Exercise intolerance in patients with heart failure and preserved left ventricular systolic function: failure of the Frank-Starling mechanism

Percent Predicted Peak Exercise Oxygen Pulse Provides Insights Into Ventricular-Vascular Response and Prognosticates HFpEF

Background

Peak oxygen consumption and oxygen pulse along with their respective percent predicted measures are gold standards of exercise capacity. To date, no studies have investigated the relationship between percent predicted peak oxygen pulse (%PredO2P) and ventricular-vascular response (VVR) and the association of %PredO2P with all-cause mortality in heart failure with preserved ejection fraction (HFpEF) patients.

Objectives

The authors investigated the association between: 1) CPET measures of %PredO2P and VVR; and 2) %PredO2P and all-cause mortality in HFpEF patients.

Methods

Our cohort of 154 HFpEF patients underwent invasive CPET and were grouped into %PredO2P tertiles. The association between percent predicted Fick components and markers of VVR (ie, proportionate pulse pressure, effective arterial elastance) was determined with correlation analysis. The Cox proportional hazards model was used to identify predictors of mortality.

Results

The participants' mean age was 57 ± 15 years. Higher %PredO2P correlated with higher exercise capacity. In terms of VVR, higher %PredO2P correlated with a lower pressure for a given preload (effective arterial elastance r = -0.45, P < 0.001 and proportionate pulse pressure r = -0.22, P = 0.008). %PredO2P distinguished normal and abnormal percent predicted peak stroke volume and correlated positively with %PredVO2 (r = 0.61, P < 0.001). Participants had a median follow-up time of 5.6 years and 15% death. Adjusted for age and body mass index, there was a 5% relative reduction in mortality (HR: 0.95, 95% CI: 0.92-0.98, P = 0.003) for every percent increase in %PredO2P.

Conclusions

In HFpEF, %PredO2P is a VVR marker that can stratify invasive parameters such as percent predicted peak stroke volume. %PredO2P is an independent prognostic marker for all-cause mortality and those with higher %PredO2P exhibited longer survival.

Exercise training for patients with heart failure and preserved ejection fraction. A narrative review

Heart failure with preserved ejection fraction (HFpEF) remains a significant global health challenge, accounting for up to 50% of all heart failure cases and predominantly affecting the elderly and women. Despite advancements in therapeutic strategies, HFpEF's complexity poses substantial challenges in management, particularly due to its high comorbidity burden, including renal failure, atrial fibrillation, and obesity, among others. These comorbidities not only complicate the pathophysiology of HFpEF but also exacerbate its symptoms, necessitating a personalized approach to treatment focused on comorbidity management and symptom alleviation. In heart failure with reduced ejection fraction, exercise training (ET) was effective in improving exercise tolerance, quality of life, and reducing hospitalizations. However, the efficacy of ET in HFpEF patients remains less understood, with limited studies showing mixed results. Exercise intolerance is a key symptom in HFpEF patients, and it has a multifactorial origin since both central and peripheral oxygen mechanisms of transport and utilization are often compromised. Recent evidence underscores the potential of supervised ET in enhancing exercise tolerance and quality of life among HFpEF patients; however, the literature remains sparse and predominantly consists of small-scale studies. This review highlights the critical role of exercise intolerance in HFpEF and synthesizes current knowledge on the benefits of ET. It also calls for a deeper understanding and further research into exercise-based interventions and their underlying mechanisms, emphasizing the need for larger, well-designed studies to evaluate the effectiveness of ET in improving outcomes for HFpEF patients.

α-Adrenergic regulation of skeletal muscle blood flow during exercise in patients with heart failure with preserved ejection fraction

Heart failure with preserved ejection fraction (HFpEF) has been characterized by lower blood flow to exercising limbs and lower peak oxygen utilization (V ̇ O 2 ${{\dot{V}}_{{{{\mathrm{O}}}_{\mathrm{2}}}}}$ ), possibly associated with disease-related changes in sympathetic (α-adrenergic) signaling. Thus, in seven patients with HFpEF (70 ± 6 years, 3 female/4 male) and seven controls (CON) (66 ± 3 years, 3 female/4 male), we examined changes (%Δ) in leg blood flow (LBF, Doppler ultrasound) and legV ̇ O 2 ${{\dot{V}}_{{{{\mathrm{O}}}_{\mathrm{2}}}}}$ to intra-arterial infusion of phentolamine (PHEN, α-adrenergic antagonist) or phenylephrine (PE, α1-adrenergic agonist) at rest and during single-leg knee-extension exercise (0, 5 and 10 W). At rest, the PHEN-induced increase in LBF was not different between groups, but PE-induced reductions in LBF were lower in HFpEF (-16% ± 4% vs. -26% ± 5%, HFpEF vs. CON; P < 0.05). During exercise, the PHEN-induced increase in LBF was greater in HFpEF at 10 W (16% ± 8% vs. 8% ± 5%; P < 0.05). PHEN increased legV ̇ O 2 ${{\dot{V}}_{{{{\mathrm{O}}}_{\mathrm{2}}}}}$ in HFpEF (10% ± 3%, 11% ± 6%, 15% ± 7% at 0, 5 and 10 W; P < 0.05) but not in controls (-1% ± 9%, -4% ± 2%, -1% ± 5%; P = 0.24). The 'magnitude of sympatholysis' (PE-induced %Δ LBF at rest - PE-induced %Δ LBF during exercise) was lower in patients with HFpEF (-6% ± 4%, -6% ± 6%, -7% ± 5% vs. -13% ± 6%, -17% ± 5%, -20% ± 5% at 0, 5 and 10 W; P < 0.05) and was positively related to LBF, leg oxygen delivery, legV ̇ O 2 ${{\dot{V}}_{{{{\mathrm{O}}}_{\mathrm{2}}}}}$ , and the PHEN-induced increase in LBF (P < 0.05). Together, these data indicate that excessive α-adrenergic vasoconstriction restrains blood flow and limitsV ̇ O 2 ${{\dot{V}}_{{{{\mathrm{O}}}_{\mathrm{2}}}}}$ of the exercising leg in patients with HFpEF, and is related to impaired functional sympatholysis in this patient group. KEY POINTS: Sympathetic (α-adrenergic)-mediated vasoconstriction is exaggerated during exercise in patients with heart failure with preserved ejection fraction (HFpEF), which may contribute to limitations of blood flow, oxygen delivery and oxygen utilization in the exercising muscle. The ability to adequately attenuate α1-adrenergic vasoconstriction (i.e. functional sympatholysis) within the vasculature of the exercising muscle is impaired in patients with HFpEF. These observations extend our current understanding of HFpEF pathophysiology by implicating excessive α-adrenergic restraint and impaired functional sympatholysis as important contributors to disease-related impairments in exercising muscle blood flow and oxygen utilization in these patients.

Distinctive left ventricular-arterial and right ventricular-pulmonary arterial coupling observed in patients with heart failure and a higher left ventricular ejection fraction range

AIMS

Higher left ventricular (LV) ejection fraction (EF) is related to unfavourable prognosis in patients with heart failure (HF) with preserved ejection fraction (HFpEF). The cause of this finding needs to be haemodynamically explained. Thus, we investigated this crucial issue from the perspective of LV-arterial (A) and right ventricular (RV)-pulmonary arterial (PA) coupling.

METHODS AND RESULTS

Study patients were derived from our prospective cohort study of patients hospitalized due to acute decompensated HF and LVEF > 40%. We divided the 255 patients into three groups: HF with mildly reduced EF (HFmrEF), HFpEF with 50% ≤ LVEF < 60%, and HFpEF with LVEF ≥ 60%. We compared LV end-systolic elastance (Ees), effective arterial elastance (Ea), and Ees/Ea as a representative of LV-A coupling among groups and compared the ratio of tricuspid annular plane excursion to peak pulmonary arterial systolic pressure (TAPSE/PASP) as a representative of RV-PA coupling. All-cause death and readmission due to HF-free survival was worse in the group with a higher LVEF range. Ees/Ea was greater in HFpEF patients with LVEF ≥ 60% (2.12 ± 0.57) than in those with 50% ≤ LVEF < 60% (1.20 ± 0.14) and those with HFmrEF (0.82 ± 0.09) (P < 0.001). PASP was increased in the groups with higher LVEF; however, TAPSE/PASP did not differ among groups (n = 168, P = 0.17). In a multivariate Cox proportional hazard model, TAPSE/PASP but not PASP was significantly related to event-free survival independent of LVEF.

CONCLUSION

HFpEF patients with higher LVEF have unfavourable prognosis and distinctive LV-A coupling: Ees/Ea is elevated up to 2.0 or more. Impaired RV-PA coupling also worsens prognosis in such patients.

CLINICAL TRIAL REGISTRATION

URL: https://www.umin.ac.jp/ctr/index.htm Unique identifier: UMIN000017725.

Supervised exercise training in heart failure with preserved ejection fraction: A systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Heart failure with preserved ejection fraction (HFpEF) represents a prevalent and increasingly common condition. Recognized for its high incidence, there is a growing interest in exploring effective interventions, with exercise emerging as a critical component in the rehabilitation of HFpEF patients. We aim to update evidence on the impact of supervised exercise training on exercise capacity, diastolic function, arterial stiffness, and health-related quality of life (QoL) of individuals diagnosed with HFpEF.

METHODS

We systematically reviewed the literature, searching from inception to December 2023, utilizing databases such as MEDLINE (via PubMed), Google Scholar, the Cochrane Library, ClinicalTrials.gov, and the ScienceDirect portal. Statistical analyses utilized RevMan 5.4 with a random-effects model. Outcomes were presented as the weighted mean difference (WMD) alongside corresponding 95 % confidence intervals (CI), and heterogeneity was assessed using the I2 test.

