SPECTRA Phase 2b Study: Impact of Sotatercept on Exercise Tolerance and Right Ventricular Function in Pulmonary Arterial Hypertension.

BACKGROUND: This study aims to assess the impact of sotatercept on exercise tolerance, exercise capacity, and right ventricular function in pulmonary arterial hypertension. METHODS: SPECTRA (Sotatercept Phase 2 Exploratory Clinical Trial in PAH) was a phase 2a, single-arm, open-label, multicenter exploratory study that evaluated the effects of sotatercept by invasive cardiopulmonary exercise testing in participants with pulmonary arterial hypertension and World Health Organization functional class III on combination background therapy. The primary end point was the change in peak oxygen uptake from baseline to week 24. Cardiac magnetic resonance imaging was performed to assess right ventricular function. RESULTS: Among the 21 participants completing 24 weeks of treatment, there was a significant improvement from baseline in peak oxygen uptake, with a mean change of 102.74 mL/min ([95% CIs, 27.72-177.76]; P=0.0097). Sotatercept demonstrated improvements in secondary end points, including resting and peak exercise hemodynamics, and 6-minute walk distance versus baseline measures. Cardiac magnetic resonance imaging showed improvements from baseline at week 24 in right ventricular function. CONCLUSIONS: The clinical efficacy and safety of sotatercept demonstrated in the SPECTRA study emphasize the potential of this therapy as a new treatment option for patients with pulmonary arterial hypertension. Improvements in right ventricular structure and function underscore the potential for sotatercept as a disease-modifying agent with reverse-remodeling capabilities. REGISTRATION: URL: https://www.clinicaltrials.gov; Unique identifier: NCT03738150.

Mismatch between subjective and objective dysautonomia.

Autonomic symptom questionnaires are frequently used to assess dysautonomia. It is unknown whether subjective dysautonomia obtained from autonomic questionnaires correlates with objective dysautonomia measured by quantitative autonomic testing. The objective of our study was to determine correlations between subjective and objective measures of dysautonomia. This was a retrospective cross-sectional study conducted at Brigham and Women's Faulkner Hospital Autonomic Laboratory between 2017 and 2023 evaluating the patients who completed autonomic testing. Analyses included validated autonomic questionnaires [Survey of Autonomic Symptoms (SAS), Composite Autonomic Symptom Score 31 (Compass-31)] and standardized autonomic tests (Valsalva maneuver, deep breathing, sudomotor, and tilt test). The autonomic testing results were graded by a Quantitative scale for grading of cardiovascular reflexes, sudomotor tests and skin biopsies (QASAT), and Composite Autonomic Severity Score (CASS). Autonomic testing, QASAT, CASS, and SAS were obtained in 2627 patients, and Compass-31 in 564 patients. The correlation was strong between subjective instruments (SAS vs. Compass-31, r = 0.74, p < 0.001) and between objective instruments (QASAT vs. CASS, r = 0.81, p < 0.001). There were no correlations between SAS and QASAT nor between Compass-31 and CASS. There continued to be no correlations between subjective and objective instruments for selected diagnoses (post-acute sequelae of COVID-19, n = 61; postural tachycardia syndrome, 211; peripheral autonomic neuropathy, 463; myalgic encephalomyelitis/chronic fatigue syndrome, 95; preload failure, 120; post-treatment Lyme disease syndrome, 163; hypermobile Ehlers-Danlos syndrome, 213; neurogenic orthostatic hypotension, 86; diabetes type II, 71, mast cell activation syndrome, 172; hereditary alpha tryptasemia, 45). The lack of correlation between subjective and objective instruments highlights the limitations of the commonly used questionnaires with some patients overestimating and some underestimating true autonomic deficit. The diagnosis-independent subjective-objective mismatch further signifies the unmet need for reliable screening surveys. Patients who overestimate the symptom burden may represent a population with idiosyncratic autonomic-like symptomatology, which needs further study. At this time, the use of autonomic questionnaires as a replacement of autonomic testing cannot be recommended.

Deep learned representations of the resting 12-lead electrocardiogram to predict at peak exercise.

