In people with type 2 diabetes who already had heart failure, tirzepatide was tied to fewer deaths and heart-failure hospital visits than an older diabetes shot, dulaglutide. The gap looks real on paper. The study's own authors say not to bank on it.
The numbers come from an exploratory analysis of SURPASS-CVOT, the large trial that ran Eli Lilly's tirzepatide (sold as Mounjaro and Zepbound) head to head against the company's older drug dulaglutide (Trulicity) in 13,299 people with diabetes and established heart disease across 30 countries, followed for about four years. The heart-failure breakdown was published October 15 in the European Journal of Preventive Cardiology ↗, led by Stephen Nicholls. About one in five patients, 20.3 percent, said they had a history of heart failure when they enrolled.
In that heart-failure group, the combined rate of death or a heart-failure hospitalization or urgent visit was 18.2 percent on tirzepatide and 21.5 percent on dulaglutide. In plain terms, roughly one in six of those events did not happen on the newer drug (hazard ratio 0.83, a 17 percent lower relative risk). A wider measure that counts heart attacks, strokes, cardiovascular death and artery-opening procedures ran lower too (hazard ratio 0.81).
Here is the catch, and the authors lead with it. SURPASS-CVOT was designed to answer a narrower question: whether tirzepatide was not worse than dulaglutide on major heart events. It was a noninferiority trial. The heart-failure edge is the answer to a question the trial never set out to ask, which is why the authors call the analysis hypothesis generating and the differences nominal. The comparisons were not corrected for the fact that many were run at once, so some will look impressive by chance alone.
The signal is also soft at the edges. For the heart-failure group, the confidence interval on that headline number ran from 0.70 to 0.99. The upper end stops one hundredth short of 1.0, the line where a drug does nothing. In the much larger group with no heart-failure history, the same measure came in at hazard ratio 0.88 with an interval of 0.78 to 1.00, touching that line exactly. A result that barely clears the bar in one subgroup and just fails to clear it in the other is a hint, not a verdict.
What makes it worth reporting anyway is the comparator. Almost every GLP-1 headline pits the drug against placebo or against lifestyle changes, which makes the drug look good by default. SURPASS-CVOT is one of the few trials that runs two active drugs against each other, and dulaglutide is not a straw man. It carries its own heart-protection label from the REWIND trial. Beating a drug that already works is a higher bar than beating a sugar pill.
The mechanism is the plausible reason for a gap. Dulaglutide activates one gut-hormone receptor, GLP-1. Tirzepatide activates two, adding GIP, and it drives more weight loss and tighter glucose control than single-receptor drugs in head-to-head testing. Whether that translates into fewer heart-failure events, as opposed to simply fewer pounds and better sugar numbers, is exactly what this analysis cannot prove. Heart-failure status here was self-reported, and the trial collected no cardiac imaging or natriuretic-peptide blood tests, so it cannot separate the two forms of heart failure (stiff-but-pumping versus weak-pumping) that respond differently to almost everything.
On peptidemodel, both drugs sit on the same shelf and split on exactly this receptor count. Tirzepatide ↗ is tagged to both GLP-1R ↗ and GIPR ↗; dulaglutide ↗ carries GLP-1R alone. A real-world ranking of five GLP-1 shots that put tirzepatide first ↗ pointed the same direction from messier data. A proper trial, powered for heart failure and built to measure it, would settle whether the dual-receptor drug actually protects the heart or just happens to be the stronger metabolic drug. This one was not that trial.