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Introduction: Reduced peak oxygen consumption (VO 2 ) is common and associated with adverse outcomes in patients with heart failure (HF) and preserved ejection fraction (HFpEF). According to the Fick principle, VO 2 is equal to the product of cardiac output (CO) and arterial-venous O 2 difference (AVO 2 diff). Patients with HFpEF display abnormalities each component, but no study has yet evaluated their prognostic impacts. Methods: Patients with HFpEF (n=501) and controls without HF (n=207) underwent invasive hemodynamic exercise testing with expired gas analysis and clinical follow up for the composite event of HF hospitalization or death. Results: Compared to controls, patients with HFpEF displayed slightly lower CO at rest with higher pulmonary capillary wedge pressure (PCWP). On exercise, subjects with HFpEF displayed blunted increases in CO and greater increase in PCWP (Figure A). As compared with controls, the slope of the increase in CO relative to VO 2 was lower in HFpEF (6.4 ± 3.3 vs 5.4 ± 3.2 L/L; P =0.0004), while augmentation in AVO 2 diff relative to VO 2 was greater in HFpEF (7.7 ± 5.4 vs 10.0 ± 5.6 min/dL; P <0.0001). Over a median 2.8 (1.1-4.6) years of follow up, 101 patients experienced the composite event. Patients with CO reserve below the median and increases in AVO 2 diff below median displayed higher risk of the composite endpoint (Figure B-C). After adjustments for age, sex, BMI, atrial fibrillation, LV mass, and EF, CO reserve remained strongly associated with the primary outcome (HR [95%CI] = 0.51 [0.38-0.68]; P <0.0001, per 1 SD increase) and the change of AVO 2 diff remained significant, but was less predictive (HR [95%CI] = 0.74 [0.60-0.92]; P =0.007, per 1 SD increase) in patients with HFpEF. Conclusions: Impaired ability to augment CO and peripheral O 2 delivery are associated with increasing risk of adverse events in HFpEF. Further study is required to identify therapeutic interventions targeting these hemodynamic perturbations to improve outcomes in HFpEF.

Introduction: Many patients with heart failure with preserved ejection fraction (HFpEF) display normal N-terminal-pro-B type natriuretic peptide (NTproBNP)levels. Mortality and hospitalization rates are lower in this group compared to patients with high NTproBNP, but it remains unclear whether these patients represent a fundamentally different phenotype or an earlier stage of disease. Methods: 213 subjects with HFpEF defined by invasive hemodynamics underwent serial echocardiographic examinations &gt;1 year apart. Clinical, cardiac structural, functional, and hemodynamic characteristics were examined. Results: Exam 2 was performed a median of 3.2 years (IQR 2.2-5.1) following Exam 1. From this cohort, 66 (33%) displayed normal NT-proBNP levels (≤125pg/ml, nBNP) and 147 (67%) displayed high NTproBNP (hBNP). Compared to hBNP, nBNP patients were younger (62±10 vs 71±9 years, p&lt;0.0001) and more obese (35±8 vs 32±7 kg/m 2 , p=0.005). At Exam 1, approximately 50% of nBNP displayed left ventricular (LV) systolic dysfunction defined as LV longitudinal strain (GLS)&lt;16% ( Figure A ) and LA dysfunction defined as left atrial (LA) reservoir strain&lt;26% ( Figure B ), but right ventricular (RV) systolic function as relatively preserved ( Figure C ). At Exam 2, LV, LA, and RV strain decreased in both groups (Panels A-C), with no difference between nBNP and hBNP in the velocity of change (p&gt;0.6 for all). More patients crossed the threshold definition for LV systolic and LA dysfunction in nBNP compared to hBNP ( Figure D and E ), but the prevalence of RV dysfunction increased more in hBNP ( Figure F ). Conclusions: In patients with HFpEF with normal NT-proBNP, biventricular systolic function and LA function deteriorate over time at similar pace. These data suggest that patients with HFpEF are not a fundamentally different disorder, but rather represent an earlier stage of disease that progresses from LV and LA dysfunction in early stages to RV dysfunction in advanced stages.