AIMS: To leverage deep learning on the resting 12-lead electrocardiogram (ECG) to estimate peak oxygen consumption (V˙O2peak) without cardiopulmonary exercise testing (CPET). METHODS AND RESULTS: V ˙ O 2 peak estimation models were developed in 1891 individuals undergoing CPET at Massachusetts General Hospital (age 45 ± 19 years, 38% female) and validated in a separate test set (MGH Test, n = 448) and external sample (BWH Test, n = 1076). Three penalized linear models were compared: (i) age, sex, and body mass index ('Basic'), (ii) Basic plus standard ECG measurements ('Basic + ECG Parameters'), and (iii) basic plus 320 deep learning-derived ECG variables instead of ECG measurements ('Deep ECG-V˙O2'). Associations between estimated V˙O2peak and incident disease were assessed using proportional hazards models within 84 718 primary care patients without CPET. Inference ECGs preceded CPET by 7 days (median, interquartile range 27-0 days). Among models, Deep ECG-V˙O2 was most accurate in MGH Test [r = 0.845, 95% confidence interval (CI) 0.817-0.870; mean absolute error (MAE) 5.84, 95% CI 5.39-6.29] and BWH Test (r = 0.552, 95% CI 0.509-0.592, MAE 6.49, 95% CI 6.21-6.67). Deep ECG-V˙O2 also outperformed the Wasserman, Jones, and FRIEND reference equations (P < 0.01 for comparisons of correlation). Performance was higher in BWH Test when individuals with heart failure (HF) were excluded (r = 0.628, 95% CI 0.567-0.682; MAE 5.97, 95% CI 5.57-6.37). Deep ECG-V˙O2 estimated V˙O2peak <14 mL/kg/min was associated with increased risks of incident atrial fibrillation [hazard ratio 1.36 (95% CI 1.21-1.54)], myocardial infarction [1.21 (1.02-1.45)], HF [1.67 (1.49-1.88)], and death [1.84 (1.68-2.03)]. CONCLUSION: Deep learning-enabled analysis of the resting 12-lead ECG can estimate exercise capacity (V˙O2peak) at scale to enable efficient cardiovascular risk stratification.

Researchers here present data describing a method of estimating exercise capacity from the resting electrocardiogram. Electrocardiogram estimation of exercise capacity was accurate and was found to predict the onset of the wide range of cardiovascular diseases including heart attacks, heart failure, arrhythmia, and death.This approach offers the ability to estimate exercise capacity without dedicated exercise testing and may enable efficient risk stratification of cardiac patients at scale.

Myalgic Encephalomyelitis-Chronic Fatigue Syndrome Common Data Element item content analysis.

INTRODUCTION: Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is a multisystem chronic disease estimated to affect 836,000-2.5 million individuals in the United States. Persons with ME/CFS have a substantial reduction in their ability to engage in pre-illness levels of activity. Multiple symptoms include profound fatigue, post-exertional malaise, unrefreshing sleep, cognitive impairment, orthostatic intolerance, pain, and other symptoms persisting for more than 6 months. Diagnosis is challenging due to fluctuating and complex symptoms. ME/CFS Common Data Elements (CDEs) were identified in the National Institutes of Health (NIH) National Institute of Neurological Disorders and Stroke (NINDS) Common Data Element Repository. This study reviewed ME/CFS CDEs item content. METHODS: Inclusion criteria for CDEs (measures recommended for ME/CFS) analysis: 1) assesses symptoms; 2) developed for adults; 3) appropriate for patient reported outcome measure (PROM); 4) does not use visual or pictographic responses. Team members independently reviewed CDEs item content using the World Health Organization International Classification of Functioning, Disability and Health (ICF) framework to link meaningful concepts. RESULTS: 119 ME/CFS CDEs (measures) were reviewed and 38 met inclusion criteria, yielding 944 items linked to 1503 ICF meaningful concepts. Most concepts linked to ICF Body Functions component (b-codes; n = 1107, 73.65%) as follows: Fatiguability (n = 220, 14.64%), Energy Level (n = 166, 11.04%), Sleep Functions (n = 137, 9.12%), Emotional Functions (n = 131, 8.72%) and Pain (n = 120, 7.98%). Activities and Participation concepts (d codes) accounted for a smaller percentage of codes (n = 385, 25.62%). Most d codes were linked to the Mobility category (n = 69, 4.59%) and few items linked to Environmental Factors (e codes; n = 11, 0.73%). DISCUSSION: Relatively few items assess the impact of ME/CFS symptoms on Activities and Participation. Findings support development of ME/CFS-specific PROMs, including items that assess activity limitations and participation restrictions. Development of psychometrically-sound, symptom-based item banks administered as computerized adaptive tests can provide robust assessments to assist primary care providers in the diagnosis and care of patients with ME/CFS.

