GLP-1, SGLT2, and the heart: what the trials revealed about weight and cardiovascular risk

Cardiology has been surprised by what the GLP-1 and SGLT2 trials revealed.

The GLP-1 receptor agonists weren't designed as cardiac drugs. Semaglutide and liraglutide came out of the diabetes and obesity pipelines. Empagliflozin, dapagliflozin, and the other SGLT2 inhibitors started the same way. None of them set out to be among the most consequential cardiac drug classes of the last decade.

That's what they've turned out to be. The cardiovascular outcome trials, run after these drugs were already approved for other indications, kept showing effect sizes that aren't typical for cardiovascular trials, with significant reductions in cardiovascular mortality, large drops in heart-failure hospitalizations, and kidney protection that hadn't been anticipated at all. Cardiology kept being surprised by each new readout.

The surprise is informative on its own. Drugs that lower weight and glucose can reduce cardiac outcomes this much only if there was a meaningful amount of cardiac disease tied to the weight to begin with. The trials revealed that disease was often there, unrecognized, in patients who'd been losing the weight without anyone connecting the cardiovascular picture.

The trial findings

The SELECT trial, published in 2023, enrolled 17,604 adults with overweight or obesity and prior cardiovascular disease but without diabetes. Semaglutide reduced major adverse cardiovascular events by 20 percent (HR 0.80, 95% CI 0.72 to 0.90) over an average follow-up of about 3.3 years. The benefit came in patients who weren't diabetic, which clarified that this wasn't simply about glucose lowering.

The SGLT2 inhibitor story is similar in shape. EMPA-REG OUTCOME, in 2015, was the first to show a 38 percent reduction in cardiovascular mortality in patients with type 2 diabetes and established cardiovascular disease. The effect was large enough that cardiologists initially questioned the result. Subsequent trials replicated and extended it. DAPA-HF and EMPEROR-Reduced demonstrated benefit in heart failure with reduced ejection fraction, regardless of diabetes status. EMPEROR-Preserved and DELIVER extended the benefit to HFpEF, the first drug class to cleanly do so. DAPA-CKD and EMPA-KIDNEY showed kidney protection independent of diabetes. FLOW, published in 2024, showed similar kidney and cardiovascular benefits for semaglutide in patients with type 2 diabetes and chronic kidney disease.

The cumulative run is striking, particularly because genuinely new cardiac drug classes are rare. Cardiology waited more than two decades between sacubitril/valsartan and the previous generation of heart-failure therapies. SGLT2 inhibitors and GLP-1 receptor agonists, both arriving from outside cardiology, have become arguably the most important cardiac drug classes of the last decade.

Conditions that often go unrecognized

The implications matter for any patient who has been carrying weight, or who is losing it now on a GLP-1. The drugs work in part because they're treating cardiac disease that came with the weight. Some of that disease was being managed; some of it wasn't being recognized at all. Five conditions in particular are frequently missed in patients whose medical attention has been focused on weight.

Heart failure with preserved ejection fraction (HFpEF). Exertional shortness of breath often gets attributed to deconditioning or weight itself. Patients who would meet HFpEF criteria are frequently never sent for an echocardiogram or NT-proBNP measurement. The STEP-HFpEF trial showed semaglutide produced meaningful symptomatic and functional improvement in patients with obesity and HFpEF, with substantial weight loss and significant gains in quality-of-life scores. Many of those patients had HFpEF that hadn't been formally identified before the trial.

Atrial fibrillation. Palpitations get attributed to anxiety, caffeine, or stress. Paroxysmal AF doesn't appear on a routine in-office EKG. The LEGACY study, an observational cohort, showed that sustained weight loss of 10 percent or more reduced AF burden substantially, with six-fold higher arrhythmia-free survival in the largest weight-loss group compared with the lowest. More recently, a 2026 real-world cohort study of obese patients undergoing catheter ablation for AF found GLP-1 receptor agonist therapy associated with an 18 percent lower risk of AF recurrence (HR 0.82, 95% CI 0.76 to 0.88), along with reductions in progression to permanent AF and in cardiovascular hospitalizations.

Elevated apoB and Lp(a). Standard lipid panels report LDL, HDL, and triglycerides. ApoB, the more direct measure of atherogenic particles, often isn't ordered. Lp(a) almost never is. The 2026 ACC/AHA dyslipidemia recommendations moved both into the baseline. We covered the implications in The new cholesterol guidelines: Lp(a), ApoB, and lower thresholds.

Soft (non-calcified) coronary plaque. A coronary calcium score of zero is reassuring but doesn't rule out soft plaque, which is the kind more prone to rupture. CCTA with AI quantification is the test that detects it. The decision framework is in Cleerly, CCTA, and calcium scores: which heart test, when?

Chronic kidney disease with albuminuria. eGFR alone misses early kidney damage. The urine albumin-to-creatinine ratio is the screening test and isn't part of routine bloodwork. CKD with albuminuria independently predicts cardiovascular events. SGLT2 inhibitors and now semaglutide are guideline-supported therapies for it, with outcome evidence from DAPA-CKD, EMPA-KIDNEY, and FLOW.

The work weight loss alone won't finish

Even with a strong response to a GLP-1, several cardiovascular questions don't fully resolve with weight loss.

Lp(a) is genetically determined. Weight loss doesn't change it. If yours is elevated, the management plan is separate. We covered current and emerging options in Lp(a) therapies, now and soon.

LDL cholesterol drops modestly with weight loss, typically around 10 to 15 percent. For patients with high baseline LDL or established atherosclerosis, that drop rarely reaches target on its own. Statins, ezetimibe, bempedoic acid, and PCSK9 inhibitors remain the levers when LDL or apoB needs to go further.

HFpEF-specific therapy. Weight loss improves HFpEF, but it doesn't replace SGLT2 inhibitors and MRAs, both of which now have outcomes data in HFpEF. The right combination is usually weight loss alongside, not instead of, those medications.

AFib rhythm management. Weight loss reduces AFib burden but doesn't eliminate it in patients with established AF. Anticoagulation, rate or rhythm control, and ablation considerations remain separate clinical questions.

Established kidney damage. SGLT2 inhibitors and semaglutide slow CKD progression, but they don't reverse established albuminuria or scarring. The cardiac risk associated with CKD persists and warrants ongoing management.

The cardiologist's role

For a patient losing weight on a GLP-1, or thinking about starting one, the cardiologist's contribution sits in three areas. None of them involves writing the GLP-1 prescription.

Imaging when warranted. A coronary calcium score and, when appropriate, CCTA with AI quantification identify the plaque picture. Echocardiogram plus NT-proBNP screen for HFpEF when symptoms warrant. None of these is appropriate for every patient on a GLP-1. The decision is based on risk profile and history.

Heart failure and metabolic medications. SGLT2 inhibitors are now a class I recommendation in HFpEF and HFrEF. Finerenone has outcomes data in CKD with type 2 diabetes and overlapping heart failure. These are cardiology decisions whether or not the patient is on a GLP-1.

Lipid optimization. Statin titration to apoB and Lp(a) targets, ezetimibe or PCSK9 inhibitor escalation when needed, and the explicit conversation about whether the residual LDL after weight loss is good enough or warrants intensification.

The GLP-1 stays with whoever prescribed it, whether that's primary care, endocrinology, a weight-management program, or another telehealth platform. The cardiologist's value is in the interpretation and the integration. For more on what a visit covers in this context, our focus page on GLP-1 and cardiac risk walks through it.