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Abstract Background Heart failure with preserved ejection fraction (HFpEF) is a heterogeneous syndrome comprising multiple pathophysiological phenotypes. HFpEF trials have largely enrolled diverse populations and reported average treatment effects, consistently yielding neutral results that may obscure drug-specific benefits within distinct subgroups. To address this issue, we employ an interaction-based that incorporates treatment-by-variable interactions to uncover drug-specific responses. Methods We leveraged four HFpEF clinical trials (TOPCAT, RELAX, NEAT-HFpEF, INDIE-HFpEF) and developed a framework comprising two complementary approaches. The first employed a prognostic responder model to evaluate whether conventional responder definitions reflect treatment-specific benefit or instead capture favorable clinical trajectories common to both treatment and placebo groups. The second used an interaction-based individual treatment effect (ITE) modeling to identify baseline variables that modify therapy effect, distinguishing drug-specific response from prognostic phenotypes. Results Although the prognostic responder model demonstrated good discrimination, further analisys suggested it primarily captured a prognostic signal associated with favorable clinical trajectories common to both treatment and placebo arms. In contrast, the ITE model identified distinct, drug-specific effect modifiers across trials (cardiorenal-inflammatory for spironolactone (TOPCAT), NO-mediated anti-inflammatory for isosorbide mononitrate (NEAT-HFpEF), afterload-reducing for inorganic nitrite (INDIE-HFpEF), and anti–volume-overload for sildenafil (RELAX). Each ITE model demonstrated significance only within its own trial suggesting drug-specific signal. Conclusions The proposed method identifies mechanism-specific effect modifiers, and uncovers clinically meaningful heterogeneity in treatment response, which is not captured by conventional MCID-based approaches. Although exploratory, these findings support phenotype-guided therapy in HFpEF and argue for phenotype-informed trial design to enhance treatment-effect detection and therapy targeting. Graphical Abstract

Importance Excess body fat plays a pivotal role in the pathogenesis of heart failure with preserved ejection fraction (HFpEF). HU6 is a novel, controlled metabolic accelerator that enhances mitochondrial uncoupling resulting in increased metabolism and fat-specific weight loss. Objective To assess efficacy and safety of HU6 in reducing body weight, improving peak volume of oxygen consumption (VO 2 ) and body composition among patients with obesity-related HFpEF. Design, Setting, and Participants The Exploratory Phase 2A, Double-Blind, Placebo-Controlled Dose Escalation Study of Safety, Tolerability, Pharmacodynamics, and Pharmacokinetics of HU6 for Subjects With Obese HFpEF (HuMAIN-HFpEF) trial was a multicenter, dose-escalation randomized clinical trial among patients with chronic stable HFpEF and obesity. Data were analyzed from July to October 2024. Intervention HU6 treatment for 19 weeks, starting at 150 mg per day and potentially up titrated to 450 mg per day based on safety and tolerability vs placebo. Main Outcomes and Measures The primary end point was change in body weight. Results Of 66 participants randomized (mean [SD] age, 64.5 [12] years; 38 female [58%]; mean [SD] weight, 110.9 [22.4] kg), 56 completed the trial. HU6 (vs placebo) significantly decreased weight (between-group difference, −2.86 kg; 95% CI, −4.68 to −1.04 kg; P = .003), total fat mass (between-group difference, −2.96 kg; 95% CI, −4.50 to −1.42 kg; P < .001), and percentage visceral fat (between-group difference,−1.3%; 95% CI, −2.1 to −0.5%; P = .003), with no significant loss of muscle mass. There were no statistically significant changes