Exercise Pathophysiology in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome and Postacute Sequelae of SARS-CoV-2: More in Common Than Not?

TOPIC IMPORTANCE: Postacute sequelae of SARS-CoV-2 (PASC) is a long-term consequence of acute infection from COVID-19. Clinical overlap between PASC and myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) has been observed, with shared symptoms including intractable fatigue, postexertional malaise, and orthostatic intolerance. The mechanistic underpinnings of such symptoms are poorly understood. REVIEW FINDINGS: Early studies suggest deconditioning as the primary explanation for exertional intolerance in PASC. Cardiopulmonary exercise testing reveals perturbations related to systemic blood flow and ventilatory control associated with acute exercise intolerance in PASC, which are not typical of simple detraining. Hemodynamic and gas exchange derangements in PASC have substantial overlap with those observed with ME/CFS, suggestive of shared mechanisms. SUMMARY: This review illustrates exercise pathophysiologic commonalities between PASC and ME/CFS that will help guide future diagnostics and treatment.

Perfusion imaging heterogeneity during NO inhalation distinguishes pulmonary arterial hypertension (PAH) from healthy subjects and has potential as an imaging biomarker.

BACKGROUND: Without aggressive treatment, pulmonary arterial hypertension (PAH) has a 5-year mortality of approximately 40%. A patient's response to vasodilators at diagnosis impacts the therapeutic options and prognosis. We hypothesized that analyzing perfusion images acquired before and during vasodilation could identify characteristic differences between PAH and control subjects. METHODS: We studied 5 controls and 4 subjects with PAH using HRCT and 13NN PET imaging of pulmonary perfusion and ventilation. The total spatial heterogeneity of perfusion (CV2Qtotal) and its components in the vertical (CV2Qvgrad) and cranio-caudal (CV2Qzgrad) directions, and the residual heterogeneity (CV2Qr), were assessed at baseline and while breathing oxygen and nitric oxide (O2 + iNO). The length scale spectrum of CV2Qr was determined from 10 to 110 mm, and the response of regional perfusion to O2 + iNO was calculated as the mean of absolute differences. Vertical gradients in perfusion (Qvgrad) were derived from perfusion images, and ventilation-perfusion distributions from images of 13NN washout kinetics. RESULTS: O2 + iNO significantly enhanced perfusion distribution differences between PAH and controls, allowing differentiation of PAH subjects from controls. During O2 + iNO, CV2Qvgrad was significantly higher in controls than in PAH (0.08 (0.055-0.10) vs. 6.7 × 10-3 (2 × 10-4-0.02), p < 0.001) with a considerable gap between groups. Qvgrad and CV2Qtotal showed smaller differences: - 7.3 vs. - 2.5, p = 0.002, and 0.12 vs. 0.06, p = 0.01. CV2Qvgrad had the largest effect size among the primary parameters during O2 + iNO. CV2Qr, and its length scale spectrum were similar in PAH and controls. Ventilation-perfusion distributions showed a trend towards a difference between PAH and controls at baseline, but it was not statistically significant. CONCLUSIONS: Perfusion imaging during O2 + iNO showed a significant difference in the heterogeneity associated with the vertical gradient in perfusion, distinguishing in this small cohort study PAH subjects from controls.

Neurovascular Dysregulation and Acute Exercise Intolerance in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: A Randomized, Placebo-Controlled Trial of Pyridostigmine.

