Exercise-induced mitral regurgitation and right ventricle to pulmonary circulation uncoupling across the heart failure phenotypes

Impact of Exercise on Atrial Functional Mitral Regurgitation and Its Determinants: An Exercise Echocardiographic Study

Atrial functional mitral regurgitation (AFMR) is a distinct form of mitral regurgitation in patients with atrial fibrillation and heart failure with preserved ejection fraction. Its pathophysiology remains elusive, and data on exercise-related AFMR are scarce. We sought to investigate the impact of acute exercise on AFMR severity and to identify its determinants. In total, 47 patients with heart failure with preserved ejection fraction (n = 39) and/or atrial fibrillation (n = 22) were enrolled. We assessed AFMR severity, mitral annular dimensions, left atrial size, AFMR severity, and parameters of systolic and diastolic function at rest and during maximal exercise by echocardiography. An increase in AFMR severity of ≥1 grade was observed in 20 patients (43%) during exercise and was associated with impaired progression of peak mitral annulus systolic velocity and increased systolic mitral annular diameter during exercise, whereas the systolic annular diameter decreased in patients without AFMR progression. Furthermore, patients with ≥ moderate AFMR during exercise (n = 19, 40%) had lower peak mitral annulus systolic velocity, greater systolic mitral annular diameters, reduced tricuspid annular plane systolic excursion, and more severe tricuspid regurgitation than patients with ≤ mild MR during exercise. In conclusion, AFMR is a dynamic condition which may worsen during exercise. Deterioration of AFMR during exercise was associated with impaired longitudinal left ventricular contractile reserve and greater mitral annular dimensions. Because impaired left ventricular longitudinal function may influence mitral annular dynamics, this attributes to the hypothesis that AFMR results from mitral annulus area/leaflet area imbalance caused by annular dilation and impaired mitral annular dynamics.

Right ventricular reserve in cardiopulmonary disease: A simultaneous hemodynamic and three-dimensional echocardiographic study

BACKGROUND

Right ventricular (RV) reserve has been linked to exercise capacity and prognosis in cardiopulmonary diseases. However, evidence in this setting is limited, due to the complex shape and load dependency of the RV. We sought to study RV adaptation to exercise by simultaneous three-dimensional echocardiography (3DE) and right heart catheterization (RHC).

METHODS

Patients with heart failure with preserved ejection fraction (HFpEF) or pulmonary vascular disease (PVD) underwent simultaneous supine rest/exercise RHC-3DE. They were subdivided based on RV ejection fraction (EF) changes: (1) exhausted RV reserve, RVEF-; (2) preserved RV reserve, RVEF+.

RESULTS

Sixty percent of patients were RVEF-. Distribution of HFpEF/PVD, as well as RV volumes and RVEF at rest were similar in the 2 groups. Hemodynamic metrics of RV afterload, as well as their exercise-induced changes, were similar in the 2 groups. During exercise, RV end-diastolic volume increased more in RVEF- than in RVEF+ (29±29 vs 7±25 ml, p<0.05). RV end-systolic volume increased by 21[12;31] ml in RVEF- and decreased by 8[-15;1] ml in RVEF+ (p<0.001). RV-pulmonary artery coupling was lower in RVEF- at peak exercise (p<0.05). Peak RVEF was associated with left ventricular preload (R2=0.14, p=0.011). Cardiac output increased less in RVEF- than in RVEF+ (+2.3±2.0 vs +4.0±2.4 liter/min, p<0.05). Peak RVEF was associated with oxygen consumption (p<0.01).

CONCLUSIONS

Exhausted RV reserve, as evaluated by 3DE, was frequent in HFpEF and PVD, was relatively independent from classical afterload parameters, was associated with RV-pulmonary artery decoupling, RV dilation, enhanced ventricular interdependence, and cardiac limitation to exercise. Intrinsic RV dysfunction may contribute to exhausted RV reserve.

Functional Mitral Regurgitation and Heart Failure With Preserved Ejection Fraction: Clinical Implications and Management

Heart failure with preserved ejection fraction (HFpEF) is highly prevalent and associated with worse cardiovascular outcomes. The pathophysiology of HFpEF mostly relies on the development of elevated left ventricle filling pressure, diastolic dysfunction, and atrial dilatation and impairment. This dynamic process may eventually lead to the development of functional mitral regurgitation (MR), characterized by mitral annular dilatation and consequent leaflet remodeling, in the context of preserved left ventricular ejection fraction. These observations highlight the possible common pathophysiology of MR and HFpEF. However, less is known about the prevalence and the clinical value of MR in the context of HFpEF. This review aims to provide an overview of the association and interplay between functional MR and HFpEF, discuss the underlying mechanisms that are common to these diseases, and summarize potential targeted pharmacological treatments.

Different heart failure phenotypes of valvular heart disease: the role of mitochondrial dysfunction

Valvular heart disease (VHD)-related heart failure (HF) is a special subtype of HF with an increasingly concerned heterogeneity in pathophysiology, clinical phenotypes, and outcomes. The mechanism of VHD-related HF involves not only mechanical damage to the valve itself but also valve lesions caused by myocardial ischemia. The interactions between them will lead to the occurrence and development of VHD-related HF subtypes. Due to the spatial (combination of different valvular lesions) and temporal effects (sequence of valvular lesions) of valvular damages, it can make the patient's condition more complicated and also make the physicians deal with a dilemma when deciding on a treatment plan. This indicates that there is still lack of deep understanding on the pathogenic mechanism of VHD-related HF subtypes. On the other hand, mitochondrial dysfunction (MitD) is not only associated with the development of numerous cardiac diseases such as atherosclerosis, hypertension, diabetes, and HF but also occurs in VHD. However, the role of MitD in VHD-related HF is still not fully recognized. In this comprehensive review, we aim to discuss the current findings and challenges of different valvular damages derived from HF subtypes as well as the role of MitD in VHD-related HF subtypes.