in peak VO 2 , 6-minute walk distance, Kansas City Cardiomyopathy Questionnaire score, high-sensitivity C-reactive protein level, N-terminal pro–brain natriuretic peptide level, or diastolic function. Serious adverse events were noted in 5 participants (4 in the HU6 group; 1 in the placebo group), including 1 death, all judged unrelated to treatment. Conclusions and Relevance Among patients with obesity-related HFpEF, treatment with HU6 for 19 weeks led to modest but statistically significant weight loss without significant changes in peak VO 2 . Larger trials of longer duration are warranted to determine whether longer-term administration of HU6 can improve exercise function, quality of life, and cardiovascular outcomes in this increasingly common disorder. Trial Registration ClinicalTrials.gov Identifier: NCT05284617

BACKGROUND: Plasma NT-proBNP (N-terminal pro-B-type natriuretic peptide) is commonly used to diagnose heart failure with preserved ejection fraction (HFpEF), but its diagnostic performance in the ambulatory/outpatient setting is unknown because previous studies lacked objective reference standards. METHODS: Among patients with chronic dyspnea, diagnosis of HFpEF or noncardiac dyspnea was determined conclusively by exercise catheterization in a derivation cohort (n=414), multicenter validation cohort 1 (n=560), validation cohort 2 (n=207), and a nonobese Japanese validation cohort 3 (n=77). Optimal NT-proBNP cut points for HFpEF rule out (optimizing sensitivity) and rule in (optimizing specificity) were derived and tested, stratified by obesity and atrial fibrillation. Derived cut points were tested in 3 additional validation cohorts (cohorts 4–6) in whom HFpEF was diagnosed by resting catheterization only (n=260), previous hospitalization for heart failure (n=447), or exercise echocardiography (n=517), respectively. RESULTS: Current recommended rule-out NT-proBNP threshold <125 pg/mL had 82% sensitivity (95% CI, 77%–88%) with a body mass index (BMI) <35 kg/m 2 , decreasing to 67% (95% CI, 58%–77%) with a BMI ≥35 kg/m 2 . A lower rule-out NT-proBNP threshold <50 pg/mL displayed good sensitivity with a BMI <35 kg/m 2 (97% [95% CI, 95%–99%]), with a modest decline in sensitivity with a BMI ≥35 kg/m 2 (86% [95% CI, 79%–93%]); diagnostic thresholds were confirmed in validation cohorts 1 and 2 (91% [95% CI, 88%–95%] and 86% [95% CI, 80%–93%] with a BMI <35 kg/m 2 ; 80% [95% CI, 74%–87%] and 84% [95% CI, 74%–93%] with a BMI ≥35 kg/m 2 ). Current consensus age- and BMI-stratified rule-in thresholds demonstrated only 65% specificity (95% CI, 57%–72%). Rule-in NT-proBNP threshold ≥500 pg/mL had 85% specificity (95% CI, 78%–91%) with a BMI <35 kg/m 2 (87% [95% CI, 80%–94%] and 90% [95% CI, 81%–99%] in validation cohorts), with 100% specificity at a BMI ≥35 kg/m 2 (93% [95% CI, 81%–100%] and 100% in validation cohorts). With a BMI ≥35 kg/m 2 , lower rule-in thresholds (≥220 pg/mL) provided good specificity (88% [95% CI, 73%–100%]; 93% [95% CI, 81%–100%] and 100% in validation cohorts). Findings were consistent in validation cohorts 3 through 6 (sensitivity of <50 pg/mL, 93%–98%; specificity of ≥500 pg/mL, 82%–89%). NT-proBNP provided no incremental discrimination among patients with history of AF; ≥98% of patients with AF and dyspnea were found to have HFpEF in our cohorts. CONCLUSIONS: In patients with chronic unexplained dyspnea, current rule-in and rule-out NT-proBNP diagnostic thresholds lead to unacceptably high error rates, with important interactions by obesity and AF status. In our study, NT-proBNP provided little value in those with AF and dyspnea because the presence of AF is by itself a robust biomarker of HFpEF. Use of separate rule-in and rule-out diagnostic thresholds stratified by BMI reduces miscategorization and can guide more appropriate use of exercise testing for possible HFpEF.