RESULTS

Our final analysis included 7 randomized controlled trials (RCTs) of 346 participants, with an exercise follow-up duration of 12 to 48 weeks. In our pooled analysis, diastolic function, measured by E/A (WMD 0.01, 95 % CI: -0.04 to 0.05, p = 0.79; I2 = 0 %) and E/e' (WMD 0.87, 95 % CI: -11.09 to 12.83, p = 0.89; I2 = 69 %), showed no significant change post-exercise training. However, exercise capacity, measured by peak V̇o2 significantly improved (WMD 2.57, 95 % CI: 1.38 to 3.75, p < 0.0001; I2= 14 %). The QoL assessed by the Minnesota Living with Heart Failure (MLWHF) score remained unchanged (WMD -3.12, 95 % CI: -8.73 to 2.50, p = 0.28; I2 = 0 %), but the SF-36 physical functioning scale indicated significant improvement (WMD 9.84, 95 % CI: 2.94 to 16.73, p < 0.005; I2 = 0 %). Arterial stiffness and vascular function remained unaffected, as evidenced by arterial elastance (WMD -0.13, 95 % CI: -0.36 to 0.10, p = 0.26; I2 = 0 %) and total arterial compliance (WMD 0.12, 95 % CI: -0.26 to 0.49, p = 0.54; I2 = 0 %).

CONCLUSION

Exercise training is safe and significantly enhances exercise capacity and QoL in HFpEF, with no significant impact on diastolic function, arterial stiffness, or vascular function.

Effects of aging and endurance exercise training on cardiorespiratory fitness and cardiac structure and function in healthy midlife and older women

Cardiovascular disease (CVD) remains the leading cause of morbidity and mortality in women in developed societies. Unfavorable structural and functional adaptations within the heart and central blood vessels with sedentary aging in women can act as the substrate for the development of debilitating CVD conditions such as heart failure with preserved ejection fraction (HFpEF). The large decline in cardiorespiratory fitness, as indicated by maximal or peak oxygen uptake (V̇o2max and V̇o2peak, respectively), that occurs in women as they age significantly affects their health and chronic disease status, as well as the risk of cardiovascular and all-cause mortality. Midlife and older women who have performed structured endurance exercise training for several years or decades of their adult lives exhibit a V̇o2max and cardiac and vascular structure and function that are on par or even superior to much younger sedentary women. Therefore, regular endurance exercise training appears to be an effective preventative strategy for mitigating the adverse physiological cardiovascular adaptations associated with sedentary aging in women. Herein, we narratively describe the aging and short- and long-term endurance exercise training adaptations in V̇o2max, cardiac structure, and left ventricular systolic and diastolic function at rest and exercise in midlife and older women. The role of circulating estrogens on cardiac structure and function is described for consideration in the timing of exercise interventions to maximize beneficial adaptations. Current research gaps and potential areas for future investigation to advance our understanding in this critical knowledge area are highlighted.

Evidence of impaired functional sympatholysis in patients with heart failure with preserved ejection fraction

Exercising muscle blood flow is reduced in patients with heart failure with a preserved ejection fraction (HFpEF), which may be related to disease-related changes in the ability to overcome sympathetic nervous system (SNS)-mediated vasoconstriction during exercise, (i.e., "functional sympatholysis"). Thus, in 12 patients with HFpEF (69 ± 7 yr) and 11 healthy controls (Con, 69 ± 4 yr), we examined forearm blood flow (FBF), mean arterial pressure (MAP), and forearm vascular conductance (FVC) during rhythmic handgrip exercise (HG) at 30% of maximum voluntary contraction with or without lower-body negative pressure (LBNP, -20 mmHg) to increase SNS activity and elicit peripheral vasoconstriction. SNS-mediated vasoconstrictor responses were determined as LBNP-induced changes (%Δ) in FVC, and the "magnitude of sympatholysis" was calculated as the difference between responses at rest and during exercise. At rest, the LBNP-induced change in FVC was significantly lesser in HFpEF compared with Con (HFpEF: -9.5 ± 5.5 vs. Con: -21.0 ± 8.0%; P < 0.01). During exercise, LBNP-induced %ΔFVC was significantly attenuated in Con compared with rest (HG: -5.8 ± 6.0%; P < 0.05) but not in HFpEF (HG: -9.9 ± 2.5%; P = 0.88). Thus, the magnitude of sympatholysis was lesser in HFpEF compared with Con (HFpEF: 0.4 ± 4.7 vs. Con: -15.2 ± 11.8%; P < 0.01). These data demonstrate a diminished ability to attenuate SNS-mediated vasoconstriction in HFpEF and provide new evidence suggesting impaired functional sympatholysis in this patient group.NEW & NOTEWORTHY Data from the current study suggest that functional sympatholysis, or the ability to adequately attenuate sympathetic nervous system (SNS)-mediated vasoconstriction during exercise, is impaired in patients with heart failure with preserved ejection fraction (HFpEF). These observations extend the current understanding of HFpEF pathophysiology by implicating inadequate functional sympatholysis as an important contributor to reduced exercising muscle blood flow in this patient group.

Reducing Pulmonary Capillary Wedge Pressure During Exercise Exacerbates Exertional Dyspnea in Patients With Heart Failure With Preserved Ejection Fraction: Implications for V˙/Q˙ Mismatch

BACKGROUND

The primary cause of dyspnea on exertion in heart failure with preserved ejection fraction (HFpEF) is presumed to be the marked rise in pulmonary capillary wedge pressure during exercise; however, this hypothesis has never been tested directly. Therefore, we evaluated invasive exercise hemodynamics and dyspnea on exertion in patients with HFpEF before and after acute nitroglycerin (NTG) treatment to lower pulmonary capillary wedge pressure.

RESEARCH QUESTION

Does reducing pulmonary capillary wedge pressure during exercise with NTG improve dyspnea on exertion in HFpEF?

STUDY DESIGN AND METHODS

Thirty patients with HFpEF performed two invasive 6-min constant-load cycling tests (20 W): one with placebo (PLC) and one with NTG. Ratings of perceived breathlessness (0-10 scale), pulmonary capillary wedge pressure (right side of heart catheter), and arterial blood gases (radial artery catheter) were measured. Measurements of V˙/Q˙ matching, including alveolar dead space (Vdalv; Enghoff modification of the Bohr equation) and the alveolar-arterial Po2 difference (A-aDO2; alveolar gas equation), were also derived. The ventilation (V˙e)/CO2 elimination (V˙co2) slope was also calculated as the slope of the V˙e and V˙co2 relationship, which reflects ventilatory efficiency.

RESULTS

Ratings of perceived breathlessness increased (PLC: 3.43 ± 1.94 vs NTG: 4.03 ± 2.18; P = .009) despite a clear decrease in pulmonary capillary wedge pressure at 20 W (PLC: 19.7 ± 8.2 vs NTG: 15.9 ± 7.4 mm Hg; P < .001). Moreover, Vdalv (PLC: 0.28 ± 0.07 vs NTG: 0.31 ± 0.08 L/breath; P = .01), A-aDO2 (PLC: 19.6 ± 6.7 vs NTG: 21.1 ± 6.7; P = .04), and V˙e/V˙co2 slope (PLC: 37.6 ± 5.7 vs NTG: 40.2 ± 6.5; P < .001) all increased at 20 W after a decrease in pulmonary capillary wedge pressure.

INTERPRETATION

These findings have important clinical implications and indicate that lowering pulmonary capillary wedge pressure does not decrease dyspnea on exertion in patients with HFpEF; rather, lowering pulmonary capillary wedge pressure exacerbates dyspnea on exertion, increases V˙/Q˙ mismatch, and worsens ventilatory efficiency during exercise in these patients. This study provides compelling evidence that high pulmonary capillary wedge pressure is likely a secondary phenomenon rather than a primary cause of dyspnea on exertion in patients with HFpEF, and a new therapeutic paradigm is needed to improve symptoms of dyspnea on exertion in these patients.

Impact of heart rate, aortic compliance and stroke volume on the aortic regurgitation fraction studied in an ex vivo pig model

INTRODUCTION

Drug therapy to reduce the regurgitation fraction (RF) of high-grade aortic regurgitation (AR) by increasing heart rate (HR) is generally recommended. However, chronic HR reduction in HFREF patients can significantly improve aortic compliance and thereby potentially decrease RF. To clarify these contrasts, we examined the influence of HR, aortic compliance and stroke volume (SV) on RF in an ex vivo porcine model of severe AR.

METHODS

Experiments were performed on porcine ascending aorta with aortic valves (n=12). Compliance was varied by inserting a Dacron graft close to the aortic valve. Both tube systems were connected to a left heart simulator varying HR and SV. AR was accomplished by punching a 0.3 cm2 hole in one aortic cusp. Flow, RF, SV and aortic pressure were measured, aortic compliance with transoesophageal ultrasound probes.

RESULTS

Compliance of the aorta was significantly reduced after Dacron graft insertion (0.55%±0.21%/mm Hg vs 0.01%±0.007%/mm Hg, p<0.001, respectively). With increasing HR, RF was significantly reduced in each steady state of the native aorta (HR 40 bpm: 88%±7% vs HR 120 bpm: 42%±10%; p<0.001), but Dacron tube did not affect RF (HR 40 bpm: 87%±8%; p=0.79; HR 120 bpm: 42%±3%; p=0.86). Increasing SV also reduced RF independent of the stiff Dacron graft.

