GLP-1 Heart Health Benefits: What the SELECT Trial Really Showed

Most people start a GLP-1 medication to lose weight. What they do not always realise is that one of these drugs — semaglutide 2.4mg (Wegovy) — has now demonstrated something rarer in medicine: a statistically significant reduction in major cardiovascular events, independent of weight loss alone.

That finding comes from the SELECT trial, published in the New England Journal of Medicine in 2023. It is one of the most clinically important results in obesity medicine in the past decade, and it changes how cardiologists and GPs should be thinking about Wegovy for certain patients.

What SELECT Actually Measured

The SELECT (Semaglutide Effects on Cardiovascular Outcomes in People with Overweight or Obesity) trial enrolled 17,604 adults who had established cardiovascular disease — meaning they had already had a heart attack, stroke, or had peripheral arterial disease — but did not have type 2 diabetes. Participants had a BMI of 27 or above.

They were randomised to either semaglutide 2.4mg weekly or placebo, and followed for an average of around 33 months (just under three years).

The primary outcome was a composite of three major adverse cardiovascular events: cardiovascular death, non-fatal heart attack, and non-fatal stroke — known as MACE.

The result was a 20% relative risk reduction in MACE. That translates to a number needed to treat (NNT) of 67 — meaning for every 67 patients treated with Wegovy for around 33 months, one additional major cardiovascular event is prevented compared to placebo.

For context, that is comparable to or better than many statins in high-risk primary prevention populations.

Why the Result Is More Than Weight Loss

The investigators did something important: they tried to separate the cardiovascular benefit from the weight loss effect. When they statistically adjusted for the degree of weight lost, the cardiovascular benefit remained. This suggests the mechanism is at least partially independent of weight.

What does that mean biologically? Several mechanisms have been proposed:

Inflammation. GLP-1 receptors are expressed in the heart and blood vessels. Semaglutide appears to reduce inflammatory markers including high-sensitivity CRP, which drives atherosclerotic plaque instability.

Blood pressure. Across the STEP trials, semaglutide consistently lowered systolic blood pressure by 4-6 mmHg. Even modest reductions in blood pressure have compounding cardiovascular benefit over years.

Lipids. Participants in SELECT showed improvements in LDL cholesterol and triglycerides that were partially but not fully explained by weight loss.

Cardiac fat. Epicardial and pericardial fat — the deposits around the heart that are metabolically active and pro-inflammatory — decrease significantly on semaglutide. A small but growing body of imaging data suggests this may matter for arrhythmia risk and heart failure.

None of these mechanisms alone explains the magnitude of the effect. The current view is that it is a combination.

What This Means for UK Prescribing

The MHRA and NHS England have both taken note. The cardiovascular indication for Wegovy was a significant factor in the NHS England decision to expand access beyond the original weight management pathway, particularly for patients with established CVD. You can read more about that expansion at /guides/nhs-wegovy-cardiovascular-expansion.

In practical terms, UK GPs and cardiologists can now consider Wegovy for patients who have had a heart attack or stroke and have a BMI over 27, even if weight loss is not the primary goal. NICE guidance is evolving to reflect this — as of 2026, the cardiovascular risk reduction pathway is increasingly being used to justify prescriptions.

What About Mounjaro (Tirzepatide)?

This is where honest communication matters. As of May 2026, tirzepatide (Mounjaro) does not have a completed cardiovascular outcomes trial showing MACE reduction.

SURPASS-CVOT — the large-scale trial designed to answer this question for tirzepatide — is underway, but the results have not yet been published. It is entirely plausible that tirzepatide will show similar or even greater cardiovascular benefit given its dual GIP/GLP-1 mechanism and its more pronounced effects on weight, insulin resistance, and lipids. But "plausible" is not evidence.

This distinction matters clinically. If a patient has established CVD and needs a GLP-1, the current evidence base points to semaglutide 2.4mg as the only drug with proven cardiovascular outcome data. Mounjaro may well join it — but that remains to be shown.

Heart Failure: An Emerging Story

Beyond MACE, the SELECT trial and subsequent analyses have pointed to a significant benefit in heart failure with preserved ejection fraction (HFpEF). This is a condition where the heart muscle is stiff and does not relax properly — it is common in people with obesity, and until recently had very few effective treatments.

Sub-analyses of SELECT and data from the STEP-HFpEF trial have shown reductions in symptoms, exercise capacity, and inflammatory markers in HFpEF patients. The STEP-HFpEF trial (published 2023, NEJM) showed a 16-point improvement in the Kansas City Cardiomyopathy Questionnaire (KCCQ) score — a major clinically meaningful change in quality of life for a condition that previously had limited pharmacological options.

This is driving real change in UK cardiology practice. Some heart failure clinics are now initiating Wegovy or discussing it with eligible patients who would previously have been told there was nothing more to offer.

Atrial Fibrillation

A further emerging signal from SELECT and pooled trial data is a reduction in new-onset atrial fibrillation (AF) in patients on semaglutide. The mechanism is thought to involve reduction in epicardial fat and inflammation, both of which are drivers of atrial remodelling and AF.

The evidence is not yet strong enough to list AF prevention as an indication, but it is consistent enough that cardiologists treating obese patients with paroxysmal AF are increasingly mentioning semaglutide as part of the wider management conversation.

Who Should Be Having This Conversation With Their Doctor?

The SELECT trial enrolled a specific population. Before interpreting the results too broadly, here is who this evidence applies to most directly:

• Adults with a BMI of 27 or above
• With established cardiovascular disease (prior MI, stroke, or peripheral arterial disease)
• Without type 2 diabetes
• Who can tolerate semaglutide

Outside this population — for example, primary prevention in someone without established CVD — the cardiovascular evidence is less direct. Weight loss itself has cardiovascular benefits, and the general STEP trial data suggests improvements in risk factors across the board. But the SELECT-level certainty only applies to the secondary prevention population described above.

Getting Access to Wegovy in the UK

Wegovy is available via the NHS through specific pathways, or privately through registered online clinics. If cardiovascular risk reduction is part of the clinical rationale for starting Wegovy, it is worth raising this directly with your prescriber — the cardiovascular indication can affect both eligibility and funding decisions.

For a comparison of UK prescribing options, see /guides/best-glp1-prescriber-uk-2026. For the specific NHS cardiovascular expansion pathway, see /guides/nhs-wegovy-cardiovascular-expansion.

If you want a reputable UK online pharmacy to discuss Wegovy access, Pharmacy2U operates a regulated weight management service where GPs assess eligibility and can factor in cardiovascular history.

The Bottom Line

SELECT changed the clinical landscape for Wegovy. A 20% reduction in MACE — cardiovascular death, heart attack, and stroke — in a high-risk population of nearly 18,000 patients is a result that belongs on the same level of evidence as the landmark statin and antihypertensive trials that reshaped cardiology.

The cardiovascular benefit appears to be at least partially independent of weight loss. The mechanisms are multiple and still being characterised. Mounjaro may produce a similar result when SURPASS-CVOT reports, but that evidence does not exist yet.

For UK patients with established CVD and overweight or obesity, Wegovy is now a drug with cardiovascular outcome data — not just a weight loss medication. That distinction matters, and it should be part of the conversation with any prescriber managing your cardiovascular risk.

For further reading on long-term safety of GLP-1 medications, see /guides/glp1-long-term-use-uk.