Wegovy Cardiovascular Benefit: 20% Lower MACE Risk (SELECT)

What SELECT actually measured

SELECT enrolled 17,604 adults aged 45 or older who had established cardiovascular disease and a BMI of 27 or higher, with no history of diabetes. Half received semaglutide 2.4 mg once weekly and half placebo, and the mean follow-up was 39.8 months [1].

The primary endpoint was the first occurrence of cardiovascular death, non-fatal myocardial infarction or non-fatal stroke, a three-part composite rather than a single outcome [1]. A primary event occurred in 569 of 8,803 people on semaglutide (6.5%) and 701 of 8,801 on placebo (8.0%), giving a hazard ratio of 0.80 [1].

The 20% reduction applies to the combined outcome, not to each type of cardiovascular event separately.

What the 20% figure means in real numbers

The 20% is a relative reduction. The absolute gap between groups was 1.5 percentage points (6.5% versus 8.0%), which works out to roughly one fewer event per 67 people in these trial groups. That figure is an approximation from the reported percentages, not a separately reported trial endpoint [1].

For context on tolerability, 16.6% of people assigned semaglutide and 8.2% of those assigned placebo stopped treatment because of an adverse event in SELECT [1].

Which part of the composite moved

The Wegovy label's SELECT table separates the components [2]:

• Cardiovascular death: 2.5% versus 3.0% (HR 0.85, 95% CI 0.71 to 1.01). The label says superiority for this component was not confirmed in the testing hierarchy.
• All-cause death: 4.3% versus 5.2% (HR 0.81).
• Fatal or non-fatal myocardial infarction: 2.8% versus 3.8% (HR 0.72).
• Stroke: HR 0.89 (95% CI 0.72 to 1.11).

So the accurate statement is that Wegovy reduced the composite. It is not accurate to say the trial proved Wegovy cuts cardiovascular deaths, because the confidence interval for that component crossed 1.0 [2].

By week 104, mean body weight fell 9.4% with Wegovy versus 0.9% with placebo [2].

Who the evidence covers

The Wegovy label indication reads: to reduce the risk of major adverse cardiovascular events (cardiovascular death, non-fatal myocardial infarction or non-fatal stroke) in adults with established cardiovascular disease and either obesity or overweight, alongside a reduced-calorie diet and more physical activity [2]. The same indication appears for Wegovy tablets [2]. The indication wording does not mention diabetes [2], although SELECT itself enrolled only people without diabetes [1].

The recommended dose for cardiovascular risk reduction is 2.4 mg weekly, or 1.7 mg [2].

SELECT enrolled people who already had cardiovascular disease. It did not test Wegovy for preventing a first cardiac event, and the label indication is written for established disease [1][2].

How semaglutide works

Semaglutide is a GLP-1 receptor agonist with 94% sequence homology to human GLP-1. It binds and activates the GLP-1 receptor, including receptors in brain regions that regulate appetite and calorie intake, and it delays gastric emptying. The label states that the exact mechanism of cardiovascular risk reduction is not established [2].

Safety points from the label

• Heart rate. The label describes a mean rise of 1 to 4 beats per minute, with an increase of 20 beats per minute or more in 26% of semaglutide-treated patients versus 16% of placebo-treated patients, and advises monitoring heart rate at regular intervals [2].
• Gastrointestinal reactions and fluid loss. In pooled weight-management trials, nausea occurred in 44% versus 16% and vomiting in 24% versus 6% [2]. Severe gastrointestinal reactions occurred in 4.1% versus 0.9% [2]. The label warns about acute kidney injury from volume depletion; in Wegovy trials this occurred at 0.4 versus 0.2 cases per 100 patient-years (7 versus 4 adults), more often in people with existing kidney impairment and during dose titration, often after gastrointestinal fluid loss [2].
• Pulmonary aspiration. Reported during general anesthesia or deep sedation; the label instructs patients to tell healthcare providers about planned surgeries or procedures [2].
• Other label warnings include acute pancreatitis, acute gallbladder disease, and the statement that the drug is not recommended in patients with severe gastroparesis [2].
• Boxed warning. Semaglutide caused thyroid C-cell tumors in rodents at clinically relevant exposures; whether it does so in humans is unknown, and it is contraindicated with a personal or family history of medullary thyroid carcinoma or MEN 2 [2].
• Pregnancy. For cardiovascular risk reduction or weight reduction, the label says to discontinue Wegovy when pregnancy is recognized, and at least 2 months before a planned pregnancy because of the long half-life [2].
• Other medicines. Insulin and sulfonylureas raise hypoglycemia risk [2]. Delayed gastric emptying can change absorption of oral drugs; with the semaglutide tablet, levothyroxine exposure rose 33%, while no clinically significant effect was seen on warfarin, metformin, lisinopril, digoxin or rosuvastatin [2].

What happens to weight when treatment stops

In the STEP 1 extension, 327 participants had lost a mean 17.3% of body weight on semaglutide versus 2.0% on placebo by week 68. One year after treatment stopped, they had regained 11.6 and 1.9 percentage points respectively, leaving a net loss of 5.6% versus 0.1%, and cardiometabolic measures reverted toward baseline for most variables [3]. A separate 104-week trial of 304 adults found a mean weight change of -15.2% versus -2.6% while treatment continued [4].

How this compares with earlier semaglutide cardiovascular data

SUSTAIN-6 gave semaglutide 0.5 mg or 1 mg, doses available in Ozempic, to 3,297 adults with type 2 diabetes for 104 weeks and found the same three-part composite in 6.6% versus 8.9% (HR 0.74, 95% CI 0.58 to 0.95) [5]. Ozempic carries its own indication for MACE risk reduction in adults with type 2 diabetes and established cardiovascular disease [6]. The dose, the population and the follow-up differ from SELECT, so the two percentages should not be lined up as if they were a fair comparison.

The practical answer

For an adult with established cardiovascular disease and a BMI of 27 or higher, the Wegovy label supports semaglutide 2.4 mg for reducing the risk of the three-part cardiovascular composite, with an absolute difference of 1.5 percentage points over a mean follow-up of roughly 3.3 years in SELECT [1][2]. The largest component difference was in fatal or non-fatal heart attack (2.8% versus 3.8%, HR 0.72) [2]. The label's warnings cover heart rate, severe gastrointestinal reactions, volume depletion and aspiration during anesthesia [2].