CONCLUSION

Aortic compliance did not affect AR in the ex vivo porcine model of AR. RF was significantly reduced with increasing HR and SV. These results affirm that HR lowering and negative inotropic drugs should be avoided to treat severe AR.

Pulmonary Hypertension in Left Heart Diseases: Pathophysiology, Hemodynamic Assessment and Therapeutic Management

Pulmonary hypertension (PH) associated with left heart diseases (PH-LHD), also termed group 2 PH, represents the most common form of PH. It develops through the passive backward transmission of elevated left heart pressures in the setting of heart failure, either with preserved (HFpEF) or reduced (HFrEF) ejection fraction, which increases the pulsatile afterload of the right ventricle (RV) by reducing pulmonary artery (PA) compliance. In a subset of patients, progressive remodeling of the pulmonary circulation resulted in a pre-capillary phenotype of PH, with elevated pulmonary vascular resistance (PVR) further increasing the RV afterload, eventually leading to RV-PA uncoupling and RV failure. The primary therapeutic objective in PH-LHD is to reduce left-sided pressures through the appropriate use of diuretics and guideline-directed medical therapies for heart failure. When pulmonary vascular remodeling is established, targeted therapies aiming to reduce PVR are theoretically appealing. So far, such targeted therapies have mostly failed to show significant positive effects in patients with PH-LHD, in contrast to their proven efficacy in other forms of pre-capillary PH. Whether such therapies may benefit some specific subgroups of patients (HFrEF, HFpEF) with specific hemodynamic phenotypes (post- or pre-capillary PH) and various degrees of RV dysfunction still needs to be addressed.

Ventricular stiffening and chamber contracture in heart failure with higher ejection fraction

AIMS

Ancillary analyses from clinical trials have suggested reduced efficacy for neurohormonal antagonists among patients with heart failure and preserved ejection fraction (HFpEF) and higher ranges of ejection fraction (EF).

METHODS AND RESULTS

A total of 621 patients with HFpEF were grouped into those with low-normal left ventricular EF (LVEF) (HFpEF<65% , n = 319, 50% ≤ LVEF <65%) or HFpEF≥65% (n = 302, LVEF ≥65%), and compared with 149 age-matched controls undergoing comprehensive echocardiography and invasive cardiopulmonary exercise testing. A sensitivity analysis was performed in a second non-invasive community-based cohort of patients with HFpEF (n = 244) and healthy controls without cardiovascular disease (n = 617). Patients with HFpEF≥65% had smaller left ventricular (LV) end-diastolic volume than HFpEF<65% , but LV systolic function assessed by preload recruitable stroke work and stroke work/end-diastolic volume was similarly impaired. Patients with HFpEF≥65% displayed an end-diastolic pressure-volume relationship (EDPVR) that was shifted leftward, with increased LV diastolic stiffness constant β, in both invasive and community-based cohorts. Cardiac filling pressures and pulmonary artery pressures at rest and during exercise were similarly abnormal in all EF subgroups. While patients HFpEF≥57% displayed leftward shifted EDPVR, those with HFpEF<57% had a rightward shifted EDPVR more typical of heart failure with reduced EF.

CONCLUSION

Most pathophysiologic differences in patients with HFpEF and higher EF are related to smaller heart size, increased LV diastolic stiffness, and leftward shift in the EDPVR. These findings may help to explain the absence of efficacy for neurohormonal antagonists in this group and raise a new hypothesis, that interventions to stimulate eccentric LV remodelling and enhance diastolic capacitance may be beneficial for patients with HFpEF and EF in the higher range.

Sarcomere length affects Ca2+ sensitivity of contraction in ischemic but not non-ischemic myocardium

In healthy hearts, myofilaments become more sensitive to Ca2+ as the myocardium is stretched. This effect is known as length-dependent activation and is an important cellular-level component of the Frank-Starling mechanism. Few studies have measured length-dependent activation in the myocardium from failing human hearts. We investigated whether ischemic and non-ischemic heart failure results in different length-dependent activation responses at physiological temperature (37°C). Myocardial strips from the left ventricular free wall were chemically permeabilized and Ca2+-activated at sarcomere lengths (SLs) of 1.9 and 2.3 µm. Data were acquired from 12 hearts that were explanted from patients receiving cardiac transplants; 6 had ischemic heart failure and 6 had non-ischemic heart failure. Another 6 hearts were obtained from organ donors. Maximal Ca2+-activated force increased at longer SL for all groups. Ca2+ sensitivity increased with SL in samples from donors (P < 0.001) and patients with ischemic heart failure (P = 0.003) but did not change with SL in samples from patients with non-ischemic heart failure. Compared with donors, troponin I phosphorylation decreased in ischemic samples and even more so in non-ischemic samples; cardiac myosin binding protein-C (cMyBP-C) phosphorylation also decreased with heart failure. These findings support the idea that troponin I and cMyBP-C phosphorylation promote length-dependent activation and show that length-dependent activation of contraction is blunted, yet extant, in the myocardium from patients with ischemic heart failure and further reduced in the myocardium from patients with non-ischemic heart failure. Patients who have a non-ischemic disease may exhibit a diminished contractile response to increased ventricular filling.

Unfavourable outcomes in patients with heart failure with higher preserved left ventricular ejection fraction

AIMS

Newly introduced drugs for heart failure (HF) have been reported to improve the prognosis of HF with preserved ejection fraction (HFpEF) in the lower range of left ventricular ejection fraction (LVEF). We hypothesized that a higher LVEF is related to an unfavourable prognosis in patients with HFpEF.

METHODS AND RESULTS

We tested this hypothesis by analysing the data from a prospective multicentre cohort study in 255 patients admitted to the hospital due to decompensated HF (LVEF > 40% at discharge). The primary endpoint of this study was a composite outcome of all-cause death and readmission due to HF, and the secondary endpoint was readmission due to HF. LVEF and the mitral E/e' ratio were measured using echocardiography. In multicovariate parametric survival time analysis, LVEF [hazard ratio (HR) = 1.046 per 1% increase, P = 0.001], concurrent atrial fibrillation (AF) (HR = 3.203, P < 0.001), and E/e' (HR = 1.083 per 1.0 increase, P < 0.001) were significantly correlated with the primary endpoint. In addition to these covariates, angiotensin-converting enzyme inhibitor (ACEI)/angiotensin receptor blocker (ARB) use was significantly correlated with the secondary endpoint (HR = 0.451, P = 0.008). Diagnostic performance plot analysis demonstrated that the discrimination threshold value for LVEF that could identify patients prone to reaching the primary endpoint was ≥57.2%. The prevalence of AF or E/e' ratio did not differ significantly between patients with LVEF ≥ 58% and with 40% < LVEF < 58%.

CONCLUSION

A higher LVEF is independently related to poor prognosis in patients with HFpEF, in addition to concurrent AF and an elevated E/e' ratio. ACEI/ARB use, in contrast, was associated with improved prognosis, especially with regard to readmission due to HF.

CLINICAL TRIAL REGISTRATION

https://www.umin.ac.jp/ctr/index.htm.

UNIQUE IDENTIFIER

UMIN000017725.

Sex differences in heart failure patients assessed by combined echocardiographic and cardiopulmonary exercise testing

Background

We aimed to test the differences in peak VO₂ between males and females in patients diagnosed with heart failure (HF), using combined stress echocardiography (SE) and cardiopulmonary exercise testing (CPET).

Methods

Patients who underwent CPET and SE for evaluation of dyspnea or exertional intolerance at our institution, between January 2013 and December 2017, were included and retrospectively assessed. Patients were divided into three groups: HF with preserved ejection fraction (HFpEF), HF with mildly reduced or reduced ejection fraction (HFmrEF/HFrEF), and patients without HF (control). These groups were further stratified by sex.

Results

One hundred seventy-eight patients underwent CPET-SE testing, of which 40% were females. Females diagnosed with HFpEF showed attenuated increases in end diastolic volume index (P = 0.040 for sex × time interaction), significantly elevated E/e' (P < 0.001), significantly decreased left ventricle (LV) end diastolic volume:E/e ratio (P = 0.040 for sex × time interaction), and lesser increases in A-VO₂ difference (P = 0.003 for sex × time interaction), comparing to males with HFpEF. Females diagnosed with HFmrEF/HFrEF showed diminished increases in end diastolic volume index (P = 0.050 for sex × time interaction), mostly after anaerobic threshold was met, comparing to males with HFmrEF/HFrEF. This resulted in reduced increases in peak stroke volume index (P = 0.010 for sex × time interaction) and cardiac output (P = 0.050 for sex × time interaction).

Conclusions

Combined CPET-SE testing allows for individualized non-invasive evaluation of exercise physiology stratified by sex. Female patients with HF have lower exercise capacity compared to men with HF. For females diagnosed with HFpEF, this was due to poorer LV compliance and attenuated peripheral oxygen extraction, while for females diagnosed with HFmrEF/HFrEF, this was due to attenuated increase in peak stroke volume and cardiac output. As past studies have shown differences in clinical outcomes between females and males, this study provides an essential understanding of the differences in exercise physiology in HF patients, which may improve patient selection for targeted therapeutics.