Introduction: Impaired left atrial (LA) function may limit optimal cardiac performance, reflecting both LA load and atrial dysfunction in HFpEF. The link between MRI-derived LA characteristics and exercise capacity in HFpEF has not been studied. Hypothesis: We hypothesized that total LA emptying fraction (LAEF) is reduced in HFpEF vs. healthy controls and LA functional impairment would be correlated with LV diastolic dysfunction, vascular dysfunction, and exercise intolerance. As LA hypertension may increase right ventricular load and limit increases in pulmonary perfusion with exercise, the correlation of LAEF with ventilatory efficiency (VE/VCO2 slope) was also examined. Methods: Baseline exercise, echo, and cardiac MRI data from RELAX (a study of sildenafil in HFpEF) in patients in sinus rhythm with a measureable LAEF by MRI (n=100) were utilized. Healthy volunteers (n=21) were included for comparison. LAV was measured by the biplane area-length method using 2-/4-chamber SSFP CMR. LAEF was defined as total (ΔLAVmax-min), passive/conduit (ΔLAVmax-before atrial contraction ), and active (ΔLAVbefore atrial contraction-min), each divided by maximal LAV. Results: As compared to controls, LAEF (particularly passive conduit function) was reduced in HFpEF (Table 1). In HFpEF, patients with lower LAEF had a larger LA, more echo diastolic dysfunction, higher PA systolic pressure and NT-proBNP, reduced aortic distensibility, worse exercise capacity, and ventilatory inefficiency (Table 2). Conclusions: LA function is impaired in HFpEF, may serve as a marker of chronic LA hypertension and may contribute to impaired exercise intolerance and ventilatory inefficiency.

Introduction: In vitro, ST2 is a marker of myocyte stress and inflammation but in vivo, there is no trans-cardiac ST2 concentration step-up to support cardiac ST2 activation in human heart failure (HF) calling into question the source of ST2 in HF. While ST2 is predictive of adverse outcomes in HF, the relationship between ST2 and key pathophysiologic domains in HF with preserved ejection fraction (HFpEF) is not well characterized. Hypothesis: ST2 levels increase in proportion to the severity of left ventricular (LV) remodeling and dysfunction in HFpEF. Methods: At enrollment, patients (n=174) from the RELAX trial testing sildenafil in HFpEF had serum ST2 levels measured and underwent assessment of pathophysiologic domains including congestion, cardiac structure and function, exercise performance (peak oxygen consumption (VO2)) and biomarkers of neurohumoral activation (NT-proBNP, aldosterone, endothelin-1), renal dysfunction (cystatin-C), fibrosis (pro-collagen III N-terminal peptide [NTP], C-telopeptide for type I collagen [CITP]), inflammation (high-sensitivity CRP [hsCRP]) and myocardial necrosis (high-sensitivity troponin-I [hsTnI]). Analysis adjusted for sex, a covariate associated with ST2 levels in normal persons. Results: See table. ST2 was associated with greater congestion, worse right ventricular (RV) pressure overload and dysfunction, lower peak VO2 and biomarkers of neurohumoral activation, renal dysfunction, fibrosis and myocardial necrosis and tended to be associated with systemic inflammation (hsCRP). ST2 was not associated with LV structure or LV systolic or diastolic function. Conclusions: In HFpEF, ST2 was associated with measures of right sided congestion, RV overload and dysfunction, exercise intolerance and other systemic markers of more advanced HF but not with LV structure or LV systolic or diastolic function. These data suggest that mechanisms distinct from LV stress stimulate ST2 activation in HFpEF.

Abstract Pulmonary hypertension (PH) associated with left heart failure (LHF) (PH-LHF) is one of the most common causes of PH. It directly contributes to symptoms and reduced functional capacity and negatively affects right heart function, ultimately leading to a poor prognosis. There are no specific treatments for PH-LHF, despite the high number of drugs tested so far. This scientific document addresses the main knowledge gaps in PH-LHF with emphasis on pathophysiology and clinical trials. Key identified issues include better understanding of the role of pulmonary venous versus arteriolar remodelling, multidimensional phenotyping to recognize patient subgroups positioned to respond to different therapies, and conduct of rigorous pre-clinical studies combining small and large animal models. Advancements in these areas are expected to better inform the design of clinical trials and extend treatment options beyond those effective in pulmonary arterial hypertension. Enrichment strategies, endpoint assessments, and thorough haemodynamic studies, both at rest and during exercise, are proposed to play primary roles to optimize early-stage development of candidate therapies for PH-LHF.

