What is HFpEF and why is it particularly relevant to obesity?

Heart failure with preserved ejection fraction (HFpEF) is a clinical syndrome in which heart failure symptoms occur in the presence of a left ventricular ejection fraction ≥50%, distinguishing it from HFrEF (reduced EF ≤40%) and HFmrEF (mildly reduced, 41–49%). HFpEF accounts for approximately 50% of all heart failure diagnoses in the UK and has a particularly strong association with obesity, metabolic syndrome, hypertension, and T2DM. The obese HFpEF phenotype — sometimes termed HFpEF-Obese — is characterised by a distinct pathophysiology involving epicardial fat inflammation, adverse cardiac remodelling from excess pericardial adipose tissue, and concentric LV hypertrophy driven by metabolic pressure overload.

What did STEP-HFpEF demonstrate?

STEP-HFpEF (semaglutide 2.4 mg in HFpEF with obesity, BMI ≥30, without T2DM) demonstrated a 7.8-point improvement in the KCCQ-CSS (Kansas City Cardiomyopathy Questionnaire Clinical Summary Score) with semaglutide versus 3.3 points with placebo at 52 weeks — a statistically significant and clinically meaningful difference. The 6-minute walk test distance improved by a mean of 20 metres more in the semaglutide arm, and weight was reduced by 13.3% versus 2.6% with placebo.

Is the HFpEF benefit from semaglutide driven entirely by weight loss?

This is the central mechanistic debate in the STEP-HFpEF literature. An exploratory mediation analysis from the trial estimated that approximately 40–50% of the KCCQ-CSS improvement was attributable to weight reduction and 50–60% to other mechanisms — consistent with direct cardiac GLP-1 receptor effects, anti-inflammatory actions, blood pressure reduction, and improvements in diastolic filling independent of weight. This non-weight-mediated residual effect is consistent with GLP-1 receptor expression in cardiomyocytes and GLP-1 agonist effects on cardiac energetics documented in preclinical models.

Did semaglutide reduce NT-proBNP in STEP-HFpEF?

NT-proBNP (N-terminal pro-B-type natriuretic peptide) is the primary biomarker of cardiac wall stress and intracardiac filling pressure. In STEP-HFpEF, semaglutide produced a greater reduction in NT-proBNP than placebo, with the between-group difference reaching statistical significance. NT-proBNP reduction is considered a strong surrogate of reduced LV filling pressure and is associated with improved prognosis in HFpEF populations.

What is the UK regulatory status of semaglutide for HFpEF?

Semaglutide does not currently hold a specific MHRA licence for HFpEF in the UK. The STEP-HFpEF findings have been reviewed by the European Society of Cardiology (ESC) and incorporated into HFpEF management guidance, but a formal indication extension would require regulatory submission. UK cardiologists may consider semaglutide in patients with HFpEF and obesity under the existing MHRA weight management indication (Wegovy), which encompasses weight-related cardiovascular comorbidities.

Heart Failure (HFpEF): Metabolic Peptide Research (UK 2026)

The condition in 60 seconds

Heart failure with preserved ejection fraction (HFpEF) represents approximately half of the estimated 900,000 heart failure cases in England and poses a greater therapeutic challenge than heart failure with reduced ejection fraction (HFrEF). Unlike HFrEF, which has a robust evidence base for neurohormonal blockade with ACE inhibitors, beta-blockers, and mineralocorticoid receptor antagonists, HFpEF was until recently a syndrome with few disease-modifying pharmacological options — the limited exception being SGLT-2 inhibitors (dapagliflozin, empagliflozin) and, increasingly, semaglutide.

HFpEF is defined by exertional dyspnoea and reduced functional capacity in the presence of normal or near-normal left ventricular systolic function (LVEF ≥50%) but abnormal diastolic filling, elevated filling pressures, and cardiac structural changes such as left atrial dilation and concentric LV hypertrophy. It disproportionately affects older, female, and obese patients — a demographic profile that strongly overlaps with the obesity-associated metabolic syndrome and T2DM population where incretin agonist benefits have been most comprehensively characterised.