BACKGROUND: Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is characterized by intractable fatigue, postexertional malaise, and orthostatic intolerance, but its pathophysiology is poorly understood. Pharmacologic cholinergic stimulation was used to test the hypothesis that neurovascular dysregulation underlies exercise intolerance in ME/CFS. RESEARCH QUESTION: Does neurovascular dysregulation contribute to exercise intolerance in ME/CFS, and can its treatment improve exercise capacity? STUDY DESIGN AND METHODS: Forty-five subjects with ME/CFS were enrolled in a single-center, randomized, double-blind, placebo-controlled trial. Subjects were assigned in a 1:1 ratio to receive a 60-mg dose of oral pyridostigmine or placebo after an invasive cardiopulmonary exercise test (iCPET). A second iCPET was performed 50 min later. The primary end point was the difference in peak exercise oxygen uptake (Vo2). Secondary end points included exercise pulmonary and systemic hemodynamics and gas exchange. RESULTS: Twenty-three subjects were assigned to receive pyridostigmine and 22 to receive placebo. The peak Vo2 increased after pyridostigmine but decreased after placebo (13.3 ± 13.4 mL/min vs -40.2 ± 21.3 mL/min; P < .05). The treatment effect of pyridostigmine was 53.6 mL/min (95% CI, -105.2 to -2.0). Peak vs rest Vo2 (25.9 ± 15.3 mL/min vs -60.8 ± 25.6 mL/min; P < .01), cardiac output (-0.2 ± 0.6 L/min vs -1.9 ± 0.6 L/min; P < .05), and right atrial pressure (1.0 ± 0.5 mm Hg vs -0.6 ± 0.5 mm Hg; P < .05) were greater in the pyridostigmine group compared with placebo. INTERPRETATION: Pyridostigmine improves peak Vo2 in ME/CFS by increasing cardiac output and right ventricular filling pressures. Worsening peak exercise Vo2, cardiac output, and right atrial pressure following placebo may signal the onset of postexertional malaise. We suggest that treatable neurovascular dysregulation underlies acute exercise intolerance in ME/CFS. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov; No.: NCT03674541; URL: www. CLINICALTRIALS: gov.

Persistent Exertional Intolerance After COVID-19: Insights From Invasive Cardiopulmonary Exercise Testing.

BACKGROUND: Some patients with COVID-19 who have recovered from the acute infection after experiencing only mild symptoms continue to exhibit persistent exertional limitation that often is unexplained by conventional investigative studies. RESEARCH QUESTION: What is the pathophysiologic mechanism of exercise intolerance that underlies the post-COVID-19 long-haul syndrome in patients without cardiopulmonary disease? STUDY DESIGN AND METHODS: This study examined the systemic and pulmonary hemodynamics, ventilation, and gas exchange in 10 patients who recovered from COVID-19 and were without cardiopulmonary disease during invasive cardiopulmonary exercise testing (iCPET) and compared the results with those from 10 age- and sex-matched control participants. These data then were used to define potential reasons for exertional limitation in the cohort of patients who had recovered from COVID-19. RESULTS: The patients who had recovered from COVID-19 exhibited markedly reduced peak exercise aerobic capacity (oxygen consumption [VO2]) compared with control participants (70 ± 11% predicted vs 131 ± 45% predicted; P < .0001). This reduction in peak VO2 was associated with impaired systemic oxygen extraction (ie, narrow arterial-mixed venous oxygen content difference to arterial oxygen content ratio) compared with control participants (0.49 ± 0.1 vs 0.78 ± 0.1; P < .0001), despite a preserved peak cardiac index (7.8 ± 3.1 L/min vs 8.4±2.3 L/min; P > .05). Additionally, patients who had recovered from COVID-19 demonstrated greater ventilatory inefficiency (ie, abnormal ventilatory efficiency [VE/VCO2] slope: 35 ± 5 vs 27 ± 5; P = .01) compared with control participants without an increase in dead space ventilation. INTERPRETATION: Patients who have recovered from COVID-19 without cardiopulmonary disease demonstrate a marked reduction in peak VO2 from a peripheral rather than a central cardiac limit, along with an exaggerated hyperventilatory response during exercise.

Noninvasive Scale Measurement of Stroke Volume and Cardiac Output Compared With the Direct Fick Method: A Feasibility Study.

Background Objective markers of cardiac function are limited in the outpatient setting and may be beneficial for monitoring patients with chronic cardiac conditions. We assess the accuracy of a scale, with the ability to capture ballistocardiography, electrocardiography, and impedance plethysmography signals from a patient's feet while standing on the scale, in measuring stroke volume and cardiac output compared with the gold-standard direct Fick method. Methods and Results Thirty-two patients with unexplained dyspnea undergoing level 3 invasive cardiopulmonary exercise test at a tertiary medical center were included in the final analysis. We obtained scale and direct Fick measurements of stroke volume and cardiac output before and immediately after invasive cardiopulmonary exercise test. Stroke volume and cardiac output from a cardiac scale and the direct Fick method correlated with r=0.81 and r=0.85, respectively (P<0.001 each). The mean absolute error of the scale estimated stroke volume was -1.58 mL, with a 95% limits of agreement of -21.97 to 18.81 mL. The mean error for the scale estimated cardiac output was -0.31 L/min, with a 95% limits of agreement of -2.62 to 2.00 L/min. The changes in stroke volume and cardiac output before and after exercise were 78.9% and 96.7% concordant, respectively, between the 2 measuring methods. Conclusions In a proof-of-concept study, this novel scale with cardiac monitoring abilities may allow for noninvasive, longitudinal measures of cardiac function. Using the widely accepted form factor of a bathroom scale, this method of monitoring can be easily integrated into a patient's lifestyle.