Importance Although the results of A Study to Evaluate the Corvia Medical Inc IASD System II to Reduce Elevated Left Atrial Pressure in Patients with Heart Failure (REDUCE LAP-HF II) trial were neutral overall, atrial shunt therapy demonstrated potential efficacy in responders (no latent pulmonary vascular disease and no cardiac rhythm management device). Post hoc analyses were conducted to evaluate the effect of shunt vs sham stratified by responder status. Objective To evaluate the effect of atrial shunt vs sham control on cardiac structure/function in the overall study and stratified by responder status. Design, Setting, and Participants This was a sham-controlled randomized clinical trial of an atrial shunt device in heart failure with preserved ejection fraction (HFpEF)/HF with mildly reduced EF (HFmrEF). Trial participants with evaluable echocardiography scans were recruited from 89 international medical centers. Data were analyzed from April 2023 to January 2024. Interventions Atrial shunt device or sham control. Main Outcome Measures Changes in echocardiographic measures from baseline to 1, 6, 12, and 24 months after index procedure. Results The modified intention-to-treat analysis of the REDUCE LAP-HF II trial included 621 randomized patients (median [IQR] age, 72.0 [66.0-77.0] years; 382 female [61.5%]; shunt arm, 309 [49.8%]; sham control arm, 312 [50.2%]). Through 24 months, 212 of 217 patients (98%) in the shunt arm with evaluable echocardiograms had patent shunts. In the overall trial population, the shunt reduced left ventricular (LV) end-diastolic volume (mean difference, −5.65 mL; P &amp;lt;.001), left atrial (LA) minimal volume (mean difference, −2.8 mL; P =.01), and improved LV systolic tissue Doppler velocity (mean difference, 0.69 cm/s; P &amp;lt;.001) and LA emptying fraction (mean difference, 1.88 percentage units; P =.02) compared with sham. Shunt treatment also increased right ventricular (RV; mean difference, 9.58 mL; P &amp;lt;.001) and right atrial (RA; mean difference, 9.71 mL; P &amp;lt;.001) volumes but had no effect on RV systolic function, pulmonary artery pressure, or RA pressure compared with sham. In the shunt arm, responders had smaller increases in RV end-diastolic volume (mean difference, 5.71 mL vs 15.18 mL; interaction P =.01), RV end-systolic volume (mean difference, 1.58 mL vs 7.89 mL; interaction P =.002), and RV/LV ratio (mean difference, 0.07 vs 0.20; interaction P &amp;lt;.001) and larger increases in transmitral A wave velocity (mean difference, 5.08 cm/s vs −1.97 cm/s; interaction P =.02) compared with nonresponders randomized to the shunt, suggesting greater ability to accommodate shunted blood through the pulmonary circulation enabling LA unloading. Conclusions and Relevance In this post hoc analysis of the REDUCE LAP-HF II trial, over 2 years of follow-up, atrial shunting led to reverse remodeling of left-sided chambers and increases in volume of right-sided chambers consistent with the shunt flow but no change in RV systolic function compared with sham. Changes in cardiac structure/function were more favorable in responders compared with nonresponders treated with the shunt, supporting the previously identified responder group hypothesis and mechanism, although further evaluation with longer follow-up is needed. Trial Registration ClinicalTrials.gov Identifier: NCT03088033