Suppression of lusitropy as a disease mechanism in cardiomyopathies

In cardiac muscle the action of adrenaline on β1 receptors of heart muscle cells is essential to adjust cardiac output to the body's needs. Adrenergic activation leads to enhanced contractility (inotropy), faster heart rate (chronotropy) and faster relaxation (lusitropy), mainly through activation of protein kinase A (PKA). Efficient enhancement of heart output under stress requires all of these responses to work together. Lusitropy is essential for shortening the heartbeat when heart rate increases. It therefore follows that, if the lusitropic response is not present, heart function under stress will be compromised. Current literature suggests that lusitropy is primarily achieved due to PKA phosphorylation of troponin I (TnI) and phospholamban (PLB). It has been well documented that PKA-induced phosphorylation of TnI releases Ca2+ from troponin C faster and increases the rate of cardiac muscle relaxation, while phosphorylation of PLB increases SERCA activity, speeding up Ca2+ removal from the cytoplasm. In this review we consider the current scientific evidences for the connection between suppression of lusitropy and cardiac dysfunction in the context of mutations in phospholamban and thin filament proteins that are associated with cardiomyopathies. We will discuss what advances have been made into understanding the physiological mechanism of lusitropy due to TnI and PLB phosphorylation and its suppression by mutations and we will evaluate the evidence whether lack of lusitropy is sufficient to cause cardiomyopathy, and under what circumstances, and consider the range of pathologies associated with loss of lusitropy. Finally, we will discuss whether suppressed lusitropy due to mutations in thin filament proteins can be therapeutically restored.

Exercise-Induced Pulmonary Hypertension: A Valid Entity or Another Factor of Confusion?

Exercise-induced pulmonary hypertension EIPH has been defined as an increase in mean pulmonary arterial pressure (mPAP) during exercise in otherwise normal values at rest. EIPH reflects heart and/or lung dysfunction and may precede the development of manifest pulmonary hypertension (PH) in a proportion of patients. It is also associated with decreased life expectancy in patients with heart failure with reduced ejection fraction (HFrEF) or left ventricle (LV) valvular diseases. Diastolic dysfunction exacerbated during exercise relates to increased LV filling pressure and left atrial pressure (LAP). In this context backward, transmitted pressure alone or accompanied with backward blood flow promotes EIPH. The gold standard of EIPH assessment remains the right heart catheterization during exercise, which is an accurate but invasive method. Alternatively, non-invasive diagnostic modalities include exercise stress echocardiography (ESE) and cardiopulmonary exercise testing (CPET). Both diagnostic tests are performed under gradually increasing physical stress using treadmill and ergo-cycling protocols. Escalating workload during the exercise is analogous to the physiological response to real exercise. The results of the latter techniques show good correlation with invasive measurements, but they suffer from lack of validation and cut-off value determination. Although it is not officially recommended, there are accumulated data supporting the importance of EIPH diagnosis in the assessment of other mild/subclinical or probably fatal diseases in patients with latent PH or heart failure or LV valvular disease, respectively. Nevertheless, larger, prospective studies are required to ensure its role in clinical practice.

In Vivo Evaluation of a Novel Control Algorithm for Left Ventricular Assist Devices Based Upon Ventricular Stroke Work

The physical fitness of patients with terminal heart failure and an implanted left ventricular assist device (LVAD) might be improved by load-adaptive control of the LVAD. In this study, three control strategies for LVAD were compared in eight pigs: (1) a constant stroke work (CSW) control strategy that ensures a constant ventricular load using ventricular stroke work as the control variable; (2) a work ratio (WR) controller that maintains a constant ratio of ventricular work to hydraulic pump work; and (3) a controller that maintains the pump pace at a constant speed (CS). Biventricular heart insufficiency was induced by increased isoflurane application, and preload, afterload, and contractility alterations were performed. LVAD speed changes were significantly more pronounced in all load interventions with the CSW control strategy (preload: P < 0.001 vs. CS and P = 0.004 vs. WR; afterload: P < 0.001 vs. CS and P < 0.001 vs. WR; contractility: P < 0.001 vs. CS and P < 0.001 vs. WR). However, a significant difference in systemic flow only became evident in the experiments upon afterload increase ( P < 0.001 vs. CS and P = 0.004 vs. WR). An implementation of an evolved version of the CSW control strategy that dispenses with invasively measured parameters might be feasible for clinical use.

Relationship of arterial tonometry and exercise in patients with chronic heart failure: a systematic review with meta-analysis and trial sequential analysis

Background

Arterial stiffness is a common characteristic in patients with chronic heart failure (CHF), and arterial tonometric technologies related to arterial stiffness are novel and effective methods and have an important value in the diagnosis and prognosis of CHF. In terms of ameliorating arterial stiffness in patients with CHF, exercise training is considered an adjuvant treatment and also an effective means in the diagnosis and judgment of prognosis. However, there are huge controversies and inconsistencies in these aspects. The objective of this meta-analysis was to systematically test the connection of arterial tonometry and exercise in patients with CHF.

Methods

Databases, including MEDLINE, EMBASE, and Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library, were accessed from inception to 7 March 2022. The meta-analysis was then conducted, and trial sequential analysis (TSA) was performed jointly to further verify our tests and reach more convincing conclusions by using RevMan version 5.4 software, STATA version 16.0 software, and TSA version 0.9.5.10 Beta software.

Results

Eighteen articles were included, with a total of 876 participants satisfying the inclusion criteria. The pooling revealed that flow-mediated dilation (FMD) was lower in basal condition [standardized mean difference (SMD): − 2.28%, 95% confidence interval (CI) − 3.47 to − 1.08, P < 0.001] and improved significantly after exercise (SMD: 5.96%, 95% CI 2.81 to 9.05, P < 0.001) in patients with heart failure with reduced ejection fraction (HFrEF) compared with healthy participants. The high-intensity training exercise was more beneficial (SMD: 2.88%, 95% CI 1.78 to 3.97, P < 0.001) than the moderate-intensity training exercise to improve FMD in patients with CHF. For augmentation index (AIx), our study indicated no significant differences (SMD: 0.50%, 95% CI − 0.05 to 1.05, P = 0.074) in patients with heart failure with preserved ejection fraction (HFpEF) compared with healthy participants. However, other outcomes of our study were not identified after further verification using TSA, and more high-quality studies are needed to reach definitive conclusions in the future.

Conclusions

This review shows that FMD is lower in basal condition and improves significantly after exercise in patients with HFrEF compared with healthy population; high-intensity training exercise is more beneficial than moderate-intensity training exercise to improve FMD in patients with CHF; besides, there are no significant differences in AIx in patients with HFpEF compared with the healthy population. More high-quality studies on this topic are warranted.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12872-022-02792-6.

Left atrial dysfunction as the major driver of heart failure with preserved ejection fraction syndrome

Left atrial (LA) dysfunction seems to play a central role in the pathophysiology of heart failure with preserved ejection fraction (HFpEF), is associated with disease severity and poor outcomes and potentially impacts management. Identifying LA myopathy can help guide tailored therapy for HFpEF. Echocardiography allows the accurate measurement of atrial size and function, where LA strain appears to be a sensitive measure of intrinsic LA myopathy. Several therapies and devices that decompress of left atrium are being tested for HFpEF. Further investigation is required to understand the specific atrial effects of statins, mineralocorticoid receptor antagonists, and other therapies.

Characteristics of Heart Failure With Preserved Ejection Fraction Across the Range of Left Ventricular Ejection Fraction

BACKGROUND

Recent trial data suggest that stratification of patients with heart failure with preserved ejection fraction (HFpEF) according to left ventricular ejection fraction (LVEF) provides a means for dissecting different treatment responses. However, the differential pathophysiologic considerations have rarely been described.

METHODS

This prospective, single-center study analyzed consecutive symptomatic patients with HFpEF diagnosed according to the 2016 European Society of Cardiology heart failure guidelines. Patients were grouped into LVEF 50% to 60% and LVEF >60% cohorts. All patients underwent cardiac magnetic resonance imaging. Transfemoral cardiac catheterization was performed to derive load-dependent and load-independent left ventricular (LV) properties on pressure-volume loop analyses.

RESULTS

Fifty-six patients with HFpEF were enrolled and divided into LVEF 50% to 60% (n=21) and LVEF >60% (n=35) cohorts. On cardiac magnetic resonance imaging, the LVEF >60% cohort showed lower LV end-diastolic volumes (P=0.019) and end-systolic volumes (P=0.001) than the LVEF 50% to 60% cohort; stroke volume (P=0.821) did not differ between the cohorts. Extracellular volume fraction was higher in the LVEF 50% to 60% cohort than in the LVEF >60% cohort (0.332 versus 0.309; P=0.018). Pressure-volume loop analyses demonstrated higher baseline LV contractility (end-systolic elastance, 1.85 vs 1.33 mm Hg/mL; P<0.001) and passive diastolic stiffness (β constant, 0.032 versus 0.018; P=0.004) in the LVEF >60% cohort. Ventriculo-arterial coupling (end-systolic elastance/arterial elastance) at rest was in the range of optimized stroke work in the LVEF >60% cohort but was impaired in the LVEF 50% to 60% cohort (1.01 versus 0.80; P=0.005). During handgrip exercise, patients with LVEF >60% had higher increases in end-systolic elastance (1.85 versus 0.82 mm Hg/mL; P=0.023), attenuated increases in indexed end-systolic volume (-1 versus 7 mL/m²; P<0.004), and more exaggerated increases in LV filling pressures (8 vs 5 mm Hg; P=0.023). LV stroke volume decreased in the LVEF >60% cohort (P=0.007) under exertion.

CONCLUSIONS

Patients with HFpEF in whom LVEF ranged from 50% to 60% demonstrated reduced contractility, impaired ventriculo-arterial coupling, and higher extracellular volume fraction. In contrast, patients with HFpEF and a LVEF >60% demonstrated a hypercontractile state with excessive LV afterload and diminished preload reserve. A LVEF-based stratification of patients with HFpEF identified distinct morphologic and pathophysiologic subphenotypes.