Abstract Aims Sodium–glucose co-transporter-2 (SGLT2) inhibitors improve health status and outcomes in the setting of heart failure (HF) across the range of ejection fraction (EF). Baseline kidney disease is common in HF, complicates HF management and is strongly linked to worse health status. This study aimed to assess whether the treatment effects of dapagliflozin on health status vary based on estimated glomerular filtration rate (eGFR). Methods and Results We conducted a pooled participant-level analysis of two double-blind, randomized trials, DEFINE-HF (n = 236) and PRESERVED-HF (n = 324), which evaluated dapagliflozin versus placebo. Both multicentre studies enrolled adults with HF, New York Heart Association Class II or higher, elevated natriuretic peptides, and an EF &lt; 40% in DEFINE-HF or &gt;45% in PRESERVED-HF. The primary exposure was eGFR. The main outcome was the Kansas City Cardiomyopathy Questionnaire Clinical Summary Score (KCCQ-CSS) at 12 weeks. Across both trials, there were 583 (99.3%) participants with a baseline eGFR. The median (25th, 75th) eGFR was 59 (46, 77) mL/min/1.73 m2. Dapagliflozin improved KCCQ-CSS at 12 weeks [placebo-adjusted difference, +5.0 points, 95% confidence interval (CI) 2.6–7.5; P &lt; 0.001], and this was consistent in participants with an eGFR ≥ 60 (+6.0 points, 95% CI 2.4–9.7; P = 0.001) and eGFR &lt; 60 (+4.1 points, 95% CI 0.5–7.7; P = 0.025) (P interaction = 0.46). The benefits of dapagliflozin on KCCQ-CSS remained robust across eGFR when modelled as a continuous variable (P interaction = 0.48). Conclusions Dapagliflozin led to early and clinically meaningful improvements in health status in HF patients, regardless of EF or baseline eGFR.

Introduction: Patients with heart failure with preserved ejection fraction (HFpEF) have a high burden of comorbidities. To recognize the complex interplay of obesity, diabetes, and chronic kidney disease (CKD) in patients with cardiovascular disease, the cardiovascular-kidney-metabolic (CKM) syndrome was recently defined, but data on the burden of CKM in HFpEF is limited. Aim: We sought to describe the prevalence of CKM components in HFpEF leveraging data from control participants in clinical trials and NHANES. Methods: We analyzed data presented in publications from four randomized clinical trials that enrolled participants with HFpEF (all of which are available via NHLBI BioLINCC and will be included in the extant HeartShare dataset): TOPCAT, RELAX, NEAT-HFpEF, and INDIE. We abstracted baseline demographic and clinical variables from study publications to define CKM components (e.g., body mass index [BMI], diabetes status, hypertension, CKD status). We compared prevalence of CKM in these trials with a representative sample of US adults with self-reported history of heart failure (HF) from NHANES 2011-2018. Results: We included 1937 patients with HFpEF from four trials with enrollment between 2006-2016 and 715 adults representing 5.6 million adults aged ≥40 years with a self-report of HF between 2011-2018 from NHANES ( Table ). Mean age was similar among enrolled trial participants with HFpEF and those with HF in NHANES (~68-69 years). Mean BMI was in the obesity range and was similar among trial participants with HFpEF and HF in NHANES (31-35 kg/m 2 ). A significant proportion of individuals had hypertension in HFpEF trials (>80%) and in the NHANES sample with HF (89%). The proportion of stage ≥ 3 CKD in HFpEF trials (≥ 37%) was similar to the NHANES sample with HF (37%). Results are shown in Table . Conclusions: Patients with HFpEF enrolled in clinical trials and those with HF in general population are significantly enriched with CKM components that may contribute to morbidity and mortality. Similar prevalence estimates were observed despite variability in trial inclusion criteria and heterogeneity in defining HFpEF and highlight CKM as a central target for HFpEF management.

