GLP-1 and HFrEF Heart Failure: The Evidence (2026)

If you have heart failure and you take — or are considering — a GLP-1 drug like Ozempic, Wegovy, Mounjaro or Zepbound, the single most important thing to understand is that “heart failure” is not one disease, and the evidence splits sharply by type. In heart failure with preserved ejection fraction (HFpEF) — the kind tightly linked to obesity — randomized trials of semaglutide (STEP-HFpEF) and tirzepatide (SUMMIT) showed clear benefit. But in heart failure with reduced ejection fraction (HFrEF) — a weak, enlarged pumping chamber — the older randomized trials of liraglutide (FIGHT and LIVE) found no benefit, a faster heart rate, and signals of possible harm (Margulies 2016 ^[1]; Jorsal 2017 ^[2]). That is why specialists are positive about GLP-1s in obesity-related HFpEF but cautious in HFrEF. This article walks through both sides of that divide so you can have an informed conversation with your cardiologist. For the encouraging HFpEF side, see our GLP-1 and HFpEF patient guide and the STEP-HFpEF and SUMMIT deep-dive.

The honest summary

• HFpEF and HFrEF are different diseases. HFpEF (preserved EF, often ≥50%) is a stiff heart that fills poorly and is strongly tied to obesity. HFrEF (reduced EF, typically ≤40%) is a weakened heart that pumps poorly. The GLP-1 evidence points in opposite directions for the two.
• In HFpEF the evidence is positive. Semaglutide (STEP-HFpEF, NEJM 2023) and tirzepatide (SUMMIT, NEJM 2025) both improved symptoms and exercise capacity in obesity-related HFpEF, and SUMMIT reduced cardiovascular death or worsening heart failure (Kosiborod 2023^[3]; Packer 2025^[4]).
• In HFrEF the randomized evidence is not positive. The FIGHT trial of liraglutide in advanced HFrEF found no improvement in its primary endpoint and numerically more deaths and heart-failure hospitalizations in the liraglutide group (Margulies 2016^[1]).
• A faster heart rate is the recurring safety signal. GLP-1 drugs raise resting heart rate by a few beats per minute. In a weakened HFrEF heart that is a real concern, and FIGHT/LIVE both documented it (Margulies 2016^[1]; Jorsal 2017^[2]).
• The LIVE trial saw more serious cardiac events. In stable chronic heart failure (mostly reduced-EF), liraglutide did not improve heart function and was linked to more serious cardiac adverse events, including arrhythmias (Jorsal 2017^[2]).
• Bottom line: type matters. A GLP-1 may be reasonable for obesity, diabetes, or HFpEF — but in HFrEF the decision is individualized and cautious, and should be made with a cardiologist. Do not start or stop on your own.

First, the two kinds of heart failure

Doctors split heart failure by ejection fraction (EF) — the percentage of blood the left ventricle squeezes out with each beat. A normal EF is roughly 50–70%. Heart failure with reduced ejection fraction (HFrEF) means the main pumping chamber is weak and dilated, with an EF usually at or below 40%; it is the “classic” systolic heart failure treated with a well-established drug regimen (beta-blockers, ACE inhibitors/ARBs/ARNI, mineralocorticoid antagonists, and SGLT2 inhibitors). Heart failure with preserved ejection fraction (HFpEF) means the heart squeezes normally (EF ≥50%) but is stiff and fills poorly; it is far more closely tied to obesity, and until recently had few proven drug therapies.

That distinction is the whole story here. The reason GLP-1 drugs look good in HFpEF is partly mechanical: a large share of HFpEF is driven by obesity and the inflammation, fluid overload, and exercise limitation that come with it, so a drug that produces major weight loss can directly relieve the disease. HFrEF is a different problem — a damaged, failing pump — and weight loss alone is not the lever, while the heart-rate and metabolic effects of GLP-1s could in theory be unhelpful. Keeping these two diseases separate in your mind is the key to reading any “GLP-1 and heart failure” headline correctly.

The encouraging side: GLP-1s in HFpEF

In obesity-related HFpEF, the randomized evidence is genuinely good. The STEP-HFpEF trial randomized people with obesity-related HFpEF to weekly semaglutide 2.4 mg or placebo and found significantly larger improvements in heart-failure symptoms and physical limitations (the Kansas City Cardiomyopathy Questionnaire score) and in 6-minute walk distance, along with weight loss and lower inflammation (Kosiborod 2023^[3]). A companion trial in people who also had type 2 diabetes (STEP-HFpEF DM) and a pooled analysis of both trials confirmed the symptom and functional benefits (Butler 2024^[5]).

The SUMMIT trial took it a step further with tirzepatide in obesity-related HFpEF. Beyond improving symptoms and exercise tolerance, SUMMIT reduced a composite of cardiovascular death or worsening heart failure compared with placebo (Packer 2025^[4]). Secondary analyses showed tirzepatide reduced markers of congestion and circulatory overload, and a cardiac-MRI substudy found reductions in left-ventricular mass and the fat around the heart (Zile 2025^[6]; Borlaug 2025^[7]). The broader cardiovascular picture is reassuring too: in people with obesity but without diabetes, semaglutide cut major cardiovascular events in the large SELECT trial (Lincoff 2023^[8]). All of that is the optimistic context — and it is mostly about HFpEF, not HFrEF.