Cardiopulmonary exercise responses in patients with non-ischemic heart failure and a mildly reduced ejection fraction

Background: The cardiopulmonary response to exercise in patients with heart failure exhibiting a mildly reduced ejection fraction (41% ≤ EF ≤ 49%) remains unclear. Materials & methods: A total of 193 consecutive patients with heart failure (excluding those with coronary artery disease) who underwent cardiopulmonary exercise (CPX) tests were examined. CPX variables were compared among patients with reduced, mildly reduced, and preserved EF. Results: The CPX test responses of patients with mildly reduced EF were similar to those of patients with reduced or preserved EF; however, increases in systolic blood pressure during exercise differed significantly (32 ± 26, 50 ± 24, and 41 ± 31 mmHg, respectively; p = 0.016). Grip strength and an increase in systolic blood pressure during exercise were independently associated with peak oxygen uptake in patients with mildly reduced EF (β = 0.41, 0.35, respectively; p < 0.05). Conclusion: Measurements of grip strength and blood pressure during exercise are useful predictors of prognoses in patients with non-ischemic and mildly reduced EF.

Exercise, Physical Activity, and Cardiometabolic Health: Insights into the Prevention and Treatment of Cardiometabolic Diseases

Physical activity (PA) and exercise are widely recognized as essential components of primary and secondary cardiovascular disease (CVD) prevention efforts and are emphasized in the health promotion guidelines of numerous professional societies and committees. The protean benefits of PA and exercise extend across the spectrum of CVD, and include the improvement and reduction of risk factors and events for atherosclerotic CVD (ASCVD), cardiometabolic disease, heart failure, and atrial fibrillation (AF), respectively. Here, we highlight recent insights into the salutary effects of PA and exercise on the primary and secondary prevention of ASCVD, including their beneficial effects on both traditional and nontraditional risk mediators; exercise "prescriptions" for ASCVD; the role of PA regular exercise in the prevention and treatment of heart failure; and the relationships between, PA, exercise, and AF. While our understanding of the relationship between exercise and CVD has evolved considerably, several key questions remain including the association between extreme volumes of exercise and subclinical ASCVD and its risk; high-intensity exercise and resistance (strength) training as complementary modalities to continuous aerobic exercise; and dose- and intensity-dependent associations between exercise and AF. Recent advances in molecular profiling technologies (ie, genomics, transcriptomics, proteomics, and metabolomics) have begun to shed light on interindividual variation in cardiometabolic responses to PA and exercise and may provide new opportunities for clinical prediction in addition to mechanistic insights.

Exercise Testing in HFpEF: an Appraisal Through Diagnosis, Pathophysiology and Therapy A Clinical Consensus Statement of the Heart Failure Association (HFA) and European Association of Preventive Cardiology (EAPC) of the European Society of Cardiology (ESC)

Patients with heart failure with preserved ejection fraction (HFpEF) universally complain of exercise intolerance and dyspnoea as key clinical correlates. Cardiac as well as extracardiac components play a role for the limited exercise capacity, including an impaired cardiac and peripheral vascular reserve, a limitation in mechanical ventilation and/or gas exchange with reduced pulmonary vascular reserve, skeletal muscle dysfunction and iron deficiency/anaemia. Although most of these components can be differentiated and quantified through gas exchange analysis by cardiopulmonary exercise testing (CPET), the information provided by objective measures of exercise performance have not been systematically considered in the recent algorithms/scores for HFpEF diagnosis, neither by European nor US groups. The current Clinical Consensus Statement by the HFA and EAPC Association of the ESC aims at outlining the role of exercise testing and its pathophysiological, clinical and prognostic insights, addressing the implication of a thorough functional evaluation from the diagnostic algorithm to the pathophysiology and treatment perspectives of HFpEF. Along with these goals, we provide a specific analysis on the evidence that CPET is the standard for assessing, quantifying, and differentiating the origin of dyspnoea and exercise impairment and even more so when combined with echo and/or invasive hemodynamic evaluation is here provided. This will lead to improved quality of diagnosis when applying the proposed scores and may also help useful to implement the progressive characterization of the specific HFpEF phenotypes, a critical step toward the delivery of phenotype-specific treatments.

GSK-3β Localizes to the Cardiac Z-Disc to Maintain Length Dependent Activation

BACKGROUND

Altered kinase localization is gaining appreciation as a mechanism of cardiovascular disease. Previous work suggests GSK-3β (glycogen synthase kinase 3β) localizes to and regulates contractile function of the myofilament. We aimed to discover GSK-3β's in vivo role in regulating myofilament function, the mechanisms involved, and the translational relevance.

METHODS

Inducible cardiomyocyte-specific GSK-3β knockout mice and left ventricular myocardium from nonfailing and failing human hearts were studied.

RESULTS

Skinned cardiomyocytes from knockout mice failed to exhibit calcium sensitization with stretch indicating a loss of length-dependent activation (LDA), the mechanism underlying the Frank-Starling Law. Titin acts as a length sensor for LDA, and knockout mice had decreased titin stiffness compared with control mice, explaining the lack of LDA. Knockout mice exhibited no changes in titin isoforms, titin phosphorylation, or other thin filament phosphorylation sites known to affect passive tension or LDA. Mass spectrometry identified several z-disc proteins as myofilament phospho-substrates of GSK-3β. Agreeing with the localization of its targets, GSK-3β that is phosphorylated at Y216 binds to the z-disc. We showed pY216 was necessary and sufficient for z-disc binding using adenoviruses for wild-type, Y216F, and Y216E GSK-3β in neonatal rat ventricular cardiomyocytes. One of GSK-3β's z-disc targets, abLIM-1 (actin-binding LIM protein 1), binds to the z-disc domains of titin that are important for maintaining passive tension. Genetic knockdown of abLIM-1 via siRNA in human engineered heart tissues resulted in enhancement of LDA, indicating abLIM-1 may act as a negative regulator that is modulated by GSK-3β. Last, GSK-3β myofilament localization was reduced in left ventricular myocardium from failing human hearts, which correlated with depressed LDA.

CONCLUSIONS

We identified a novel mechanism by which GSK-3β localizes to the myofilament to modulate LDA. Importantly, z-disc GSK-3β levels were reduced in patients with heart failure, indicating z-disc localized GSK-3β is a possible therapeutic target to restore the Frank-Starling mechanism in patients with heart failure.

[Invasive Cardiopulmonary Exercise Testing: A Review]

Right heart catheterization (RHC) is the internationally standardized reference method for measuring pulmonary hemodynamics under resting conditions. In recent years, increasing efforts have been made to establish the reliable assessment of exercise hemodynamics as well, in order to obtain additional diagnostic and prognostic data. Furthermore, cardiopulmonary exercise testing (CPET), as the most comprehensive non-invasive exercise test, is increasingly performed in combination with RHC providing detailed pathophysiological insights into the exercise response, so-called invasive cardiopulmonary exercise testing (iCPET).In this review, the accumulated experience with iCPET is presented and methodological details are discussed. This complex examination is especially helpful in differentiating the underlying causes of unexplained dyspnea. In particular, early forms of cardiac or pulmonary vascular dysfunction can be detected by integrated analysis of hemodynamic as well as ventilatory and gas exchange data. It is expected that with increasing validation of iCPET parameters, a more reliable differentiation of normal from pathological stress reactions will be possible.

Mitochondrial bioenergetics and D-ribose in HFpEF: a brief narrative review

Objective

In this review article, we briefly describe the status of treatment options for HFpEF and the role of mitochondrial dysfunction in the pathogenesis of HFpEF as an alternative therapeutic target. We also examine the mechanisms of D-ribose in cellular energy production and discuss the potential disadvantages and benefits of supplemental use of D-ribose in patients with HFpEF.

Background

Heart failure is a major cardiovascular disease that impacts over 6 million Americans and is one of the leading causes for morbidity and mortality. Patients with heart failure often experience shortness of breath and fatigue along with impaired physical capacity, all leading to poor quality of life. As a subtype of heart failure, heart failure with preserved ejection fraction (HFpEF) is characterized with impaired diastolic function. Currently, there are no effective treatments specifically for HFpEF, thus clinicians and researchers are searching for therapies to improve cardiac function. Emerging evidence indicate that mitochondrial dysfunction and impaired cardiac bioenergetics are among the underlying mechanisms for HFpEF. There is increased interest in investigating the use of supplements such as D-ribose to enhance mitochondrial function and improve production of adenosine triphosphate (ATP).

Methods

For this narrative review, more than 100 relevant scientific articles were considered from various databases (e.g., PubMed, Web of Science, CINAHL, and Google Scholar) using the keywords “Heart Failure”, “HFpEF”, “D-ribose”, “ATP”, “Mitochondria”, Bioenergetics”, and “Cellular Respiration”.

Conclusions

It is essential to find potential targeted therapeutic treatments for HFpEF. Since there is evidence that the HFpEF is related to impaired myocardial bioenergetics, enhancing mitochondrial function could augment cardiac function. Using a supplement such as D-ribose could improve mitochondrial function by increasing ATP and enhancing cardiac performance for patients with HFpEF. There is a recently completed clinical trial with HFpEF patients that indicates D-ribose increases ATP production and improves cardiac ejection fraction.

Relation of left atrial function with exercise capacity and muscle endurance in patients with heart failure

Aims

Both left atrial strain (LAS) and skeletal muscle endurance demonstrate a linear relationship to peak VO₂. Less is known about the relationship between central (cardiac) and peripheral (muscle endurance) limitations of exercise capacity in patients with heart failure (HF). We investigated this relationship using novel cardiac markers such as LAS and left atrial emptying fraction (LAEF).