Postural orthostatic tachycardia syndrome (POTS): Priorities for POTS care and research from a 2019 National Institutes of Health Expert Consensus Meeting - Part 2.

The National Institutes of Health hosted a workshop in 2019 to build consensus around the current state of understanding of the pathophysiology of postural orthostatic tachycardia syndrome (POTS) and to identify knowledge gaps that must be addressed to enhance clinical care of POTS patients through research. This second (of two) articles summarizes current knowledge gaps, and outlines the clinical and research priorities for POTS. POTS is a complex, multi-system, chronic disorder of the autonomic nervous system characterized by orthostatic intolerance and orthostatic tachycardia without hypotension. Patients often experience a host of other related disabling symptoms. The functional and economic impacts of this disorder are significant. The pathophysiology remains incompletely understood. Beyond the significant gaps in understanding the disorder itself, there is a paucity of evidence to guide treatment which can contribute to suboptimal care for this patient population. The vast majority of physicians have minimal to no familiarity or training in the assessment and management of POTS. Funding for POTS research remains very low relative to the size of the patient population and impact of the syndrome. In addition to efforts to improve awareness and physician education, an investment in research infrastructure including the development of standardized disease-specific evaluation tools and outcome measures is needed to facilitate effective collaborative research. A national POTS research consortium could facilitate well-controlled multidisciplinary clinical research studies and therapeutic trials. These priorities will require a substantial increase in the number of research investigators and the amount of research funding in this area.

Postural orthostatic tachycardia syndrome (POTS): State of the science and clinical care from a 2019 National Institutes of Health Expert Consensus Meeting - Part 1.

Postural orthostatic tachycardia syndrome (POTS) is a chronic and often disabling disorder characterized by orthostatic intolerance with excessive heart rate increase without hypotension during upright posture. Patients often experience a constellation of other typical symptoms including fatigue, exercise intolerance and gastrointestinal distress. A typical patient with POTS is a female of child-bearing age, who often first displays symptoms in adolescence. The onset of POTS may be precipitated by immunological stressors such as a viral infection. A variety of pathophysiologies are involved in the abnormal postural tachycardia response; however, the pathophysiology of the syndrome is incompletely understood and undoubtedly multifaceted. Clinicians and researchers focused on POTS convened at the National Institutes of Health in July 2019 to discuss the current state of understanding of the pathophysiology of POTS and to identify priorities for POTS research. This article, the first of two articles summarizing the information discussed at this meeting, summarizes the current understanding of this disorder and best practices for clinical care. The evaluation of a patient with suspected POTS should seek to establish the diagnosis, identify co-morbid conditions, and exclude conditions that could cause or mimic the syndrome. Once diagnosed, management typically begins with patient education and non-pharmacologic treatment options. Various medications are often used to address specific symptoms, but there are currently no FDA-approved medications for the treatment of POTS, and evidence for many of the medications used to treat POTS is not robust.

Insights From Invasive Cardiopulmonary Exercise Testing of Patients With Myalgic Encephalomyelitis/Chronic Fatigue Syndrome.

