What percentage did semaglutide reduce MACE risk in the SELECT trial?

What exactly did the SELECT trial measure, and who took part?

SELECT stands for Semaglutide Effects on Heart Disease and Stroke in Patients with Overweight or Obesity. The trial recruited 17,604 adults, all of whom had a documented history of cardiovascular disease (previous heart attack, stroke or symptomatic peripheral artery disease) and a BMI of 27 or above. Crucially, none had type 2 diabetes. That exclusion matters: it separated the cardiovascular question from any glucose-lowering effect, which had already explained heart benefits seen in earlier diabetes trials.

Participants received weekly subcutaneous injections of semaglutide 2.4mg or placebo, alongside standard care, for a median follow-up of around 39 months. The primary endpoint was time to first MACE event. Novo Nordisk published the results in the New England Journal of Medicine, and you can read the STEP 1 trial paper on the NEJM website for the weight-loss side of the same medicine's data; the SELECT cardiovascular paper followed in the same journal in 2023.

A quick practical check: if you want to confirm semaglutide's current UK authorisations in one place, the MHRA Products register or the electronic Medicines Compendium (eMC) lists Wegovy's full Summary of Product Characteristics, including the cardiovascular indication, and takes under a minute to search.

What does a 20% relative risk reduction actually mean in practice?

Risk reduction percentages in clinical trials are relative figures, which means they describe the proportional difference between two groups rather than the absolute number of events prevented. In SELECT, the MACE rate was roughly 6.5% in the placebo group versus around 5.3% in the semaglutide group over the trial period, a difference of approximately 1.3 percentage points. Expressed relatively, that is the 20% figure widely reported.

That absolute difference may sound modest, but across a high-risk population of nearly 18,000 people followed for three-plus years, it translated to a meaningful number of cardiovascular events avoided. Cardiologists regard a 20% relative risk reduction in MACE as clinically significant: comparable trials with statins, for reference, reported reductions in a similar range in secondary-prevention populations.

Each individual component of the MACE composite was also reduced, not just the combined endpoint. Cardiovascular death, non-fatal heart attack and non-fatal stroke all moved in the same direction, which strengthens confidence that the result reflects a genuine pharmacological effect rather than a statistical artefact. Our semaglutide overview page sets out how the medicine works and what the UK licences cover.

Did the heart benefit come from weight loss, or something else?

This is a question our clinical team hears regularly, and the honest answer is: probably both, and the evidence leans toward direct cardiovascular mechanisms beyond weight loss alone.

In pre-specified analyses, the 20% MACE reduction appeared relatively consistent across subgroups defined by how much weight participants lost, including those who lost less than 5% of their body weight. That pattern suggests semaglutide's cardiovascular effect is not purely mediated through adipose tissue reduction. Proposed mechanisms include improvements in blood pressure, lipid profiles, inflammatory markers and direct effects on the cardiovascular system via GLP-1 receptors expressed in cardiac tissue.

The medicine's anti-inflammatory properties have attracted separate research interest. Semaglutide reduces levels of high-sensitivity C-reactive protein (hsCRP), a marker of systemic inflammation linked to cardiovascular risk. You can explore that evidence on our page about semaglutide's effects on inflammatory markers. Similarly, reductions in visceral fat, which sits around abdominal organs and drives metabolic harm independently of overall body weight, are detailed on our visceral fat reduction page.

For the purposes of the SELECT cardiovascular licence, weight loss is not a requirement for the indication: a prescriber would assess the cardiovascular risk profile separately from any weight-management need.

How does the SELECT finding change what semaglutide is licensed for in the UK?

Before SELECT, Wegovy held a single UK licence: weight management in adults with a BMI of 30 or above, or 27 or above with at least one weight-related condition. The SELECT data prompted Novo Nordisk to seek, and the MHRA to grant, a separate authorisation for reducing the risk of serious cardiovascular events in adults with established cardiovascular disease and either overweight or obesity.

This is a meaningful regulatory distinction. It means semaglutide can now be clinically indicated for a person whose primary concern is cardiovascular risk, irrespective of how much weight they need to lose. The MHRA's approval of this indication, along with more recent decisions on MASH (a form of fatty liver disease), reflects a broadening picture of semaglutide's therapeutic profile. Our page on semaglutide and MASH covers the liver indication in detail.

In practice, the cardiovascular indication is prescribed and managed by cardiologists and specialist physicians rather than through a weight-management pathway. Semaglutide for weight management remains a prescription-only medicine requiring clinical assessment, whether accessed through the NHS or privately. If you are already on semaglutide for weight management and have cardiovascular disease, the two clinical pathways can overlap, but the prescriber's view governs. You can read a broader overview of the SELECT trial and Wegovy's cardiovascular authorisation on our dedicated page, or explore Wegovy's full profile including its weight-management evidence.

If you are considering semaglutide through a private route and want to understand whether it is clinically appropriate for your situation, a free consultation with one of our GPhC-registered prescribers is the right starting point. Start your free consultation and a prescriber will review your answers the same day.