Methods and results

We analysed echocardiographic measurements, cardiopulmonary exercise testing (CPET), and isokinetic muscle function in 55 subjects with HF and controls [17 heart failure with preserved ejection fraction (HFpEF), 18 heart failure with reduced ejection fraction (HFrEF), and 20 healthy controls]. Patients with reduced LAEF showed reduced peak VO₂: 14.3 ± 3.5 vs. 18.5 ± 3.5 mL/min/kg, P = 0.003, and reduced muscle endurance (RME): 64.3 ± 23.9 vs. 88.5 ± 32.3 Nm/kg, P = 0.028. Patients with reduced LAS showed similar results. Neither left ventricular global longitudinal strain (LVGLS) nor left atrial volume index (LAVI) was associated with RME. The area under the curve of LAS and LAEF in patients with HF in association with RME were (0.76 vs. 0.80) with 95% confidence interval (CI) (0.59–0.96, P = 0.012 vs. 0.63–0.98, P = 0.006, respectively). In a multiple linear regression, LAEF and working load measured during CPET (watt) were independent factors for RME after adjusting for age, LVGLS, and 6 min walk test (6MWT) [LAEF (B: 0.09, 95% CI: 1.01; 1.18, P = 0.024), working load (B: 0.05, 95% CI: 1.01; 1.08, P = 0.006)]. Peak torque of the left leg was associated with E/LAS (E: early diastolic) in patients with HFpEF (r = −0.6, P = 0.020). Endurance of the left leg was associated with LAEF (r = 0.79, P = 0.001) in patients with HFrEF.

Conclusions

LAS/LAEF are potential cardiac markers in demonstrating the link between cardiac and peripheral limitations of exercise capacity. Thus, integrating LAS/LAEF in the evaluation of exercise intolerance in patients with HF could be useful.

Cardiac rehabilitation in heart failure: Indications for exercise training based on heart failure phenotype

Exercise intolerance with dyspnea and fatigue is pervasive amongst individuals with heart failure (HF) due to both central and peripheral mechanisms. Cardiac rehabilitation (CR) is a cornerstone therapy for numerous cardiovascular disease (CVD) processes, and it's use in HF with reduced ejection fraction (HFrEF) has shown significant benefit in improved mortality and quality of life (QoL). Less is known about the benefit of CR in the setting of HF with preserved ejection fraction (HFpEF), and optimal exercise therapy (ET) may vary based on underlying disease phenotype. Here we offer review of existing data for ET in both HFrEF and HFpEF with proposed exercise treatment modalities based on underlying comorbidities and variable phenotypes.

Comprehensive Physiological Modeling Provides Novel Insights Into Heart Failure With Preserved Ejection Fraction Physiology

Background

Although a rapid rise in left atrial pressure during exertion is considered pathognomonic of heart failure with preserved ejection fraction (HFpEF), the fundamental circulatory determinants of this response are not clear, impacting upon the development of more effective therapies. We aimed to comprehensively describe the circulatory mechanics of patients with HFpEF at rest and during exercise in comparison with controls.

Methods and Results

We performed simultaneous right‐heart catheterization and echocardiography at rest and during exercise in 22 healthy control volunteers and 60 patients with confirmed HFpEF. Using detailed individual patient‐level hemodynamic and left ventricular ejection fraction data we performed computer simulations to evaluate the circulatory parameters including the estimated stressed blood volumethat contribute to the resting and exercise pulmonary capillary pressure. At rest and during exercise, left ventricular stiffness (V₃₀, the end‐diastolic pressure–volume relationship at a filling pressure of 30 mm Hg), left ventricular elastance, and arterial elastance were all significantly greater in HFpEF than in controls. Stressed blood volume was significantly greater in HFpEF (26.9±5.4 versus 20.2±4.7 mL/kg, P<0.001), becoming even more pronounced during exercise (40.9±3.7 versus 27.5±7.0 mL per 70 kg, P<0.001). During exercise, the magnitude of the change in stressed blood volume (r=0.67, P<0.001) and left ventricular stiffness (r=−0.44, P<0.001) were key determinants of the rise in pulmonary capillary wedge pressure. Further detailed modeling studies showed that the hemodynamic response to exercise results from a complex non‐linear interaction between circulatory parameters.

Conclusions

The circulatory determinants of HFpEF physiology are complex. We identified stressed blood volume at rest and during exercise is a novel, key factor, therebyrepresenting an important potential therapeutic target.

Similarities and Differences Between HFmrEF and HFpEF

The new guidelines classify heart failure (HF) into three subgroups based on the ejection fraction (EF): HF with reduced EF (HFrEF), HF with mid-range EF (HFmrEF), and HF with preserved EF (HFpEF). The new guidelines regarding the declaration of HFmrEF as a unique phenotype have achieved the goal of stimulating research on the basic characteristics, pathophysiology, and treatment of HF patients with a left ventricular EF of 40-49%. Patients with HFmrEF have more often been described as an intermediate population between HFrEF and HFpEF patients; however, with regard to etiology and clinical indicators, they are more similar to the HFrEF population. Concerning clinical prognosis, they are closer to HFpEF because both populations have a good prognosis and quality of life. Meanwhile, growing evidence indicates that HFmrEF and HFpEF show heterogeneity in presentation and pathophysiology, and the emergence of this heterogeneity often plays a crucial role in the prognosis and treatment of the disease. To date, the exact mechanisms and effective treatment strategies of HFmrEF and HFpEF are still poorly understood, but some of the current evidence, from observational studies and post-hoc analyses of randomized controlled trials, have shown that patients with HFmrEF may benefit more from HFrEF treatment strategies, such as beta-blockers, angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, mineralocorticoid receptor antagonists, and sacubitril/valsartan. This review summarizes available data from current clinical practice and mechanistic studies in terms of epidemiology, etiology, clinical indicators, mechanisms, and treatments to discuss the potential association between HFmrEF and HFpEF patients.

The regulatory light chain mediates inactivation of myosin motors during active shortening of cardiac muscle

The normal function of heart muscle depends on its ability to contract more strongly at longer length. Increased venous filling stretches relaxed heart muscle cells, triggering a stronger contraction in the next beat- the Frank-Starling relation. Conversely, heart muscle cells are inactivated when they shorten during ejection, accelerating relaxation to facilitate refilling before the next beat. Although both effects are essential for the efficient function of the heart, the underlying mechanisms were unknown. Using bifunctional fluorescent probes on the regulatory light chain of the myosin motor we show that its N-terminal domain may be captured in the folded OFF state of the myosin dimer at the end of the working-stroke of the actin-attached motor, whilst its C-terminal domain joins the OFF state only after motor detachment from actin. We propose that sequential folding of myosin motors onto the filament backbone may be responsible for shortening-induced de-activation in the heart.

Combined use of stress echocardiography and cardiopulmonary exercise testing to assess exercise intolerance in patients treated for acute myocardial infarction

Exercise intolerance after acute myocardial infarction (AMI) is a predictor of worse prognosis, but its causes are complex and poorly studied. This study assessed the determinants of exercise intolerance using combined stress echocardiography and cardiopulmonary exercise testing (CPET-SE) in patients treated for AMI. We prospectively enrolled patients with left ventricular ejection fraction (LV EF) ≥40% for more than 4 weeks after the first AMI. Stroke volume, heart rate, and arteriovenous oxygen difference (A-VO2Diff) were assessed during symptom-limited CPET-SE. Patients were divided into four groups according to the percentage of predicted oxygen uptake (VO2) (Group 1, <50%; Group 2, 50-74%; Group 3, 75-99%; and Group 4, ≥100%). Among 81 patients (70% male, mean age 58 ± 11 years, 47% ST-segment elevation AMI) mean peak VO2 was 19.5 ± 5.4 mL/kg/min. A better exercise capacity was related to a higher percent predicted heart rate (Group 2 vs. Group 4, p <0.01), higher peak A-VO2Diff (Group 1 vs. Group 3, p <0.01) but without differences in stroke volume. Peak VO2 and percent predicted VO2 had a significant positive correlation with percent predicted heart rate at peak exercise (r = 0.28, p = 0.01 and r = 0.46, p < 0.001) and peak A-VO2Diff (r = 0.68, p <0.001 and r = 0.36, p = 0.001) but not with peak stroke volume. Exercise capacity in patients treated for AMI with LV EF ≥40% is related to heart rate response during exercise and peak peripheral oxygen extraction. CPET-SE enables non-invasive assessment of the mechanisms of exercise intolerance.

Impact of admission hyperglycaemia on clinical outcomes in non-diabetic heart failure with preserved ejection fraction

Aims

At present, the clinical significance of admission hyperglycaemia in heart failure with preserved ejection fraction (HFpEF) patients remains unknown. This study was designed to evaluate the relationship between admission hyperglycaemia and clinical outcome in HFpEF patients, especially in non‐diabetic patients.

Methods and results

We enrolled 486 non‐diabetic HFpEF (left ventricular ejection fraction ≥50%) patients hospitalized due to acute decompensated heart failure from the PURSUIT‐HFpEF registry, a prospective, multicentre observational study. We divided non‐diabetic patients into two groups, an admission hyperglycaemia group whose blood glucose on admission was ≥7.0 mmol/L (148 patients) and a normoglycaemic group whose blood glucose on admission was <7.0 mmol/L (338 patients). The primary endpoint was all‐cause mortality, and the secondary endpoints were heart failure death and other causes of cardiac death. During a mean follow‐up period of 400 ± 335 days, all‐cause mortality was 69 patients. Twenty‐five patients suffered cardiac death. All‐cause mortality (P = 0.002), cardiac death (P = 0.009), and heart failure death (P = 0.001) were significantly more frequent in the admission hyperglycaemia group than in the normoglycaemic group. Admission hyperglycaemia was independently and significantly associated with all‐cause mortality and cardiac death (HR 2.01, 95% CI 1.20–3.34, P = 0.008 and HR 3.03, 95% CI 1.35–6.96, P = 0.007, respectively).