Why metabolic peptides matter here

The HFpEF-obese phenotype is now recognised as mechanistically distinct from other HFpEF subtypes. Excess pericardial and epicardial adipose tissue exerts compressive, inflammatory, and paracrine effects on the adjacent myocardium — impairing cardiomyocyte relaxation, inducing fibrosis, and reducing the heart's capacity for the preload-dependent increases in stroke volume required during exercise. This adipose-driven cardiac dysfunction is exactly the pathological context where GLP-1 receptor agonism operates at multiple levels simultaneously: reducing total body adiposity, reducing epicardial fat volume specifically (demonstrated in DXA and MRI sub-studies), reducing systemic inflammation, improving blood pressure, and potentially acting via direct cardiomyocyte GLP-1 receptor signalling.

Cardiomyocytes express GLP-1 receptors, and preclinical data suggest GLP-1 receptor activation can improve cardiomyocyte calcium handling, increase glucose utilisation relative to fatty-acid oxidation (improving energetic efficiency under ischaemic conditions), and attenuate myocardial fibrosis signalling. Whether these direct cardiac effects are clinically operative alongside the weight-mediated benefits in HFpEF is the central question in the field — one the STEP-HFpEF programme has partially addressed.

The trial landscape

STEP-HFpEF (semaglutide 2.4 mg, 2023): The primary trial in a two-trial programme. 529 participants with LVEF ≥45%, HFpEF symptoms (KCCQ-CSS ≤80), BMI ≥30 kg/m², and without T2DM were randomised to semaglutide 2.4 mg weekly or placebo for 52 weeks. Co-primary endpoints were change in KCCQ-CSS (patient-reported symptoms and functional status) and change in body weight. Secondary endpoints included 6-minute walk test distance, C-reactive protein (CRP), NT-proBNP, and a hierarchical clinical composite.

STEP-HFpEF DM (semaglutide 2.4 mg, 2024): A parallel trial with identical design enrolling 616 participants with HFpEF, BMI ≥30, and T2DM — testing whether the findings from STEP-HFpEF generalised to the diabetic HFpEF population. Co-primary endpoints were identical. Results confirmed the KCCQ-CSS improvement and weight reduction with semaglutide in the T2DM-HFpEF population, with effect magnitudes broadly similar to the non-diabetic trial.

SELECT (semaglutide, 2023): The cardiovascular outcomes trial enrolled 17,604 overweight or obese adults with established CVD without diabetes. Heart failure hospitalisation was a pre-specified component of the expanded secondary cardiovascular composite. Semaglutide reduced the composite including heart failure hospitalisation or cardiovascular death by 18%, with heart failure hospitalisation individually showing directional benefit. SELECT provides the broader cardiovascular outcome context for the STEP-HFpEF findings.

SUMMIT (tirzepatide in HFpEF, 2024): A parallel programme for tirzepatide, designed following the STEP-HFpEF blueprint. SUMMIT enrolled participants with HFpEF, obesity, and LVEF ≥50%. Results published in late 2024 demonstrated tirzepatide produced clinically meaningful improvements in KCCQ-CSS and 6MWT distance consistent with STEP-HFpEF, extending the evidence base to the dual GIP/GLP-1 class.

Pivotal findings

STEP-HFpEF KCCQ-CSS: +7.8-point improvement with semaglutide versus +3.3 points with placebo at 52 weeks (difference: +4.5 points, 95% CI 2.5–6.5, p < 0.001) — exceeding the 5-point minimum clinically important difference threshold in the active arm.
STEP-HFpEF body weight: −13.3% with semaglutide versus −2.6% with placebo — confirming the trial achieved pharmacologically meaningful weight reduction as the metabolic backbone of the trial design.
6-minute walk test: +20 metres additional distance with semaglutide versus placebo (95% CI 8–32 m) — a functional exercise capacity gain consistent with clinical improvement in heart failure symptoms.
NT-proBNP: Semaglutide produced a greater reduction in NT-proBNP than placebo (ratio of geometric means 0.86 with semaglutide vs 0.95 with placebo, treatment ratio 0.90, 95% CI 0.84–0.97) — biomarker evidence of reduced LV filling pressure.
STEP-HFpEF DM (diabetic cohort): KCCQ-CSS improved by +7.3 points with semaglutide versus +3.4 points with placebo — essentially replicating the non-diabetic cohort finding and confirming class effect across the full obesity-HFpEF spectrum.

UK clinical and research positioning

The European Society of Cardiology (ESC) 2023 Heart Failure guidelines supplement acknowledged the STEP-HFpEF findings, and the ESC 2024 focused update on obesity-related HFpEF incorporated GLP-1 receptor agonists as a class IIb recommendation for symptom improvement and weight reduction in obese HFpEF patients without T2DM. In the UK, the NICE chronic heart failure guidelines (NG196) are scheduled for review in 2025–2026, and cardiologists anticipate GLP-1 agonist inclusion in the HFpEF pharmacological pathway given the strength of STEP-HFpEF.