BACKGROUND: Heart failure triggers a shift in myocardial metabolic substrate utilization, favoring the ketone body 3-hydroxybutyrate as energy source. We hypothesized that 14-day treatment with ketone ester (KE) would improve resting and exercise hemodynamics and exercise capacity in patients with heart failure with reduced ejection fraction. METHODS: In a randomized, double-blind cross-over study, nondiabetic patients with heart failure with reduced ejection fraction received 14-day KE and 14-day isocaloric non-KE comparator regimens of 4 daily doses separated by a 14-day washout period. After each treatment period, participants underwent right heart catheterization, echocardiography, and blood sampling at plasma trough levels and after dosing. Participants underwent an exercise hemodynamic assessment after a second dosing. The primary end point was resting cardiac output (CO). Secondary end points included resting and exercise pulmonary capillary wedge pressure and peak exercise CO and metabolic equivalents. RESULTS: We included 24 patients with heart failure with reduced ejection fraction (17 men; 65±9 years of age; all White). Resting CO at trough levels was higher after KE compared with isocaloric comparator (5.2±1.1 L/min versus 5.0±1.1 L/min; difference, 0.3 L/min [95% CI, 0.1–0.5), and pulmonary capillary wedge pressure was lower (8±3 mm Hg versus 11±3 mm Hg; difference, −2 mm Hg [95% CI, −4 to −1]). These changes were amplified after KE dosing. Across all exercise intensities, KE treatment was associated with lower mean exercise pulmonary capillary wedge pressure (−3 mm Hg [95% CI, −5 to −1] ) and higher mean CO (0.5 L/min [95% CI, 0.1–0.8]), significantly different at low to moderate steady-state exercise but not at peak. Metabolic equivalents remained similar between treatments. In exploratory analyses, KE treatment was associated with 18% lower NT-proBNP (N-terminal pro-B-type natriuretic peptide; difference, −98 ng/L [95% CI, −185 to −23]), higher left ventricular ejection fraction (37±5 versus 34±5%; P =0.01), and lower left atrial and ventricular volumes. CONCLUSIONS: KE treatment for 14 days was associated with higher CO at rest and lower filling pressures, cardiac volumes, and NT-proBNP levels compared with isocaloric comparator. These changes persisted during exercise and were achieved on top of optimal medical therapy. Sustained modulation of circulating ketone bodies is a potential treatment principle in patients with heart failure with reduced ejection fraction. REGISTRATION: URL: https://www.clinicaltrials.gov ; Unique identifier: NCT05161650.

Abstract Aims The determinants and relevance of right ventricular (RV) mechanical dyssynchrony in heart failure with reduced ejection fraction (HFrEF) are poorly understood. We hypothesized that increased afterload may adversely affect the synchrony of RV contraction. Methods and results A total of 148 patients with HFrEF and 36 controls underwent echocardiography, right heart catheterization, and gated single-photon emission computed tomography to measure RV chamber volumes and mechanical dyssynchrony (phase standard deviation of systolic displacement timing). Exams were repeated after preload (N = 135) and afterload (N = 15) modulation. Patients with HFrEF showed higher RV dyssynchrony compared with controls (40.6 ± 17.5° vs. 27.8 ± 9.1°, P &lt; 0.001). The magnitude of RV dyssynchrony in HFrEF correlated with larger RV and left ventricular (LV) volumes, lower RV ejection fraction (RVEF) and LV ejection fraction, reduced intrinsic contractility, increased heart rate, higher pulmonary artery (PA) load, and impaired RV–PA coupling (all P ≤ 0.01). Low RVEF was the strongest predictor of RV dyssynchrony. Left bundle branch block (BBB) was associated with greater RV dyssynchrony than right BBB, regardless of QRS duration. RV afterload reduction by sildenafil improved RV dyssynchrony (P = 0.004), whereas preload change with passive leg raise had modest effect. Patients in the highest tertiles of RV dyssynchrony had an increased risk of adverse clinical events compared with those in the lower tertile [T2/T3 vs. T1: hazard ratio 1.98 (95% confidence interval 1.20–3.24), P = 0.007]. Conclusions RV dyssynchrony is associated with RV remodelling, dysfunction, adverse haemodynamics, and greater risk for adverse clinical events. RV dyssynchrony is mitigated by acute RV afterload reduction and could be a potential therapeutic target to improve RV performance in HFrEF.