Conclusions

Non‐diabetic HFpEF patients with admission hyperglycaemia when hospitalized for heart failure had poorer clinical outcomes than normoglycaemic patients.

Incremental value of diastolic stress test in identifying subclinical heart failure in patients with diabetes mellitus

AIMS

Resting echocardiography is a valuable method for detecting subclinical heart failure (HF) in patients with diabetes mellitus (DM). However, few studies have assessed the incremental value of diastolic stress for detecting subclinical HF in this population.

METHODS AND RESULTS

Asymptomatic patients with Type 2 DM were prospectively enrolled. Subclinical HF was assessed using systolic dysfunction (left ventricular longitudinal strain <16% at rest and <19% after exercise in absolute value), abnormal cardiac morphology, or diastolic dysfunction (E/e' > 10). Metabolic equivalents (METs) were calculated using treadmill speed and grade, and functional capacity was assessed by percent-predicted METs (ppMETs). Among 161 patients studied (mean age of 59 ± 11 years and 57% male sex), subclinical HF was observed in 68% at rest and in 79% with exercise. Among characteristics, diastolic stress had the highest yield in improving detection of HF with 57% of abnormal cases after exercise and 45% at rest. Patients with revealed diastolic dysfunction during stress had significantly lower exercise capacity than patients with normal diastolic stress (7.3 ± 2.1 vs. 8.8 ± 2.5, P < 0.001 for peak METs and 91 ± 30% vs. 105 ± 30%, P = 0.04 for ppMETs). On multivariable modelling found that age (beta = -0.33), male sex (beta = 0.21), body mass index (beta = -0.49), and exercise E/e' >10 (beta = -0.17) were independently associated with peak METs (combined R2 = 0.46). A network correlation map revealed the connectivity of peak METs and diastolic properties as central features in patients with DM.

CONCLUSION

Diastolic stress test improves the detection of subclinical HF in patients with diabetes mellitus.

Peripheral Oxygen Extraction and Exercise Limitation in Asymptomatic Patients with Diabetes Mellitus

Patients with diabetes mellitus (DM) frequently present reduced exercise capacity. We aimed to explore the extent to which peripheral extraction relates to exercise capacity in asymptomatic patients with DM. We prospectively enrolled 98 asymptomatic patients with type-2 DM (mean age of 59 ± 11 years and 56% male sex), and compared with 31 age, sex and body mass index-matched normoglycemic controls. Cardiopulmonary exercise testing with resting followed by stress echocardiography was performed. Exercise response was assessed using peak oxygen uptake (peak VO₂) and ventilatory efficiency was measured using the slope of the relationship between minute ventilation and carbon dioxide production (VE/VCO₂). Peripheral extraction was calculated as the ratio of VO₂ to cardiac output. Cardiac function was evaluated using left ventricular longitudinal strain, E/e', and relative wall thickness. Among patients with DM, 26 patients (27%) presented reduced percent-predicted-peak VO₂(<80%) and 18 (18%) presented abnormal VE/VCO₂slope (>34). There was no significant difference in peak cardiac output; however, peripheral extraction was lower in patients with DM compared to controls. Higher peak E/e' (beta = -0.24, p = 0.004) was associated with lower peak VO₂ along with age, sex and body mass index (R² = 0.53). A cluster analysis found left ventricular longitudinal strain, E/e', relative wall thickness and peak VO₂ in different clusters. In conclusion, impaired peripheral extraction may contribute to reduced peak VO₂in asymptomatic patients with DM. Furthermore, a cluster analysis suggests that cardiopulmonary exercise testing and echocardiography may be complementary for defining subclinical heart failure in patients with DM.

Stress Testing in Heart Failure with Preserved Ejection Fraction

Exertional dyspnea is the most common symptom in patients with heart failure with preserved ejection fraction; however, it is not specific to this disease. Stress testing provides crucial information about the diagnosis and prognosis of heart failure with preserved ejection before it reaches the advanced stage. Among various stress tests, noninvasive supine bicycle diastolic stress echocardiography has provided the most evidence for diagnosing and predicting the prognosis of heart failure with preserved ejection fraction. In current practice guidelines, a noninvasive or invasive diastolic stress test is recommended when a diagnosis is unclear in resting echocardiography.

Current clinical applications of spectral tissue Doppler echocardiography (E/e' ratio) as a noninvasive surrogate for left ventricular diastolic pressures in the diagnosis of heart failure with preserved ejection fraction. Revisited 15 years later

It is currently well established that more than half of heart failure patients have preserved ejection fraction. The diagnosis of heart failure with preserved ejection fraction is complex in clinical practice despite ESC recommendations issued in 2019. In this context, the demonstration of increased left ventricular filling pressures at rest or during exercise allows a definite diagnosis of heart failure with preserved ejection fraction in patients with signs and/or symptoms compatible with the diagnosis and a preserved ejection fraction. The spectral tissue Doppler-derived E/e' ratio by transthoracic Doppler echocardiography has been validated in the noninvasive assessment of left ventricular diastolic pressures at rest and during exercise. Several studies report the validity of E/e' in the diagnosis of heart failure with preserved ejection fraction in patients with both isolated exertional and acute dyspnea, as well as in risk stratification. In light of the current literature, E/e' deserves to be included on every transthoracic Doppler echocardiography report in patients with suspected heart failure with preserved ejection fraction. This updated review provides an overview of the diagnostic relevance of E/e' in patients in its two modes of clinical presentation, isolated exertional dyspnea and the decompensated congestive form.

Pathophysiology of Exercise Intolerance and Its Treatment With Exercise-Based Cardiac Rehabilitation in Heart Failure With Preserved Ejection Fraction

Heart failure with preserved ejection fraction (HFpEF) is the fastest growing form of heart failure in the United States. The cardinal feature of HFpEF is reduced exercise tolerance (peak oxygen uptake, (Equation is included in full-text article.)O2peak) secondary to impaired cardiac, vascular, and skeletal muscle function. There are currently no evidence-based drug therapies to improve clinical outcomes in patients with HFpEF. In contrast, exercise training is a proven effective intervention for improving (Equation is included in full-text article.)O2peak, aerobic endurance, and quality of life in HFpEF patients. This brief review discusses the pathophysiology of exercise intolerance and the role of exercise training to improve (Equation is included in full-text article.)O2peak in clinically stable HFpEF patients. It also discusses the mechanisms responsible for the exercise training-mediated improvements in (Equation is included in full-text article.)O2peak in HFpEF. Finally, it provides evidence-based exercise prescription guidelines for cardiac rehabilitation specialists to assist them with safely implementing exercise-based cardiac rehabilitation programs for HFpEF patients.

"Accelerated aging" of the heart as heart failure with preserved ejection fraction-analysis using leg-positive pressure stress echocardiography

The aging process is a significant risk factor for heart failure. The incidence of heart failure with preserved ejection fraction (HFpEF) dramatically increases with age. Although HFpEF occurs along a continuum of aging of the cardiovascular system, the pathophysiology that differentiates overt HFpEF from physiological aging is not fully understood. A total of 102 subjects were prospectively recruited: 25 patients with HFpEF and 77 healthy controls. Controls were stratified into three age-groups: young (n = 27, 20-40 years), middle aged (n = 25, 40-65 years), and elderly (n = 25, > 65 years). All participants underwent preload stress echocardiography using a leg-positive pressure (LPP) maneuver. With an increase in age, progressive concentric left ventricular (LV) remodeling was observed in healthy controls, resulting in the hemodynamic consequences of an age-dependent increase in the E/e' ratio (ANOVA, P < 0.001). During LPP stress, the E/e' ratio significantly increased in the middle-aged and elderly groups (from 8 ± 2 to 9 ± 3, from 10 ± 2 to 12 ± 3, P < 0.05, respectively), and this was more pronounced in patients with HFpEF (from 16 ± 5 to 17 ± 7, P < 0.05). Forward stroke volume (SV) significantly increased in each healthy group during LPP stress (all P < 0.001) but failed to increase in the HFpEF group (from 43 ± 13 to 44 ± 14 mL/m², P = 0.65). In a multivariate analysis, LV mass index (odds ratio [OR] 1.051, P < 0.05), E/e' ratio (OR 1.480; P < 0.05), and change in SV (OR 0.780; P < 0.05) were independent parameters that differentiated HFpEF from physiological aging. Structural remodeling and impaired preload reserve may both be critical features that characterize the pathophysiology of HFpEF.

Determinants and consequences of heart rate and stroke volume response to exercise in patients with heart failure and preserved ejection fraction

AIMS

A hallmark of heart failure with preserved ejection fraction (HFpEF) is impaired exercise capacity of varying severity. The main determinant of exercise capacity is cardiac output (CO), however little information is available about the relation between the constituents of CO - heart rate and stroke volume - and exercise capacity in HFpEF. We sought to determine if a heterogeneity in heart rate and stroke volume response to exercise exists in patients with HFpEF and describe possible clinical phenotypes associated with differences in these responses.

METHODS AND RESULTS

Data from two prospective trials of HFpEF (n = 108) and a study of healthy participants (n = 42) with invasive haemodynamic measurements during exercise were utilized. Differences in central haemodynamic responses were analysed with regression models. Chronotropic incompetence was present in 39-56% of patients with HFpEF and 3-56% of healthy participants depending on the definition used, but some (n = 47, 44%) had an increase in heart rate similar to that of healthy controls. Patients with HFpEF had a smaller increase in their stroke volume index (SVI) (HFpEF: +4 ± 10 mL/m² , healthy participants: +24 ± 12 mL/m² , P < 0.0001), indeed, SVI fell in 28% of patients at peak exercise. Higher body mass index and lower SVI at rest were associated with smaller increases in heart rate during exercise, whereas higher resting heart rate, and angiotensin-converting enzyme inhibitor/angiotensin II receptor blocker use were associated with a greater increase in SVI in patients with HFpEF.

