Summary: In a prespecified analysis of the SUMMIT trial in obese heart failure with preserved ejection fraction, tirzepatide reduced cardiovascular death or worsening heart failure and improved symptoms to a similar degree whether or not patients had type 2 diabetes, despite less weight loss in those with diabetes.
PICO Summary
| Element | Detail |
|---|---|
| Population | 731 patients with HFpEF and BMI ≥30, with or without type 2 diabetes (diabetes a randomisation stratifier); SUMMIT trial. |
| Intervention | Tirzepatide up to 15 mg subcutaneously weekly for a median of 104 weeks. |
| Comparison | Placebo, with outcomes stratified by baseline diabetes status. |
| Outcome | Cardiovascular death or worsening heart failure fell with tirzepatide (HR 0.62; 95% CI 0.41–0.95; p=0.026), consistent in diabetes (HR 0.64) and without (HR 0.61; interaction p=0.95). Gains in KCCQ score, 6-minute walk, quality of life, and NYHA class were similar by diabetes status. Weight loss was less with diabetes (10.4% vs 12.9%; p=0.04), but reductions in paracardiac fat and left ventricular mass were comparable. |
Tirzepatide in HFpEF by diabetes status
SUMMIT subanalysis · obese HFpEF · 104 weeks
Tirzepatide cut cardiovascular death or worsening heart failure by about 38% in obese HFpEF, with the same benefit whether or not patients had type 2 diabetes, despite less weight loss in those with diabetes.
Expert Commentary
This is an important analysis of a landmark trial, and its conceptual payoff is larger than a routine subgroup check. HFpEF with obesity has been one of the most therapeutically barren areas in cardiology, so the parent SUMMIT result, a clear reduction in cardiovascular death or worsening heart failure with tirzepatide, already mattered. What this stratified analysis adds is reassurance and insight: patients with diabetes, who typically have more advanced disease and often blunted responses, derived the same clinical benefit as those without, with no interaction. The most thought-provoking detail is that diabetic patients lost less weight yet achieved equivalent reductions in visceral and paracardiac fat and in left ventricular mass, hinting that the heart-failure benefit is driven by metabolic and structural cardiac remodelling rather than the number on the scale. The honest caveats are real: this is a prespecified subgroup analysis within a single trial, enriched for obesity, so it does not extend to non-obese HFpEF. Can I use this with my patients? Increasingly yes. For an obese patient with HFpEF, it supports considering tirzepatide irrespective of diabetes status, alongside SGLT2 inhibitors and standard care, while I let evolving guidelines and the full trial define formal indications.
References
Packer M, Zile MR, Kramer CM, et al. Influence of type 2 diabetes on the effects of tirzepatide in patients with heart failure and a preserved ejection fraction with obesity: a prespecified stratification-based analysis. J Am Coll Cardiol. 2025;86(10):696–707. doi:10.1016/j.jacc.2025.06.058