In a propensity-score-matched retrospective cohort of 848,538 adults with obesity drawn from the TriNetX platform, tirzepatide was associated with a 10% lower hazard of new-onset heart failure compared with semaglutide (HR 0.90, 95% CI 0.86–0.93), a 20% lower all-cause mortality hazard (HR 0.80, 95% CI 0.77–0.91), and a 20% lower risk of new-onset systolic heart failure. The absolute risk difference for heart failure was modest at −0.3 percentage points over one year. Rates of atrial fibrillation, diastolic heart failure, and hospital encounters were similar between groups.
This is among the largest head-to-head real-world comparisons of these two GLP-1–based agents, and the mortality signal — a 20% relative reduction — is clinically meaningful if it survives scrutiny. Tirzepatide's dual GIP/GLP-1 agonism produces superior weight loss and broader cardiometabolic improvements than semaglutide alone in trials, offering a plausible mechanism. However, this is an observational design: despite careful propensity matching, residual confounding is unavoidable — tirzepatide users may differ systematically in unmeasured ways such as socioeconomic status, adherence, or concurrent medications. The one-year follow-up window is also short for cardiovascular endpoints. Crucially, this is a preprint posted on medRxiv and has not yet been peer-reviewed, so findings and effect sizes may change substantially. Until randomised head-to-head trial data exist, clinicians should treat these as hypothesis-generating, though the consistency across heart failure subtypes and mortality adds credibility.