CONCLUSION

The haemodynamic response to exercise was very heterogeneous among patients with HFpEF, with chronotropic incompetence observed in up to 56%, and 28% had impaired increase in SVI. This suggests that haemodynamic exercise testing may be useful to identify which HFpEF patients may benefit from interventions targeting stroke volume and chronotropic response.

Role of Ischemic Heart Disease in Major Adverse Renal and Cardiac Events Among Individuals With Heart Failure With Preserved Ejection Fraction (from the TOPCAT Trial)

Despite improvements in the prognosis of patients with heart failure with reduced ejection fraction (HFrEF), established therapy for heart failure patients with preserved ejection fraction (HFpEF) is lacking. Additionally, ischemic heart disease adversely impacts the clinical course of HFrEF patients; however, its role in HFpEF is not fully understood. We conducted a post hoc analysis of propensity score matched patients from the Treatment of Preserved Cardiac Function Heart Failure with an Aldosterone Antagonist trial to compare HFpEF patients with versus without myocardial ischemia in terms of major adverse renal and/or cardiac events (MARCE). Of 3,445 participants, the prevalence of ischemia was 59%. For this analysis, we included 1,747 ischemic patients and 1,207 propensity matched nonischemic patients. Ischemia was associated with a 20% increased risk (HR = 1.20, 95% confidence interval [CI] = 1.042 to 1.382, p value = 0.0112) of major adverse renal and/or cardiac events (MARCE) in adjusted analyses. Other important predictors of MARCE were diabetes (hazard ratio [HR] = 1.60, 95% CI = 1.38 to 1.87, p <0.0001), dyslipidemia (HR = 1.30, 95% CI = 1.10 to 1.52, p = 0.001) and smoking (HR = 1.33, 95% CI = 1.04 to 1.69, p = 0.0197). Revascularization was not significantly associated with MARCE in the subgroup of ischemic HFpEF patients. Future work is warranted to develop tailored interventions for patients with both HFpEF and ischemic heart disease to mitigate the risk of MARCE .

[The role of diastolic transthoracic stress echocardiography with incremental workload in the evaluation of heart failure with preserved ejection fraction: indications, methodology, interpretation. Expert consensus developed under the auspices of the National Medical Research Center of Cardiology, Society of Experts in Heart Failure (SEHF), and Russian Association of Experts in Ultrasound Diagnosis in Medicine (REUDM)]

Diagnosis of heart failure with preserved ejection fraction (HFpEF) is associated with certain difficulties since many patients with HFpEF have a slight left ventricular diastolic dysfunction and normal filling pressure at rest. Diagnosis of HFpEF is improved by using diastolic transthoracic stress-echocardiography with dosed exercise (or diastolic stress test), which allows detection of increased filling pressure during the exercise. The present expert consensus explains the requirement for using the diastolic stress test in diagnosing HFpEF from clinical and pathophysiological standpoints; defines indications for the test with a description of its methodological aspects; and addresses issues of using the test in special patient groups.

How to diagnose heart failure with preserved ejection fraction: the HFA-PEFF diagnostic algorithm: a consensus recommendation from the Heart Failure Association (HFA) of the European Society of Cardiology (ESC)

Making a firm diagnosis of chronic heart failure with preserved ejection fraction (HFpEF) remains a challenge. We recommend a new stepwise diagnostic process, the 'HFA-PEFF diagnostic algorithm'. Step 1 (P=Pre-test assessment) is typically performed in the ambulatory setting and includes assessment for HF symptoms and signs, typical clinical demographics (obesity, hypertension, diabetes mellitus, elderly, atrial fibrillation), and diagnostic laboratory tests, electrocardiogram, and echocardiography. In the absence of overt non-cardiac causes of breathlessness, HFpEF can be suspected if there is a normal left ventricular ejection fraction, no significant heart valve disease or cardiac ischaemia, and at least one typical risk factor. Elevated natriuretic peptides support, but normal levels do not exclude a diagnosis of HFpEF. The second step (E: Echocardiography and Natriuretic Peptide Score) requires comprehensive echocardiography and is typically performed by a cardiologist. Measures include mitral annular early diastolic velocity (e'), left ventricular (LV) filling pressure estimated using E/e', left atrial volume index, LV mass index, LV relative wall thickness, tricuspid regurgitation velocity, LV global longitudinal systolic strain, and serum natriuretic peptide levels. Major (2 points) and Minor (1 point) criteria were defined from these measures. A score ≥5 points implies definite HFpEF; ≤1 point makes HFpEF unlikely. An intermediate score (2-4 points) implies diagnostic uncertainty, in which case Step 3 (F1: Functional testing) is recommended with echocardiographic or invasive haemodynamic exercise stress tests. Step 4 (F2: Final aetiology) is recommended to establish a possible specific cause of HFpEF or alternative explanations. Further research is needed for a better classification of HFpEF.

Combined Echocardiographic and Cardiopulmonary Exercise to Assess Determinants of Exercise Limitation in Chronic Obstructive Pulmonary Disease

BACKGROUND

Current methods do not allow a thorough assessment of causes associated with limited exercise capacity in patients with chronic obstructive pulmonary disease (COPD).

METHODS

Twenty patients with COPD and 20 matched control subjects were assessed using combined cardiopulmonary and stress echocardiographic testing. Various echocardiographic parameters (left ventricular [LV] volumes, right ventricular [RV] area, ejection fraction, stroke volume, S', and E/e' ratio) and ventilatory parameters (peak oxygen consumption [Vo₂] and A-Vo₂ difference) were measured to evaluate LV and RV function, hemodynamics, and peripheral oxygen extraction (A-VO₂ difference).

RESULTS

Significant differences (both between groups and for group-by-time interaction) were seen in exercise responses (LV volume, RV area, LV volume/RV area ratio, S', E/e' ratio, tricuspid regurgitation grade, heart rate, stroke volume, and Vo₂). The major mechanisms of reduced exercise tolerance in patients with COPD were bowing of the septum to the left in 12 (60%), abnormal increases in E/e' ratio in 12 (60%), abnormal stroke volume reserve in 16 (80%), low peak A-Vo₂ difference in 10 (50%), chronotropic incompetence in 13 (65%), or a combination of several mechanisms. Patients with COPD and poor exercise tolerance showed attenuated increases in stroke volume, heart rate, and A-Vo₂ difference and exaggerated changes in LV/RV ratio and LV compliance (ratio of LV volume to E/e' ratio) compared with patients with COPD with good exercise tolerance.

CONCLUSIONS

Combined cardiopulmonary and stress echocardiographic testing can be helpful in determining individual mechanisms of exercise intolerance in patients with COPD. In patients with COPD, exercise intolerance is predominantly the result of chronotropic incompetence, limited stroke volume reserve, exercise-induced elevation in left filling pressure, and peripheral factors and not simply obstructive lung function. Limited stroke volume is related to abnormal RV contractile reserve and reduced LV compliance introduced through septal flattening and direct ventricular interaction.

Heart failure with preserved ejection fraction diminishes peripheral hemodynamics and accelerates exercise-induced neuromuscular fatigue

This study investigated the impact of HFpEF on neuromuscular fatigue and peripheral hemodynamics during small muscle mass exercise not limited by cardiac output. Eight HFpEF patients (NYHA II-III, ejection-fraction: 61 ± 2%) and eight healthy controls performed dynamic knee extension exercise (80% peak workload) to task failure and maximal intermittent quadriceps contractions (8 × 15 s). Controls repeated knee extension at the same absolute intensity as HFpEF. Leg blood flow (Q_L) was quantified using Doppler ultrasound. Pre/postexercise changes in quadriceps twitch torque (ΔQ_tw; peripheral fatigue), voluntary activation (ΔVA; central fatigue), and corticospinal excitability were quantified. At the same relative intensity, HFpEF (24 ± 5 W) and controls (42 ± 6 W) had a similar time-to-task failure (∼10 min), ΔQ_tw (∼50%), and ΔVA (∼6%). This resulted in a greater exercise-induced change in neuromuscular function per unit work in HFpEF, which was significantly correlated with a slower Q_L response time. Knee extension exercise at the same absolute intensity resulted in an ∼40% lower Q_L and greater ΔQ_tw and ΔVA in HFpEF than in controls. Corticospinal excitability remained unaltered during exercise in both groups. Finally, despite a similar ΔVA, ΔQ_tw was larger in HFpEF versus controls during isometric exercise. In conclusion, HFpEF patients are characterized by a similar development of central and peripheral fatigue as healthy controls when tested at the same relative intensity during exercise not limited by cardiac output. However, HFpEF patients have a greater susceptibility to neuromuscular fatigue during exercise at a given absolute intensity, and this impairs functional capacity. The patients' compromised Q_L response to exercise likely accounts, at least partly, for the patients' attenuated fatigue resistance.NEW & NOTEWORTHY The susceptibility to neuromuscular fatigue during exercise is substantially exaggerated in individuals with heart failure with a preserved ejection fraction. The faster rate of fatigue development is associated with the compromised peripheral hemodynamic response characterizing these patients during exercise. Given the role of neuromuscular fatigue as a factor limiting exercise, this impairment likely accounts for a significant portion of the exercise intolerance typical for this population.