Treatment with the SGLT2 inhibitor empagliflozin led to significant reductions in both left ventricular end systolic and diastolic volumes in two independent randomized studies of patients with heart failure with reduced ejection fraction.
These results provide important new evidence that one way a drug from this class exerts its beneficial effects on cardiovascular outcomes in these patients is by producing favorable left-ventricular remodeling.
One of the two studies involved only patients with heart failure with reduced ejection fraction (HFrEF) with diabetes and examined treatment impact after 36 weeks. The second study focused exclusively on HFrEF patients without diabetes and followed patients for 6 months. Both studies also generated additional significant evidence of favorable left-ventricular effects.
“The results of these two new trials are incredibly important, as they tell cardiologists one of the mechanisms by which SGLT2 [sodium glucose co-transporter 2] inhibitors reduce heart failure hospitalizations and cardiovascular death,” said Mark C. Petrie, MBChB, professor at the Institute of Cardiovascular & Medical Sciences at the University of Glasgow, and principal investigator for one of the two studies.
“Many cardiologists want to know mechanisms as well as clinical benefit. These remodeling data showing that these drugs reduce the size of abnormally large hearts are also very important for patients,” Dr. Petrie said in an interview. “There have been more than 50 publications on potential mechanisms of benefit of SGLT2 inhibitors in HFrEF, but these are the first randomized, mechanistic data.”
Mechanistic Clues Follow Large Cardiovascular Outcome Trials
Results from a large randomized trial, EMPEROR-Reduced, recently showed that treatment with empagliflozin (Jardiance) on top of standard HFrEF treatment led to significant benefits in patients with or without type 2 diabetes (T2D), compared with placebo, for major cardiovascular and renal endpoints, including the combination of cardiovascular death or hospitalization for heart failure. And results from a second large randomized trial, DAPA-HF, showed similar results with a different drug from the same class, dapagliflozin (Farxiga), in an earlier report.
But while these reports led to quick uptake of these two drugs for the treatment of patients with HFrEF, the means by which these agents exert their HFrEF benefits have been unclear.
“Our study identifies why this drug [empagliflozin] is effective – because it improves heart function, something that has not been understood until now,” Carlos G. Santos-Gallego, MD, lead investigator for the second new report, said in a written statement. “Many doctors are afraid of prescribing a drug they do not understand, and our findings will help clinicians feel more comfortable giving this to patients once approved.”
On the strength of the DAPA-HF results, dapagliflozin received a revised U.S. label in May 2020 that added the indication for treating patients with HFrEF regardless of the whether patients also have T2D, the original indication for prescribing the drug. Many experts anticipate that a similar addition to the label for empagliflozin will soon occur.
SUGAR-DM-HF Enrolled Only T2D Patients
The second study, SUGAR-DM-HF, randomized 105 patients with HFrEF and T2D to treatment with empagliflozin or placebo at any of 15 centers in Scotland, with 92 patients completing the full 36 weeks on treatment. One of the study’s two primary endpoints was the change in left ventricular end systolic volume index, which dropped by an average of 7.9 mL/m2 in patients who received empagliflozin and by 1.5 mL/m2 in the controls, a significant average between-group difference of 6.0 mL/m2, reported Matthew M.Y. Lee, MBChB, at the same meeting.
The results also showed a significant drop in left ventricular end diastolic volume index from baseline compared with the control patients, with an average between-group difference in the reduction from baseline of 8.2 mL/m2.
“Reverse cardiac remodeling is a mechanism by which SGLT2 inhibitors reduce heart failure hospitalizations and cardiovascular mortality,” Dr. Lee concluded during his presentation at the meeting.
Although the findings from both studies together provide strong evidence for an effect by empagliflozin on left ventricular shape and function, neither study provides much insight into how this drug exerts these effects. The authors of both studies agreed on several potential explanations, including reductions in cardiac preload and afterload that could reduce left ventricular stretch and volume; a change triggered in myocardial energetics that switches from a metabolism mostly dependent on glucose to one more geared to using fatty acids, ketone bodies, and branched chain amino acids; and a possible drug-induced reduction in oxidative stress and inflammation.
SUGAR-DM-HF was sponsored by a grant from Boehringer Ingelheim, the company that along with Eli Lilly markets empagliflozin (Jardiance). Dr. Lee had no disclosures. Dr. Petrie has been a consultant to Boehringer Ingelheim and Eli Lilly and to several other companies. EMPA-TROPISM was sponsored by a grant from Boehringer Ingelheim. Dr. Badimon and Dr. Santos-Gallego had no disclosures.
This article originally appeared on MDedge.com, part of the Medscape Professional Network.