Semaglutide Reduces Major Cardiovascular Events by 20% in SELECT Trial
Written by
Dr. Sarah M. Chen, MD, PhD
Medical Director and Lead Reviewer, Endocrinology
Medically reviewed by
Dr. Marcus T. Webb, MD
Cardiovascular Research Editor
The landmark SELECT trial demonstrated that weekly semaglutide 2.4mg significantly reduced the risk of heart attack, stroke, and cardiovascular death in overweight adults without diabetes, establishing a new standard of care.
Key Findings
- 20% reduction in major adverse cardiovascular events vs. placebo
- 17,604 overweight or obese adults enrolled — largest GLP-1 cardiovascular trial to date
- Benefits observed in patients without diabetes, expanding the eligible population
- Significant reductions in non-fatal heart attack, non-fatal stroke, and cardiovascular death
- Effect was consistent across all pre-specified subgroups including age, sex, and BMI
Background
The SELECT (Semaglutide Effects on Cardiovascular Outcomes in People with Overweight or Obesity) trial was a landmark Phase 3 randomized controlled trial designed to evaluate whether semaglutide 2.4mg weekly could reduce cardiovascular events in adults with established cardiovascular disease who were overweight or obese but did not have diabetes. Prior to SELECT, GLP-1 receptor agonists had demonstrated cardiovascular benefits primarily in patients with type 2 diabetes. SELECT was the first large-scale trial to test this hypothesis in a non-diabetic population.
Study Design
SELECT enrolled 17,604 adults aged 45 or older with a BMI of 27 or higher and established cardiovascular disease (prior heart attack, stroke, or peripheral arterial disease) but without type 2 diabetes. Participants were randomized 1:1 to receive either semaglutide 2.4mg subcutaneously once weekly or placebo, in addition to standard of care. The primary endpoint was a composite of cardiovascular death, non-fatal myocardial infarction, or non-fatal stroke (3-point MACE). The trial ran for a median of 34.2 months.
Primary Results
Semaglutide reduced the primary composite endpoint by 20% compared to placebo (HR 0.80; 95% CI 0.72 to 0.90; p less than 0.001). This translates to a number needed to treat of approximately 67 over 3 years to prevent one major cardiovascular event. The Kaplan-Meier curves began to diverge early and continued to separate throughout the trial, suggesting a durable and progressive benefit.
Secondary Outcomes
Beyond the primary endpoint, semaglutide demonstrated significant reductions across multiple secondary outcomes. Non-fatal myocardial infarction was reduced by 28% (HR 0.72), and non-fatal stroke was reduced by 7% (HR 0.93, not statistically significant individually). All-cause mortality showed a favorable trend. Additionally, participants on semaglutide lost an average of 9.4% of body weight compared to 0.9% in the placebo group, though the cardiovascular benefit appeared to be partially independent of weight loss.
Safety Profile
The safety profile of semaglutide in SELECT was consistent with prior trials. Gastrointestinal adverse events (nausea, vomiting, diarrhea) were more common in the semaglutide group but were generally mild to moderate and decreased over time. Serious adverse events were numerically lower in the semaglutide group. There was no increased risk of pancreatitis, gallbladder disease requiring surgery, or thyroid cancer compared to placebo.
Clinical Implications
SELECT fundamentally changes the landscape of GLP-1 therapy. For the first time, there is robust evidence that semaglutide reduces cardiovascular events in overweight and obese patients without diabetes. This expands the potential eligible population for GLP-1 therapy significantly. Cardiologists, endocrinologists, and primary care physicians should consider semaglutide as part of the cardiovascular risk reduction toolkit for appropriate patients, alongside statins, antihypertensives, and antiplatelet therapy.
What This Means for Patients
If you have a history of heart attack, stroke, or peripheral arterial disease and are overweight or obese, semaglutide may offer meaningful cardiovascular protection beyond what standard medications provide. This is a conversation worth having with your cardiologist or primary care physician. Note that semaglutide requires a prescription and is not appropriate for everyone — your doctor will evaluate your complete medical history before recommending it.
Sources & References
- 1.SELECT Trial Primary Publication: Lincoff AM, et al. Semaglutide and Cardiovascular Outcomes in Obesity without Diabetes. N Engl J Med. 2023;389(24):2221-2232.
- 2.AHA/ACC Cardiovascular Guidelines: Grundy SM, et al. 2018 AHA/ACC Guideline on the Management of Blood Cholesterol. Circulation. 2019;139(25):e1082-e1143.
- 3.FDA Prescribing Information — Semaglutide Injection: U.S. Food and Drug Administration. Semaglutide Injection Prescribing Information. 2023.
Medical Disclaimer: This article is for informational and educational purposes only and does not constitute medical advice. Always consult a licensed healthcare provider before starting, stopping, or changing any medication.