The cautious side: what the HFrEF trials actually found

The reason cardiologists are careful with GLP-1s in HFrEF is not a hunch — it comes from two randomized trials of liraglutide done years before the obesity-drug boom. The most important is the FIGHT trial (Functional Impact of GLP-1 for Heart Failure Treatment), published in JAMA in 2016. FIGHT randomized 300 patients with advanced heart failure and a reduced ejection fraction — many recently hospitalized — to liraglutide or placebo. The result was clearly negative: liraglutide did not improve the primary clinical-stability endpoint (a global rank score combining death, rehospitalization, and a biomarker of heart strain), and the numbers trended the wrong way, with more deaths and more heart-failure hospitalizations in the liraglutide group (Margulies 2016^[1]).

Follow-up analyses of FIGHT sharpened the concern. Liraglutide produced the expected modest weight loss but that did not translate into clinical benefit in this population (Sharma 2018^[9]), and a renal analysis found no protective effect on kidney function in these advanced-HFrEF patients (Redouane 2020^[10]). The takeaway from FIGHT is consistent: in a sick, reduced-EF population, a GLP-1 drug delivered metabolic effects without the cardiac payoff — and possibly some harm.

The second trial, LIVE, published in the European Journal of Heart Failure in 2017, studied liraglutide in stable chronic heart failure (predominantly reduced EF, with and without diabetes). Its mechanistic goal was to see whether liraglutide improved left-ventricular function; it did not. More notably for safety, LIVE reported more serious cardiac adverse events in the liraglutide group, including arrhythmic events such as atrial fibrillation/flutter and ventricular events (Jorsal 2017^[2]). A LIVE imaging substudy likewise found no improvement in myocardial blood flow or glucose uptake (Nielsen 2019^[11]). Two randomized trials, two reduced-EF populations, the same disappointing-to-worrying conclusion.

Important caveats before you over-read the HFrEF trials

• They used liraglutide, not the newer drugs. FIGHT and LIVE tested liraglutide — an older, less potent daily GLP-1. There is no comparable randomized HFrEF trial of semaglutide or of tirzepatide (a dual GLP-1/GIP drug). The HFrEF caution is extrapolated from liraglutide, not proven for the newer agents.
• FIGHT enrolled a very sick population. These were advanced-HFrEF patients, many recently hospitalized. A high-risk group makes harm easier to detect but also harder to generalize to a stable outpatient with mild reduced-EF heart failure.
• The signals were not all formally “significant.” FIGHT's excess deaths and hospitalizations were numerical trends in a 300-patient trial, not a definitive proof of harm. The honest reading is “no benefit, with worrying signals,” not “GLP-1s kill HFrEF patients.”
• SGLT2 inhibitors are the diabetes drug with proven HFrEF benefit. If the goal is a glucose-lowering drug that also helps a reduced-EF heart, SGLT2 inhibitors — not GLP-1s — are the class with strong randomized evidence in HFrEF. That matters when weighing options in someone with both diabetes and HFrEF.
• Obesity and diabetes still matter. Many HFrEF patients also have obesity or diabetes, where GLP-1s have real value. The question is rarely “never” — it is whether the metabolic upside outweighs the cardiac caution for you, decided with a cardiologist.

What this means if you have HFrEF and want a GLP-1

• Know your ejection fraction. Ask your doctor whether your heart failure is reduced-EF (HFrEF) or preserved-EF (HFpEF). The entire risk–benefit conversation hinges on that one number, and patients often do not know which type they have.
• Loop in your cardiologist, not just the prescriber. A telehealth weight-loss prescription should not be the only voice in a HFrEF decision. The cardiologist managing your heart-failure medications needs to weigh in.
• Make sure guideline-directed HFrEF therapy comes first. Beta-blockers, ACE inhibitors/ARBs/ARNI, mineralocorticoid antagonists, and SGLT2 inhibitors are the proven life-saving HFrEF drugs. A GLP-1 is, at most, an add-on for obesity or diabetes — never a substitute.
• Watch heart rate and symptoms if you do start one. Report a rising resting heart rate, palpitations, new shortness of breath, weight gain from fluid, or reduced exercise tolerance. For more on the heart-rate effect, see GLP-1s, heart rate and palpitations.
• Don't stop heart-failure meds to make room. Whatever you and your team decide about a GLP-1, it should not come at the cost of reducing the medications that are actually keeping a reduced-EF heart stable.

Bottom line

The phrase “GLP-1 drugs and heart failure” hides a split verdict. For obesity-related heart failure with preserved ejection fraction, the randomized evidence is positive — semaglutide and tirzepatide improved symptoms and function, and tirzepatide reduced cardiovascular death or worsening heart failure (Kosiborod 2023^[3]; Packer 2025^[4]). For heart failure with reduced ejection fraction, the only randomized trials — both using liraglutide — found no benefit, a faster heart rate, and signals of possible harm (Margulies 2016^[1]; Jorsal 2017^[2]). The newer drugs have not been tested head-on in HFrEF, so caution is extrapolated, not proven, but it is the prudent default. If you have HFrEF, the right move is not a self-started prescription — it is a conversation with your cardiologist about your specific ejection fraction, your other heart-failure medications, and whether the metabolic benefits are worth the cardiac caution in your case.

This article is educational and is not medical advice. Every claim above is sourced to a peer-reviewed randomized trial, trial substudy, or pooled analysis indexed in PubMed and verified against the live PubMed database before publication. Decisions about GLP-1 drugs in heart failure — especially reduced-ejection-fraction heart failure — should be made with the cardiologist managing your care.