BACKGROUND: Mechanisms of benefit with SGLT2is (sodium-glucose cotransporter-2 inhibitors) in heart failure (HF) remain incompletely characterized. Dapagliflozin alters ketone and fatty acid metabolism in HF with reduced ejection fraction though similar effects have not been observed in HF with preserved ejection fraction. We explore whether metabolic effects of SGLT2is vary across the left ventricular ejection fraction spectrum and their relationship with cardiometabolic end points in 2 randomized trials of dapagliflozin in HF. METHODS: Metabolomic profiling of 61 metabolites was performed in 527 participants from DEFINE-HF (Dapagliflozin Effects on Biomarkers, Symptoms and Functional Status in Patients With HF With Reduced Ejection Fraction) and PRESERVED-HF (Dapagliflozin in PRESERVED Ejection Fraction HF; 12-week, placebo-controlled trials of dapagliflozin in HF with reduced ejection fraction and HF with preserved ejection fraction, respectively). Linear regression was used to assess changes in principal components analysis–defined metabolite factors with treatment from baseline to 12 weeks, as well as the relationship between changes in metabolite clusters and HF-related end points. RESULTS: The mean age was 66±11 years, 43% were female, and 33% were self-identified as Black. Two principal components analysis–derived metabolite factors (which were comprised of ketone and short-/medium-chain acylcarnitines) increased with dapagliflozin compared with placebo. Ketosis (defined as 3-hydroxybutyrate >500 μM) was achieved in 4.5% with dapagliflozin versus 1.2% with placebo ( P =0.03). There were no appreciable treatment effects on amino acids, including branched-chain amino acids. Increases in several acylcarnitines were consistent across LVEF ( P interaction >0.10), whereas the ketogenic effect diminished at higher LVEF ( P interaction =0.01 for 3-hydroxybutyrate). Increases in metabolites reflecting mitochondrial dysfunction (particularly long-chain acylcarnitines) and aromatic amino acids and decreases in branched-chain amino acids were associated with worse HF-related outcomes in the overall cohort, with consistency across treatment and LVEF. CONCLUSIONS: SGLT2is demonstrate common (fatty acid) and distinct (ketogenic) metabolic signatures across the LVEF spectrum. Changes in key pathways related to fatty acid and amino acid metabolism are associated with HF-related end points and may serve as therapeutic targets across HF subtypes. REGISTRATION: URL: https://www.clinicaltrials.gov ; Unique Identifiers: NCT03030235 and NCT02653482.

Abstract Aims Compared with those without obesity, patients with obesity-related heart failure with preserved ejection fraction (HFpEF) have worse symptoms, haemodynamics, and outcomes. Current weight loss strategies (diet, drug, and surgical) work through decreased energy intake rather than increased expenditure and cause significant loss of skeletal muscle mass in addition to adipose tissue. This may have adverse implications for patients with HFpEF, who already have reduced skeletal muscle mass and function and high rates of physical frailty. Mitochondrial uncoupling agents may have unique beneficial effects by producing weight loss via increased catabolism rather than reduced caloric intake, thereby causing loss of adipose tissue while sparing skeletal muscle. HU6 is a controlled metabolic accelerator that is metabolized to the mitochondrial uncoupling agent 2,4-dinotrophenol. HU6 selectively increases carbon oxidation from fat and glucose while also decreasing toxic reactive oxygen species (ROS) production. In addition to sparing skeletal muscle loss, HU6 may have other benefits relevant to obesity-related HFpEF, including reduced specific tissue depots contributing to HFpEF; improved glucose utilization; and reduction in systemic inflammation via both decreased ROS production from mitochondria and decreased cytokine elaboration from excess, dysfunctional adipose. Methods We describe the rationale and design of HuMAIN-HFpEF, a Phase 2a randomized, double-blind, placebo-controlled, dose-titration, parallel-group trial in patients with obesity-related HFpEF to evaluate the effects of HU6 on weight loss, body composition, exercise capacity, cardiac structure and function, metabolism, and inflammation, and identify optimal dosage for future Phase 3 trials. Conclusions HuMAIN will test a promising novel agent for obesity-related HFpEF.

