Tirzepatide Cardiovascular Outcomes: The SURPASS-CVOT Trial

Cardiovascular outcomes trials (CVOTs) became a regulatory expectation for new diabetes therapies after the rosiglitazone controversies of the late 2000s. Today, no GLP-1 receptor agonist or related peptide reaches widespread clinical use without dedicated cardiovascular safety and efficacy data. In December 2025, the New England Journal of Medicine published SURPASS-CVOT, the cardiovascular outcomes trial that compared tirzepatide directly with dulaglutide in patients with type 2 diabetes and established atherosclerotic cardiovascular disease (ASCVD).

Why Compare Tirzepatide to Dulaglutide?

Most CVOTs compare a new drug to placebo. SURPASS-CVOT did something different: it tested tirzepatide head-to-head against an established active comparator — dulaglutide, a once-weekly GLP-1 RA with proven cardiovascular benefit from the REWIND trial. The choice of active comparator was deliberate and ethical: in a population with established ASCVD, leaving patients on placebo for years would have been difficult to justify when an evidence-based GLP-1 therapy was available.

This design changes the interpretive framework. Rather than asking "does tirzepatide reduce MACE versus placebo?" — which would be largely expected based on its mechanism — SURPASS-CVOT asked: "is tirzepatide at least as good as the established standard, and might it be better?"

Trial Design and Population

SURPASS-CVOT enrolled adults with type 2 diabetes plus established atherosclerotic cardiovascular disease — including prior myocardial infarction, ischemic stroke, peripheral artery disease, or coronary revascularization. Participants were randomized to weekly tirzepatide (titrated to maximum tolerated dose) or weekly dulaglutide 1.5 mg, with median follow-up of approximately 4 years. The primary outcome was the composite of cardiovascular death, nonfatal myocardial infarction, or nonfatal stroke (the standard MACE composite).

Primary Outcome

Key Secondary Outcomes

Interpretation: Noninferior, Not Superior

How should the noninferior-but-not-superior MACE result be interpreted?

• For patients with established ASCVD, tirzepatide and dulaglutide appear roughly equivalent for preventing major cardiovascular events. The choice between them may now hinge more on weight management goals, glycemic targets, side effect profile, and cost.
• For patients prioritizing weight reduction or aggressive glycemic control, tirzepatide's clear advantages on these endpoints are now anchored by reassuring cardiovascular safety data.
• The inability to demonstrate MACE superiority reflects the high bar set by an active comparator with proven cardiovascular benefit. It does not mean tirzepatide lacks cardiovascular protection — only that it is not measurably better than dulaglutide for this specific endpoint.

Implications for the Field

SURPASS-CVOT settles tirzepatide's place in the cardiovascular conversation. Practical implications:

• Cardiovascular safety is no longer a barrier to tirzepatide use in patients with ASCVD.
• Tirzepatide can be considered for patients with diabetes plus ASCVD where greater weight reduction or glycemic improvement is clinically important.
• Future trials will likely test tirzepatide against placebo in ASCVD patients without diabetes (parallel to the SELECT trial for semaglutide), which may eventually produce additional indication expansion.

Adverse Events

The safety profile in SURPASS-CVOT was consistent with prior tirzepatide experience: gastrointestinal adverse events (nausea, diarrhea, vomiting, constipation) were most common during dose escalation. The trial did not raise new cardiovascular safety concerns. The boxed warning for thyroid C-cell tumors and contraindications in personal or family history of medullary thyroid carcinoma and MEN2 syndrome remain.

What This Means at Irvine Health

For patients evaluating tirzepatide who have a history of cardiovascular disease, SURPASS-CVOT provides reassuring evidence that this dual GIP/GLP-1 agonist does not increase cardiovascular risk relative to an established comparator with proven cardiovascular benefit. As with all peptide therapy decisions at our practice, the choice between semaglutide, tirzepatide, or other agents involves a thorough physician evaluation of cardiovascular history, weight management goals, glycemic status, and individual risk factors.