GLP-1 Drugs and Heart Disease: Cardiovascular Trials
GLP-1 Cardiovascular
12% MACE reduction
A 2019 meta-analysis of seven cardiovascular outcome trials found GLP-1 receptor agonists reduced major adverse cardiovascular events by 12% across 56,004 participants.
Kristensen et al., Lancet Diabetes Endocrinol, 2019
Kristensen et al., Lancet Diabetes Endocrinol, 2019
View as imageGLP-1 receptor agonists were built to lower blood sugar. The cardiovascular data that followed was not part of the original plan. Starting with the LEADER trial in 2016, a series of large randomized trials began reporting something the diabetes field did not fully expect: patients on certain GLP-1 drugs had fewer heart attacks, strokes, and cardiovascular deaths.[1] By 2023, the SELECT trial extended that finding to patients with obesity who had no diabetes at all, reducing major cardiovascular events by 20%.[2]
This is the hub for everything RethinkPeptides covers on GLP-1 drugs and cardiovascular disease. Each section below maps to a deeper article on a specific aspect: the SELECT trial's results, blood pressure effects, anti-inflammatory mechanisms, atherosclerosis data, and heart failure outcomes.
Key Takeaways
- The LEADER trial (9,340 patients) found liraglutide reduced the composite of cardiovascular death, heart attack, or stroke by 13% (HR 0.87) over 3.8 years
- SUSTAIN-6 (3,297 patients) showed semaglutide cut MACE by 26% (HR 0.74), driven primarily by a 39% reduction in nonfatal stroke
- The SELECT trial (17,604 patients without diabetes) demonstrated semaglutide 2.4 mg reduced MACE by 20% (HR 0.80, 95% CI 0.72-0.90) in people with obesity and existing cardiovascular disease
- A Kristensen et al. meta-analysis pooling seven CVOTs (56,004 participants) found an overall 12% MACE reduction (HR 0.88, 95% CI 0.82-0.94, p<0.0001) for the GLP-1 class
- SURPASS-CVOT (2025) found tirzepatide was noninferior to dulaglutide for cardiovascular events (HR 0.92), though it did not achieve superiority
- The STEP-HFpEF trials showed semaglutide improved symptoms and reduced body weight in patients with obesity-related heart failure with preserved ejection fraction
The cardiovascular outcome trial era for GLP-1 drugs
The story begins with a regulatory mandate. After rosiglitazone raised concerns about cardiovascular harm from diabetes drugs in 2007, the FDA required all new glucose-lowering therapies to prove cardiovascular safety through dedicated outcome trials. GLP-1 receptor agonist manufacturers had to run these trials. What they found went well beyond safety.
Seven major cardiovascular outcome trials (CVOTs) tested GLP-1 receptor agonists between 2015 and 2019: ELIXA (lixisenatide), LEADER (liraglutide), SUSTAIN-6 (semaglutide), EXSCEL (exenatide), HARMONY Outcomes (albiglutide), REWIND (dulaglutide), and PIONEER 6 (oral semaglutide). Each trial enrolled patients with type 2 diabetes at elevated cardiovascular risk and measured a primary composite of cardiovascular death, nonfatal myocardial infarction, and nonfatal stroke, known as three-point MACE.
The results split into three groups. Liraglutide, semaglutide, dulaglutide, and albiglutide showed statistically significant reductions in MACE.[1][3][4] Exenatide and lixisenatide showed safety (no excess risk) but not significant benefit. Oral semaglutide in PIONEER 6 trended toward benefit but was underpowered for superiority, with only 3,183 patients followed for a median of 1.3 years.
For a detailed analysis of how GLP-1 drugs reduce arterial plaque, see our coverage of GLP-1 agonists and atherosclerosis.
The trials that showed safety but not superiority
Three CVOTs did not reach statistical superiority for MACE reduction, and the reasons matter for interpreting the overall evidence.
ELIXA (lixisenatide, 2015) enrolled 6,068 patients with type 2 diabetes who had experienced an acute coronary syndrome within 180 days. Lixisenatide showed cardiovascular safety (HR 1.02, 95% CI 0.89-1.17) but no benefit. Lixisenatide is a short-acting GLP-1 agonist with a plasma half-life of approximately 3 hours, providing intermittent rather than sustained receptor activation.