Abstract Background and Aims In the STEP-HFpEF trial programme, treatment with semaglutide resulted in multiple beneficial effects in patients with obesity-related heart failure with preserved ejection fraction (HFpEF). Efficacy may vary according to baseline diuretic use, and semaglutide treatment could modify diuretic dose. Methods In this pre-specified analysis of pooled data from the STEP-HFpEF and STEP-HFpEF-DM trials (n = 1145), which randomized participants with HFpEF and body mass index ≥ 30 kg/m2 to once weekly semaglutide 2.4 mg or placebo for 52 weeks, we examined whether efficacy and safety endpoints differed by baseline diuretic use, as well as the effect of semaglutide on loop diuretic use and dose changes over the 52-week treatment period. Results At baseline, across no diuretic (n = 220), non-loop diuretic only (n = 223), and loop diuretic [&lt;40 (n = 219), 40 (n = 309), and &gt;40 (n = 174) mg/day furosemide equivalents] groups, there was progressively higher prevalence of hypertension and atrial fibrillation; and greater severity of obesity and heart failure. Over 52 weeks of treatment, semaglutide had a consistent beneficial effect on change in body weight across diuretic use categories (adjusted mean difference vs. placebo ranged from −8.8% [95% confidence interval (CI) −10.3, −6.3] to −6.9% [95% CI −9.1, −4.7] from no diuretics to the highest loop diuretic dose category; interaction P = .39). Kansas City Cardiomyopathy Questionnaire clinical summary score improvement was greater in patients on loop diuretics compared to those not on loop diuretics (adjusted mean difference vs. placebo: +9.3 [6.5; 12.1] vs. +4.7 points [1.3, 8.2]; P = .042). Semaglutide had consistent beneficial effects on all secondary efficacy endpoints (including 6 min walk distance) across diuretic subgroups (interaction P = .24–.92). Safety also favoured semaglutide vs. placebo across the diuretic subgroups. From baseline to 52 weeks, loop diuretic dose decreased by 17% in the semaglutide group vs. a 2.4% increase in the placebo group (P &lt; .0001). Semaglutide (vs. placebo) was more likely to result in loop diuretic dose reduction (odds ratio [OR] 2.67 [95% CI 1.70, 4.18]) and less likely dose increase (OR 0.35 [95% CI 0.23, 0.53]; P &lt; .001 for both) from baseline to 52 weeks. Conclusions In patients with obesity-related HFpEF, semaglutide improved heart failure-related symptoms and physical limitations across diuretic use subgroups, with more pronounced benefits among patients receiving loop diuretics at baseline. Reductions in weight and improvements in exercise function with semaglutide vs. placebo were consistent in all diuretic use categories. Semaglutide also led to a reduction in loop diuretic use and dose between baseline and 52 weeks. Clinical Trial Registration NCT04788511 and NCT04916470.

Background: Sodium-glucose co-transport-2 (SGLT2) inhibitors have been shown to reduce clinical events and improve health status (symptoms, function, and quality of life) in patients with HF across the range of EF. Baseline kidney dysfunction is common in HF, complicates HF management, and is strongly linked to worse health status. Aim: The study objective was to assess whether the treatment effects of dapagliflozin on health status vary based on baseline eGFR. Methods: Patient-level data were pooled from the DEFINE-HF (N = 263 participants with EF < 40%) and PRESERVED-HF trials (N = 324 participants with EF > 45%). Both were double-blind, randomized trials of dapagliflozin vs. placebo, enrolling participants with NYHA class II or higher and elevated natriuretic peptides. The primary endpoint for this analysis was Kansas City Cardiomyopathy Questionnaire Clinical Summary Score (KCCQ-CCS) at 12 weeks. Interaction of dapagliflozin effects on KCCQ-CCS by baseline eGFR (mL/min/1.73m 2 ) was assessed as categorical (i.e., eGFR <60 vs. > 60) and continuous variables. Results: Across both trials there were 583 (99.3%) participants with available baseline eGFR. The median (25 th , 75 th ) eGFR was 59 (46,77). Dapagliflozin improved KCCQ-CSS at 12 weeks (placebo-adjusted difference, +5.0 points, 95% Confidence Interval [CI] 2.6-7.5; p-value <0.001), and this was consistent in participants with an eGFR > 60 (+6.0 points, 95% CI 2.4-9.7; p=0.001) and <60 (+4.1 points, 95% CI 0.5-7.7; p=0.025) (p-interaction = 0.46). The benefits of dapagliflozin on KCCQ-CSS were robust across eGFR when modeled continuously (p-interaction = 0.46) ( Figure ). There was no heterogeneity of treatment effects when analyzing other KCCQ domains based on eGFR categorically or continuously (all p-interaction = NS). Conclusion: Treatment with dapagliflozin for 12 weeks led to significant and consistent improvements in health-related quality of life in patients with HF across a wide range of eGFRs.