≥60 ml/min/1.73 m², P-for-interaction=0.176) or left ventricular ejection fraction (<40 %, 40–49 %, or ≥50 %, P-for-interaction=0.224). Conclusions: Metformin treatment at the time of admission was associated with a lower risk for 1-year mortality in patients with diabetes, hospitalized for acute HF.