EXSCEL (exenatide, 2017) tested once-weekly exenatide in 14,752 patients, the second-largest GLP-1 CVOT. The three-point MACE result was a borderline 9% reduction (HR 0.91, 95% CI 0.83-1.00, p=0.06 for superiority). The result was suggestive but not conclusive. Medication adherence was a potential confounding factor: approximately 43% of patients in the exenatide group discontinued treatment prematurely.
PIONEER 6 (oral semaglutide, 2019) enrolled 3,183 patients followed for only 1.3 years. The three-point MACE hazard ratio was 0.79 (95% CI 0.57-1.11), numerically favoring oral semaglutide but not statistically significant. The trial was designed as a safety trial, not a superiority trial, and was underpowered to detect the modest effect sizes seen in other GLP-1 CVOTs.
The pattern across these three trials is consistent with the hypothesis that sustained GLP-1 receptor activation matters more than peak receptor binding, and that trial design (population size, follow-up duration, adherence) can obscure real effects.
HARMONY Outcomes: albiglutide's short-lived contribution
The HARMONY Outcomes trial deserves separate mention because of its strong result and its unusual aftermath. Published in 2018, it enrolled 9,463 patients with type 2 diabetes and established atherosclerotic cardiovascular disease, testing albiglutide (30-50 mg weekly) against placebo over a median 1.6 years of follow-up.
Three-point MACE was reduced by 22% (HR 0.78, 95% CI 0.68-0.90, p<0.001), one of the largest reductions in any GLP-1 CVOT. The benefit was driven primarily by a 25% reduction in myocardial infarction (HR 0.75, 95% CI 0.61-0.90). Cardiovascular death trended lower but was not statistically significant (HR 0.93, 95% CI 0.73-1.19).
Despite this strong cardiovascular result, albiglutide (marketed as Tanzeum) was withdrawn from the market in 2018 for commercial reasons. Sales had been low due to the drug's injection device and competition from better-tolerated alternatives. The HARMONY data remains scientifically relevant as evidence supporting the cardiovascular benefit of the GLP-1 class as a whole.
GLP-1 cardiovascular trial comparison
| Trial | Drug | N | MACE HR (95% CI) | Follow-up | Population |
|---|---|---|---|---|---|
| ELIXA | Lixisenatide | 6,068 | 1.02 (0.89-1.17) | 2.1 years | T2D + recent ACS |
| LEADER | Liraglutide | 9,340 | 0.87 (0.78-0.97) | 3.8 years | T2D + high CV risk |
| SUSTAIN-6 | Semaglutide | 3,297 | 0.74 (0.58-0.95) | 2.1 years | T2D + high CV risk |
| EXSCEL | Exenatide QW | 14,752 | 0.91 (0.83-1.00) | 3.2 years | T2D (73% CVD) |
| HARMONY | Albiglutide | 9,463 | 0.78 (0.68-0.90) | 1.6 years | T2D + ASCVD |
| REWIND | Dulaglutide | 9,901 | 0.88 (0.79-0.99) | 5.4 years | T2D (31% CVD) |
| PIONEER 6 | Oral semaglutide | 3,183 | 0.79 (0.57-1.11) | 1.3 years | T2D + high CV risk |
| SELECT | Semaglutide 2.4 mg | 17,604 | 0.80 (0.72-0.90) | 3.3 years | Obesity + CVD, no DM |
LEADER: liraglutide sets the benchmark
The LEADER trial, published in 2016, randomized 9,340 patients with type 2 diabetes and high cardiovascular risk to liraglutide 1.8 mg daily or placebo, with both groups receiving standard care.[1] The median follow-up was 3.8 years.
The primary outcome (three-point MACE) occurred in 13.0% of the liraglutide group versus 14.9% in the placebo group (HR 0.87, 95% CI 0.78-0.97, p=0.01 for superiority). Cardiovascular death drove much of the difference: 4.7% with liraglutide versus 6.0% with placebo (HR 0.78, 95% CI 0.66-0.93). All-cause mortality also favored liraglutide (HR 0.85, 95% CI 0.74-0.97).
