Metformin therapy and prognosis of patients with heart failure and new-onset diabetes mellitus. A propensity-matched study in the community.
OBJECTIVE
To assess the effect of the commencement of metformin therapy (CMet) on the prognosis of patients with newly diagnosed heart failure (HF) and new-onset diabetes mellitus (DM) treated with a contemporary medical regimen.


METHODS
Prospective study of 1519 HF patients with DM during 9 years. Mean age was 71.7+/-7.8 years, 817 (53.8%) were women, and 780 (51.3%) had preserved systolic function. During a median follow-up of 56.9+/-18.2 months, 1045 patients (68.8%) died, 1344 (88.5%) were hospitalized for worsening HF, 593 (39.0%) did not CMet, and 391 of the patients CMet (42.2%) had a mean HbA1c=<7.0%. No case of lactic acidosis due to metformin was observed. We propensity-score matched 592 patients who CMet with another 592 patients non-CMet.


RESULTS
CMet was associated with a decreased mortality (HR [CI 95%]: .85 [.82-.88]), mainly due to a reduced cardiovascular mortality (HR: .78 [.74-.82]), and with a lower hospitalization rate (HR: .81 [.79-.84]). Nevertheless, CMet was not associated with an improved prognosis of HF patients with a mean HbA1c=<7.0%. These relationships of CMet with prognosis were maintained, independently of the gender, the type of HF (systolic or, non-systolic), the comorbidities, and the medication used (P<.01).


CONCLUSION
Metformin therapy is associated with a reduced mortality of heart failure patients with new-onset diabetes mellitus, mainly due to a decreased cardiovascular mortality, and with a lower hospitalization rate. Nevertheless, CMet was not associated with an improved prognosis of HF patients with a mean HbA1c=<7.0%.