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A Study of Tirzepatide in Participants With Heart Failure With Preserved Ejection Fraction and Obesity (SUMMIT) — VialBase Research

Trial Summary

SUMMIT was a pivotal Phase 3 trial evaluating tirzepatide (dual GIP/GLP-1 receptor agonist) in patients with HFpEF and obesity. HFpEF with obesity is a phenotype driven by metabolic dysfunction, adipose inflammation, and excess volume loading, making it a strong biological fit for incretin-based therapy.

Design

  • Type: Randomized, double-blind, placebo-controlled, multicenter
  • Population: 731 adults with HFpEF (EF 50%+) and BMI 30+
  • Arms: Tirzepatide 15 mg SC weekly vs. placebo
  • Duration: 52 weeks
  • Co-primary endpoints: (1) Composite of CV death or worsening HF events; (2) Change in Kansas City Cardiomyopathy Questionnaire Clinical Summary Score (KCCQ-CSS)

Key Outcomes

  • Both co-primary endpoints met (reported late 2024)
  • 38% reduction in composite of CV death or worsening HF (HR 0.62, p=0.026)
  • Significant improvement in KCCQ-CSS (health status/symptoms) vs. placebo
  • Mean weight loss ~13% with tirzepatide
  • Improvements in 6-minute walk distance, NT-proBNP, CRP
  • Well tolerated; GI side effects consistent with GLP-1 class

Significance for Peptide Research

SUMMIT is a breakthrough for the obesity-HFpEF phenotype, which has historically lacked targeted therapy. The results establish tirzepatide as the first agent to meaningfully reduce HF events in this population. This validates the concept that treating the metabolic root cause of HFpEF (adiposity, inflammation, insulin resistance) can improve hard cardiac outcomes. Directly relevant to incretin-based cardiac therapeutics.

See Also