The population enrolled was high-risk: 81% had established cardiovascular disease, the mean age was 64 years, and median diabetes duration was 12.8 years. The trial was not designed to determine whether benefit extended to lower-risk populations or to people without diabetes.
SUSTAIN-6: semaglutide and stroke reduction
SUSTAIN-6 tested subcutaneous semaglutide (0.5 mg or 1.0 mg weekly) against placebo in 3,297 patients with type 2 diabetes, 83% of whom had established cardiovascular disease, chronic kidney disease, or both.[3] The trial ran for 104 weeks.
Three-point MACE occurred in 6.6% of semaglutide patients versus 8.9% of placebo patients (HR 0.74, 95% CI 0.58-0.95, p=0.02 for superiority). The 26% MACE reduction was the largest seen in any GLP-1 CVOT in diabetes populations. The benefit was driven primarily by nonfatal stroke, which dropped 39% (HR 0.61, 95% CI 0.38-0.99). Nonfatal myocardial infarction showed a non-significant 26% reduction.
A finding that raised questions: retinopathy complications were more common with semaglutide (3.0% vs 1.8%). Later analyses attributed this to the rapid HbA1c reduction rather than a direct drug effect, a pattern seen with intensive glucose lowering in other contexts.
REWIND: expanding the evidence to lower-risk patients
The REWIND trial was distinct from its predecessors. It enrolled 9,901 patients with type 2 diabetes, but only 31% had established cardiovascular disease at baseline.[4] This made REWIND more of a primary prevention trial than the earlier CVOTs, which focused on patients who already had heart disease.
Dulaglutide 1.5 mg weekly reduced MACE by 12% (HR 0.88, 95% CI 0.79-0.99, p=0.026) over a median follow-up of 5.4 years, the longest of any GLP-1 CVOT. The benefit was consistent whether or not patients had prior cardiovascular events, raising the question of whether GLP-1 drugs might protect against a first heart attack or stroke, not just a second one.
The extended follow-up also provided longer-term safety data, with no new safety signals emerging over 5+ years of dulaglutide exposure.
The SELECT trial: cardiovascular protection without diabetes
The SELECT trial changed the conversation entirely.[2] Published in the New England Journal of Medicine in 2023, it tested semaglutide 2.4 mg weekly against placebo in 17,604 patients aged 45 or older who had a BMI of 27 or higher and established cardiovascular disease but no diabetes.
MACE occurred in 6.5% of semaglutide patients versus 8.0% of placebo patients (HR 0.80, 95% CI 0.72-0.90, p<0.001). This was a 20% reduction in cardiovascular death, nonfatal heart attack, or nonfatal stroke in a population without diabetes. A subsequent analysis by Scirica et al. found that semaglutide also reduced all-cause mortality by 19% (HR 0.81, 95% CI 0.71-0.93).[5]
A prespecified analysis by Deanfield et al. examined patients with baseline heart failure (4,286 of the 17,604 enrolled) and found even larger effects: MACE was reduced by 28% (HR 0.72, 95% CI 0.60-0.87).[6] The composite heart failure endpoint also improved (HR 0.79, 95% CI 0.64-0.98).
A further prespecified analysis by Lingvay et al. found that the cardiovascular benefit was consistent across baseline HbA1c levels, meaning the protection was not explained by glucose lowering.[7] For a complete breakdown of the SELECT trial's design and results, see The SELECT Trial: How Semaglutide Reduced Heart Attacks and Strokes.
SURPASS-CVOT: tirzepatide enters the picture
Tirzepatide is a dual GIP/GLP-1 receptor agonist, structurally distinct from pure GLP-1 drugs. The SURPASS-CVOT trial, published in the New England Journal of Medicine in 2025, tested tirzepatide (up to 15 mg weekly) against dulaglutide 1.5 mg in patients with type 2 diabetes and atherosclerotic cardiovascular disease.[8]
The primary endpoint (three-point MACE) occurred in 12.2% of tirzepatide patients versus 13.1% of dulaglutide patients (HR 0.92, 95.3% CI 0.83-1.01), meeting the threshold for noninferiority (p=0.003) but not for superiority (p=0.09). An expanded four-point MACE that included coronary revascularization favored tirzepatide (HR 0.88, 95% CI 0.88-0.96).
