Cardiovascular promise requires endpoint discipline: interpreting tirzepatide after SURPASS-CVOT

Plain language summary Tirzepatide is a medicine used to treat type 2 diabetes and obesity. It improves blood sugar, supports substantial weight loss and may benefit heart health. However, different studies have examined different groups of patients and measured different outcomes. Their findings should therefore not be treated as interchangeable. In the SURPASS-CVOT study, tirzepatide was compared with dulaglutide, another diabetes medicine already known to provide cardiovascular benefit. Tirzepatide was not worse than dulaglutide in relation to cardiovascular death, heart attack or stroke, but it was not shown to be better. Because the study did not compare tirzepatide with a placebo or usual care, it cannot directly show how much additional cardiovascular benefit tirzepatide provides over no active treatment. A separate study, SUMMIT, found that tirzepatide benefited people with obesity-related heart failure in which the heart’s pumping strength is preserved. The improvement was mainly related to fewer episodes of worsening heart failure rather than fewer cardiovascular deaths. We propose that future discussions of tirzepatide should clearly explain which treatment it was compared with, which outcomes were measured, which patients were studied, how long benefits lasted and whether treatment is affordable. This approach may help patients, clinicians and health systems interpret the evidence accurately and avoid extending findings beyond the groups and outcomes actually studied.