Excess ventilation and exertional dyspnoea in heart failure and pulmonary hypertension

Increased ventilation relative to metabolic demands, indicating alveolar hyperventilation and/or increased physiological dead space (excess ventilation), is a key cause of exertional dyspnoea. Excess ventilation has assumed a prominent role in the functional assessment of patients with heart failure (HF) with reduced (HFrEF) or preserved (HFpEF) ejection fraction, pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH). We herein provide the key pieces of information to the caring physician to 1) gain unique insights into the seeds of patients' shortness of breath and 2) develop a rationale for therapeutically lessening excess ventilation to mitigate this distressing symptom. Reduced bulk oxygen transfer induced by cardiac output limitation and/or right ventricle-pulmonary arterial uncoupling increase neurochemical afferent stimulation and (largely chemo-) receptor sensitivity, leading to alveolar hyperventilation in HFrEF, PAH and small-vessel, distal CTEPH. As such, interventions geared to improve central haemodynamics and/or reduce chemosensitivity have been particularly effective in lessening their excess ventilation. In contrast, 1) high filling pressures in HFpEF and 2) impaired lung perfusion leading to ventilation/perfusion mismatch in proximal CTEPH conspire to increase physiological dead space. Accordingly, 1) decreasing pulmonary capillary pressures and 2) mechanically unclogging larger pulmonary vessels (pulmonary endarterectomy and balloon pulmonary angioplasty) have been associated with larger decrements in excess ventilation. Exercise training has a strong beneficial effect across diseases. Addressing some major unanswered questions on the link of excess ventilation with exertional dyspnoea under the modulating influence of pharmacological and nonpharmacological interventions might prove instrumental to alleviate the devastating consequences of these prevalent diseases.

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.

Cardiac Imaging for the Assessment of Left Atrial Mechanics Across Heart Failure Stages

The left atrium (LA) is emerging as a key element in the pathophysiology of several cardiac diseases due to having an active role in contrasting heart failure (HF) progression. Its morphological and functional remodeling occurs progressively according to pressure or volume overload generated by the underlying disease, and its ability of adaptation contributes to avoid pulmonary circulation congestion and to postpone HF symptoms. Moreover, early signs of LA dysfunction can anticipate and predict the clinical course of HF diseases before the symptom onset which, particularly, also applies to patients with increased risk of HF with still normal cardiac structure (stage A HF). The study of LA mechanics (chamber morphology and function) is moving from a research interest to a clinical application thanks to a great clinical, prognostic, and pathophysiological significance. This process is promoted by the technological progress of cardiac imaging which increases the availability of easy-to-use tools for clinicians and HF specialists. Two-dimensional (2D) speckle tracking echocardiography and feature tracking cardiac magnetic resonance are becoming essential for daily practice. In this context, a deep understanding of LA mechanics, its prognostic significance, and the available approaches are essential to improve clinical practice. The present review will focus on LA mechanics, discussing atrial physiology and pathophysiology of main cardiac diseases across the HF stages with specific attention to the prognostic significance. Imaging techniques for LA mechanics assessment will be discussed with an overlook on the dynamic (under stress) evaluation of the chamber.

Pulmonary Hypertension in Patients With Heart Failure With Mid-Range Ejection Fraction

Pulmonary hypertension (PH) is common in patients with heart failure (HF). The role of PH in patients with HF with reduced (HFrEF) and preserved (HFpEF) left ventricular ejection fraction (LVEF) has been extensively characterized during the last years. In contrast, the pathophysiology of HF with mid-range LVEF (HFmrEF), and in particular the role of PH in this context, are largely unknown. There is a paucity of data in this field, and the prevalence of PH, the underlying mechanisms, and the optimal therapy are not well-defined. Although often studied together there is increasing evidence that despite similarities with both HFrEF and HFpEF, HFmrEF also differs from both entities. The present review provides a summary of the current concepts of the mechanisms and clinical impact of PH in patients with HFmrEF, a proposal for the non-invasive and invasive diagnostic approach required to define the pathophysiology of PH and its management, and a discussion of future directions based on insights from mechanistic studies and randomized trials. We also provide an outlook regarding gaps in evidence, future clinical challenges, and research opportunities.

Exercise Intolerance in Heart Failure with Preserved Ejection Fraction

Exercise intolerance represents a typical feature of heart failure with preserved ejection fraction (HFpEF), and is associated with a poor quality of life, frequent hospitalizations, and increased all-cause mortality. The cardiopulmonary exercise test is the best method to quantify exercise intolerance, and allows detection of the main mechanism responsible for the exercise limitation, influencing treatment and prognosis. Exercise training programs improve exercise tolerance in HFpEF. However, studies are needed to identify appropriate type and duration. This article discusses the pathophysiology of exercise limitation in HFpEF, describes methods of determining exercise tolerance class, and evaluates prognostic implications and potential therapeutic strategies.