The trial used an active comparator (dulaglutide) rather than placebo, which is an important distinction. Since dulaglutide itself reduces MACE by 12% versus placebo (REWIND), tirzepatide's noninferiority to an active drug means it provides cardiovascular protection. But whether it provides more protection than a pure GLP-1 drug remains unresolved. A 2026 narrative review by Abdul-Hafez et al. examines the mechanistic case for tirzepatide's cardiovascular profile, including its effects on lipids, blood pressure, and endothelial biology.[9]
Heart failure: the STEP-HFpEF program
Heart failure with preserved ejection fraction (HFpEF) is one of the largest unmet needs in cardiology. Patients with obesity are disproportionately affected, and until recently, no therapies targeted the obesity-HFpEF phenotype directly.
The STEP-HFpEF trial, led by Kosiborod et al. and published in 2023, randomized 529 patients with HFpEF and a BMI of 30 or higher to semaglutide 2.4 mg weekly or placebo.[10] At 52 weeks, semaglutide produced clinically meaningful improvements: Kansas City Cardiomyopathy Questionnaire score improved by 7.8 points more than placebo, and 6-minute walk distance increased by 20.3 meters more. Body weight fell by 13.3% with semaglutide versus 1.4% with placebo.
A pooled analysis of STEP-HFpEF and STEP-HFpEF DM (which added patients with type 2 diabetes) by Butler et al. confirmed that semaglutide improved symptoms and exercise function across both populations, with consistent effects across a range of subgroups.[11] A 2024 analysis by Verma et al. found that semaglutide's HFpEF benefits were present regardless of baseline atrial fibrillation status, with greater symptom improvement in patients with AF (KCCQ-CSS +11.5 vs +4.3 points; P interaction=0.001).[12]
For more on dual-agonist heart failure data, see Tirzepatide SUMMIT: Heart Failure Results in Obese Patients.
The meta-analysis view: class effect or drug-specific?
Kristensen et al. published the definitive GLP-1 CVOT meta-analysis in Lancet Diabetes & Endocrinology in 2019, pooling data from all seven completed trials (56,004 participants).[13]
The overall MACE reduction was 12% (HR 0.88, 95% CI 0.82-0.94, p<0.0001). Breaking down the individual components: cardiovascular death was reduced by 12% (HR 0.88, 95% CI 0.81-0.96), nonfatal stroke by 16% (HR 0.84, 95% CI 0.76-0.93), and nonfatal MI was numerically lower but not statistically significant (HR 0.91, 95% CI 0.80-1.03). All-cause mortality decreased by 12% (HR 0.88, 95% CI 0.83-0.95). Hospital admission for heart failure decreased by 9% (HR 0.91, 95% CI 0.83-0.99).
A key finding: the benefit appeared to be driven primarily by drugs with longer half-lives (liraglutide, semaglutide, dulaglutide, albiglutide) rather than shorter-acting agents (lixisenatide, exenatide). This has led to debate about whether cardiovascular protection is a property of sustained GLP-1 receptor activation, not just any GLP-1 receptor binding.
A 2025 meta-analysis by Badve et al. updated the evidence with newer data and found that GLP-1 receptor agonists also reduced composite kidney outcomes, extending the benefit beyond the cardiovascular system.[14]
How GLP-1 drugs may protect the heart
The cardiovascular benefit of GLP-1 drugs does not appear to be explained by glucose lowering alone. Several lines of evidence point to direct vascular and cardiac effects.
Anti-inflammatory pathways. GLP-1 receptor agonists reduce circulating levels of C-reactive protein, interleukin-6, and tumor necrosis factor-alpha. They also shift macrophage polarization in arterial plaques from pro-inflammatory M1 toward anti-inflammatory M2 phenotypes, which may stabilize vulnerable plaques and reduce rupture risk. Our detailed coverage of this topic is at How GLP-1 Drugs Reduce Cardiovascular Inflammation.
Atherosclerosis and endothelial function. Preclinical studies show that GLP-1 receptor agonists reduce endothelial dysfunction, inhibit vascular smooth muscle cell proliferation, and decrease oxidative stress in arterial walls. They limit monocyte adhesion and macrophage recruitment into the endothelium, which are early steps in plaque formation. The timeline of event curve separation in the CVOTs (12-18 months) is consistent with anti-atherosclerotic mechanisms rather than acute cardioprotection. See GLP-1 Agonists and Atherosclerosis: Slowing Artery Disease for the preclinical and imaging evidence.
