Lessons learned from the DAPA-HF trial concerning the mechanisms of benefit of SGLT2 inhibitors on heart failure events in the context of other large-scale trials nearing completion

Four large-scale trials in type 2 diabetes have shown that sodium-glucose cotransporter 2 (SGLT2) inhibitors prevent the occurrence of serious heart failure events. Additionally, the DAPA-HF trial demonstrated a benefit of dapagliflozin to reduce major adverse outcomes in patients with established heart failure with a reduced ejection fraction. The trial sheds light on potential mechanisms. In DAPA-HF, the benefits of dapagliflozin on heart failure were seen to a similar extent in both patients with or without diabetes, thus undermining the hypothesis that these drugs mitigate glycemia-related cardiotoxicity. The action of SGLT2 inhibitors to promote ketogenesis is also primarily a feature of the action of these drugs in patients with diabetes, raising doubts that enhanced ketogenesis contributes to the benefit on heart failure. Also, dapagliflozin does not have a meaningful effect to decrease circulating natriuretic peptides, and it did not potentiate the actions of diuretics in DAPA-HF; moreover, intensification of diuretics therapy does not reduce cardiovascular death, questioning a benefit of SGLT2 inhibitors that is mediated by an action on renal sodium excretion. Finally, although hematocrit increases with SGLT2 inhibitors might favorably affect patients with coronary artery disease, in DAPA-HF, the benefit of dapagliflozin was similar in patients with or without an ischemic cardiomyopathy; furthermore, increases in hematocrit do not favorably affect the clinical course of patients with heart failure. Therefore, the results of DAPA-HF do not support many currently-held hypotheses about the mechanism of action of SGLT2 inhibitors in heart failure. Ongoing trials are likely to provide further insights.