Summary: In a prespecified analysis of the SELECT trial, semaglutide reduced major cardiovascular events consistently across all baseline adiposity categories, and the benefit was largely independent of weight loss, with only about 33% mediated through waist-circumference reduction, suggesting cardioprotective mechanisms beyond fat loss.
PICO Summary
| Element | Detail |
|---|---|
| Population | 17,604 patients aged ≥45 with BMI ≥27 and established cardiovascular disease, without diabetes (804 sites, 41 countries). |
| Intervention | Once-weekly semaglutide 2.4 mg. |
| Comparison | Placebo once weekly (1:1). |
| Outcome | MACE reduction consistent across baseline adiposity. In the semaglutide arm, 4% lower MACE risk per 5 kg lower baseline weight (HR 0.96; 95% CI 0.94–0.99; p=0.001) and per 5 cm smaller waist (HR 0.96; 0.93–0.99; p=0.004). No linear link between week-20 weight loss and later MACE; greater waist reduction was associated with lower MACE. About 33% of benefit mediated by waist reduction (HR 0.86; 0.77–0.97 after adjustment). |
SELECT: CV benefit vs weight loss
Prespecified RCT analysis · overweight/obese CVD, no diabetes
Semaglutide's MACE reduction held across every baseline adiposity stratum and was largely independent of weight loss, with only about a third mediated by waist reduction, pointing to weight-independent cardioprotection.
Expert Commentary
This is one of the more conceptually important sub-analyses of recent years, because it interrogates a comfortable assumption, that semaglutide protects the heart by causing weight loss, and finds it largely wrong. The cardioprotection was consistent across every baseline adiposity stratum and, strikingly, the magnitude of weight loss did not predict the size of the MACE reduction, with only about a third mediated through waist change. That points to weight-independent mechanisms, plausibly anti-inflammatory and direct vascular effects, and it reframes how I explain these drugs. I hold the usual caution that mediation analysis cannot prove causation, and the paradoxical placebo-group signal where weight loss tracked with more events almost certainly reflects illness-driven weight loss confounding. Can I use this with my patients? Yes, and usefully. I can reassure an eligible patient with cardiovascular disease that semaglutide’s heart benefit does not depend on dramatic weight loss, which helps the patient who loses only modestly and might otherwise feel they have failed. It also argues against assuming other weight-loss routes deliver equivalent cardiovascular protection without their own outcome trials.
References
Deanfield J, Lincoff AM, Kahn SE, et al. Semaglutide and cardiovascular outcomes by baseline and changes in adiposity measurements: a prespecified analysis of the SELECT trial. Lancet. 2025;406(10516):2257–2268. doi:10.1016/S0140-6736(25)01375-3