BACKGROUND: Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) affects tens of millions worldwide; the causes of exertional intolerance are poorly understood. The ME/CFS label overlaps with postural orthostatic tachycardia (POTS) and fibromyalgia, and objective evidence of small fiber neuropathy (SFN) is reported in approximately 50% of POTS and fibromyalgia patients. RESEARCH QUESTION: Can invasive cardiopulmonary exercise testing (iCPET) and PGP9.5-immunolabeled lower-leg skin biopsies inform the pathophysiology of ME/CFS exertional intolerance and potential relationships with SFN? STUDY DESIGN AND METHODS: We analyzed 1,516 upright invasive iCPETs performed to investigate exertional intolerance. After excluding patients with intrinsic heart or lung disease and selecting those with right atrial pressures (RAP) <6.5 mm Hg, results from 160 patients meeting ME/CFS criteria who had skin biopsy test results were compared with 36 control subjects. Rest-to-peak changes in cardiac output (Qc) were compared with oxygen uptake (Qc/VO2 slope) to identify participants with low, normal, or high pulmonary blood flow by Qc/VO2 tertiles. RESULTS: During exercise, the 160 ME/CFS patients averaged lower RAP (1.9 ± 2 vs 8.3 ± 1.5; P < .0001) and peak VO2 (80% ± 21% vs 101.4% ± 17%; P < .0001) than control subjects. The low-flow tertile had lower peak Qc than the normal and high-flow tertiles (88.4% ± 19% vs 99.5% ± 23.8% vs 99.9% ± 19.5% predicted; P < .01). In contrast, systemic oxygen extraction was impaired in high-flow vs low- and normal-flow participants (0.74% ± 0.1% vs 0.88 ± 0.11 vs 0.86 ± 0.1; P < .0001) in association with peripheral left-to-right shunting. Among the 160 ME/CFS patient biopsies, 31% were consistent with SFN (epidermal innervation ≤5.0% of predicted; P < .0001). Denervation severity did not correlate with exertional measures. INTERPRETATION: These results identify two types of peripheral neurovascular dysregulation that are biologically plausible contributors to ME/CFS exertional intolerance-depressed Qc from impaired venous return, and impaired peripheral oxygen extraction. In patients with small-fiber pathology, neuropathic dysregulation causing microvascular dilation may limit exertion by shunting oxygenated blood from capillary beds and reducing cardiac return.

Impact of right ventricular work and pulmonary arterial compliance on peak exercise oxygen uptake in idiopathic pulmonary arterial hypertension.

BACKGROUND: Pulmonary arterial hypertension (PAH) is associated with increased right ventricular (RV) afterload, RV dysfunction and decreased peak oxygen uptake (pVO2). However, the pulmonary hemodynamic mechanisms measured by exercise right heart catheterization (RHC) that contribute to reduced pVO2 in idiopathic PAH (IPAH) are not completely characterized. Therefore, we sought to evaluate the exercise RHC determinants of pVO2 in patients with IPAH. METHODS: 519 consecutive patients with suspected and/or confirmed pulmonary hypertension were prospectively screened to identify 20 patients with IPAH. All IPAH patients were prospectively evaluated with resting and exercise RHC and cardiopulmonary exercise testing. RESULTS: 85% of the patients were female; the median age was 34[29-42] years old. At peak exercise, mean pulmonary arterial (PA) pressure was 76 ± 17 mmHg, PA wedge pressure was 14 ± 5 mmHg, cardiac output (CO) was 5.7 ± 1.9 L/min, pulmonary vascular resistance was 959 ± 401 dynes/s/cm5 and PA compliance was 0.9[0.6-1.2] ml/mmHg. On univariate analysis, pVO2 positively correlated to peak CO, peak cardiac index, peak stroke volume index, peak RV stroke work index (RVSWI) and peak oxygen saturation. There was a negative correlation between pVO2 and Δ (rest to peak change) PA compliance. In age-adjusted multivariate model, peak RVSWI (Coefficient = 0.15, Beta = 0.63, 95% CI [0.07-0.22], p < 0.01) and ΔPA compliance (Coefficient = -2.51, Beta = -0.43, 95% CI [-4.34-(-0.68)], p = 0.01) had the best performance predicting pVO2 (R2 = 0.66). CONCLUSIONS: In conclusion, a load dependent measurement of RV function (RVSWI) and the pulsatile component of RV afterload (ΔPA compliance) significantly influence pVO2 in IPAH, further highlighting the pivotal role of hemodynamic coupling to IPAH exercise capacity.

Sex-Related Differences in Dynamic Right Ventricular-Pulmonary Vascular Coupling in Heart Failure With Preserved Ejection Fraction.

