The short answer
In people with obesity and a particular form of heart failure, tirzepatide reduced a combined cardiovascular outcome and improved reported health status versus placebo.
Who was studied?
SUMMIT randomized 731 people with obesity and heart failure with preserved ejection fraction. Median follow-up was 104 weeks.
Percent of participants; median follow-up 104 weeks
Original chart based on the study. Values are reported group results.
| Group or measure | Result |
|---|---|
| Tirzepatide | 9.9% |
| Placebo | 15.3% |
What changed?
Cardiovascular death or worsening heart failure occurred in 9.9% with tirzepatide and 15.3% with placebo.
The difference was mainly in worsening heart-failure events. Cardiovascular deaths alone were few—eight versus five—and the trial did not establish a reduction in cardiovascular death alone.
At 52 weeks, participants receiving tirzepatide reported greater improvement in symptoms and physical limitations on a heart-failure questionnaire.
Adverse events, mainly digestive, caused treatment discontinuation in 6.3% versus 1.4%.
The useful takeaway
This is evidence about living with obesity and established heart failure, not a general claim that tirzepatide prevents heart disease in everyone. The combined outcome and its separate components tell different stories.
Sources
Packer and colleagues, New England Journal of Medicine, 2025. Funded by Eli Lilly. Read the study.