The MHRA's existing Wegovy weight management licence encompasses obesity with weight-related cardiovascular comorbidities — a category under which HFpEF may qualify, providing a legal prescribing basis for UK cardiologists managing obese HFpEF patients even ahead of a specific HFpEF indication extension. UK heart failure specialist nurses and community HF services have begun incorporating discussions of metabolic weight management into their patient pathways, recognising the overlap with the pharmacological evidence base.

Methodological caveats

STEP-HFpEF used KCCQ-CSS as a patient-reported outcome co-primary endpoint, which is susceptible to unblinding bias in a weight-loss trial where substantial visible changes in body composition may alter patient self-perception. The trial excluded patients with recent hospitalisation for acute heart failure, limiting applicability to the most severe HFpEF phenotypes. The 52-week duration is insufficient to determine whether the KCCQ improvement translates to reduced hospitalisation or mortality, which are the outcomes NHS commissioners typically prioritise for investment decisions. Long-term HFpEF morbidity and mortality outcome trials (analogous to the DAPA-HF and EMPEROR-Preserved trials for SGLT-2 inhibitors) have not yet been completed for the GLP-1 class.

Frequently asked questions

What is HFpEF and why is it particularly relevant to obesity?: Heart failure with preserved ejection fraction (HFpEF) is a clinical syndrome in which heart failure symptoms occur in the presence of a left ventricular ejection fraction ≥50%, distinguishing it from HFrEF (reduced EF ≤40%) and HFmrEF (mildly reduced, 41–49%). HFpEF accounts for approximately 50% of all heart failure diagnoses in the UK and has a particularly strong association with obesity, metabolic syndrome, hypertension, and T2DM. The obese HFpEF phenotype — sometimes termed HFpEF-Obese — is characterised by a distinct pathophysiology involving epicardial fat inflammation, adverse cardiac remodelling from excess pericardial adipose tissue, and concentric LV hypertrophy driven by metabolic pressure overload.
What did STEP-HFpEF demonstrate?: STEP-HFpEF (semaglutide 2.4 mg in HFpEF with obesity, BMI ≥30, without T2DM) demonstrated a 7.8-point improvement in the KCCQ-CSS (Kansas City Cardiomyopathy Questionnaire Clinical Summary Score) with semaglutide versus 3.3 points with placebo at 52 weeks — a statistically significant and clinically meaningful difference. The 6-minute walk test distance improved by a mean of 20 metres more in the semaglutide arm, and weight was reduced by 13.3% versus 2.6% with placebo.
Is the HFpEF benefit from semaglutide driven entirely by weight loss?: This is the central mechanistic debate in the STEP-HFpEF literature. An exploratory mediation analysis from the trial estimated that approximately 40–50% of the KCCQ-CSS improvement was attributable to weight reduction and 50–60% to other mechanisms — consistent with direct cardiac GLP-1 receptor effects, anti-inflammatory actions, blood pressure reduction, and improvements in diastolic filling independent of weight. This non-weight-mediated residual effect is consistent with GLP-1 receptor expression in cardiomyocytes and GLP-1 agonist effects on cardiac energetics documented in preclinical models.
Did semaglutide reduce NT-proBNP in STEP-HFpEF?: NT-proBNP (N-terminal pro-B-type natriuretic peptide) is the primary biomarker of cardiac wall stress and intracardiac filling pressure. In STEP-HFpEF, semaglutide produced a greater reduction in NT-proBNP than placebo, with the between-group difference reaching statistical significance. NT-proBNP reduction is considered a strong surrogate of reduced LV filling pressure and is associated with improved prognosis in HFpEF populations.
What is the UK regulatory status of semaglutide for HFpEF?: Semaglutide does not currently hold a specific MHRA licence for HFpEF in the UK. The STEP-HFpEF findings have been reviewed by the European Society of Cardiology (ESC) and incorporated into HFpEF management guidance, but a formal indication extension would require regulatory submission. UK cardiologists may consider semaglutide in patients with HFpEF and obesity under the existing MHRA weight management indication (Wegovy), which encompasses weight-related cardiovascular comorbidities.

Related peptide profiles: Semaglutide · Tirzepatide. Brand references: Wegovy · Ozempic. Compare: Semaglutide vs Tirzepatide. Also see: Obesity research evidence.