Blood pressure reduction. GLP-1 drugs modestly lower systolic blood pressure by 2-5 mmHg through natriuresis (increased sodium excretion) and vascular relaxation. While this effect alone would not explain the MACE reductions, it contributes to cumulative risk reduction. More on this at Do GLP-1 Agonists Lower Blood Pressure? The Evidence.
Weight-independent effects. An analysis by Coleman et al. (2025) of post hoc data from the EXSCEL trial found that conventional risk factor changes (weight, blood pressure, lipids) accounted for only a portion of the cardiovascular benefit, suggesting direct vascular or cardiac mechanisms at work.[15] That said, the weight loss itself carries risks in some populations, particularly sarcopenia in older adults on GLP-1 therapy. The SELECT trial's Lingvay et al. analysis showed cardiovascular benefit was consistent across all HbA1c levels, further arguing against a glucose-mediated explanation.[7]
Lipid effects. GLP-1 receptor agonists reduce postprandial triglycerides by 12-30% and modestly lower LDL cholesterol. In the SELECT trial, semaglutide reduced triglycerides by approximately 18% and high-sensitivity C-reactive protein by 37% at 104 weeks, changes that track with reduced atherosclerotic risk independent of LDL lowering.
Regulatory milestones and guideline changes
The cardiovascular evidence has reshaped how major medical societies position GLP-1 drugs.
In March 2024, the FDA approved Wegovy (semaglutide 2.4 mg) for cardiovascular risk reduction in adults with established cardiovascular disease and overweight or obesity, based on the SELECT trial. This was the first cardiovascular indication for any GLP-1 receptor agonist in patients without diabetes.
The American College of Cardiology 2025 clinical guidelines now recommend GLP-1 receptor agonists as a first-line treatment option for weight management in patients with obesity to reduce cardiovascular risk. The European Society of Cardiology similarly updated its position to include GLP-1 agonists in the cardiovascular risk management toolkit for patients with type 2 diabetes and established atherosclerotic disease. These guideline changes reflect a shift: GLP-1 drugs are no longer categorized solely as glucose-lowering agents but as cardiovascular therapies in their own right.
What the evidence does not yet show
The cardiovascular data for GLP-1 drugs is strong, but gaps remain.
Primary prevention is still uncertain. Most CVOT participants had established cardiovascular disease. REWIND included patients without prior events and found consistent benefit, but no trial has been powered specifically for a primary prevention endpoint in low-risk populations.
Not all GLP-1 drugs are equal. Exenatide (EXSCEL) and lixisenatide (ELIXA) did not demonstrate significant MACE reduction. Whether this reflects differences in receptor binding kinetics, half-life, or trial design remains debated. Clinicians cannot assume cardiovascular benefit is identical across all GLP-1 receptor agonists.
Long-term effects beyond 5 years are sparse. REWIND had the longest median follow-up at 5.4 years. Whether cardiovascular protection persists, plateaus, or accelerates over decades of use is unknown.
Heart failure outcomes need more data. The STEP-HFpEF trials showed symptom and functional improvements, but they were not powered for hard endpoints like cardiovascular death or heart failure hospitalization. Larger, longer heart failure outcome trials are needed.
Withdrawal effects are poorly characterized. The SELECT trial and CVOTs did not systematically study what happens to cardiovascular risk when patients discontinue therapy. The durability of benefit after stopping treatment is an open question.
The Bottom Line
GLP-1 receptor agonists have demonstrated consistent cardiovascular protection across multiple large randomized trials. The class reduces major adverse cardiovascular events by approximately 12% in meta-analysis, with individual agents showing reductions of 13-26%. The SELECT trial extended this benefit to patients without diabetes, and the STEP-HFpEF program showed symptomatic improvements in obesity-related heart failure. The mechanisms appear to involve anti-inflammatory, anti-atherosclerotic, and hemodynamic effects beyond glucose and weight reduction. Gaps remain around primary prevention, drug-specific differences, long-term durability, and hard heart failure endpoints.