BACKGROUND: Right ventricular (RV) dysfunction is associated with poorer outcomes in heart failure with preserved ejection fraction (HFpEF). Although female subjects are more likely to have HFpEF, male subjects have worse prognosis and resting RV function. The contribution of dynamic RV-pulmonary arterial (RV-PA) coupling between sex and its impact on peak exercise capacity (VO2) in HFpEF is not known. RESEARCH QUESTION: The goal of this study was to investigate the differential effects of sex on RV-PA coupling during maximum incremental exercise in patients with HFpEF. STUDY DESIGN AND METHODS: This study examined rest and exercise invasive pulmonary hemodynamics in 22 male patients with HFpEF and 27 female patients with HFpEF. To further investigate the discrepancy in RV-PA response between sex, 26 age-matched control subjects (11 male subjects and 15 female subjects) were included. Single beat analysis of RV pressure waveforms was used to determine the end-systolic elastance (Ees) and pulmonary arterial elastance. RV-PA coupling was determined as the ratio of end-systolic elastance/PA elastance. RESULTS: Both HFpEF groups experienced decreased peak VO2 (% predicted). However, male patients with HFpEF experienced a greater decrement in peak VO2 compared with female patients (58 ± 16% vs 70 ± 15%; P < .05). Male patients with HFpEF had a more pronounced increase in RV afterload, Ea (1.8 ± 0.6 mm Hg/mL/m2 vs 1.3 ± 0.4 mm Hg/mL/m2; P < .05) and failed to increase RV contractility during exercise, resulting in dynamic RV-PA uncoupling (0.9 ± 0.4 vs 1.2 ± 0.4; P < .05) and subsequent reduced stroke volume index augmentation. In contrast, female patients with HFpEF were able to augment RV contractility in the face of increasing afterload, preserving RV-PA coupling during exercise. INTERPRETATION: Male patients with HFpEF were more compromised regarding dynamic RV-PA uncoupling and reduced peak VO2 compared with female patients. This finding was driven by both RV contractile impairment and afterload mismatch. In contrast, female patients with HFpEF had preserved RV-PA coupling during exercise and better peak exercise VO2 compared with male patients with HFpEF.

Systemic vascular distensibility relates to exercise capacity in connective tissue disease.

OBJECTIVE: Exercise intolerance is a common clinical manifestation of CTD. Frequently, CTD patients have associated cardio-pulmonary disease, including pulmonary hypertension or heart failure that impairs aerobic exercise capacity (pVO2). The contribution of the systemic micro-vasculature to reduced exercise capacity in CTD patients without cardiopulmonary disease has not been fully described. In this study, we sought to examine the role of systemic vascular distensibility, α in reducing exercise capacity (i.e. pVO2) in CTD patients. METHODS: Systemic and pulmonary vascular distensibility, α (%/mmHg) was determined from multipoint systemic pressure-flow plots during invasive cardiopulmonary exercise testing with pulmonary and radial arterial catheters in place in 42 CTD patients without cardiopulmonary disease and compared with 24 age and gender matched normal controls. RESULTS: During exercise, systemic vascular distensibility, α was reduced in CTD patients compared with controls (0.20 ± 0.12%/mmHg vs 0.30 ± 0.13%/mmHg, P =0.01). The reduced systemic vascular distensibility α, was associated with impaired stroke volume augmentation. On multivariate analysis, systemic vascular distensibility, α was associated with a decreased exercise capacity (pVO2) and decreased systemic oxygen extraction. CONCLUSION: Systemic vascular distensibility, α is associated with impaired systemic oxygen extraction and decreased aerobic capacity in patients with CTD without cardiopulmonary disease.

Dynamic right ventricular function response to incremental exercise in pulmonary hypertension.

Pulmonary hypertension is a progressive disease whose survival is linked to adequate right ventricle adaptation to its afterload. In the current study, we performed an in-depth characterization of right ventricle function during maximum incremental exercise in patients with pulmonary hypertension and how it relates to exercise capacity. A total of 377 pulmonary hypertension patients who completed a maximum symptom-limited invasive cardiopulmonary exercise testing were evaluated to identify 45 patients with heart failure with preserved ejection fraction, 48 with exercise pulmonary hypertension, and 47 with established pulmonary arterial hypertension. These patients were compared to 17 age- and gender-matched normal controls. Load-adjusted right ventricle function was quantified as the ratio of right ventricle stroke work index to pulmonary arterial elastance. All patients with pulmonary hypertension had reduced peak VO2 %predicted compared to controls. Right ventricle function deteriorated for all pulmonary hypertension groups by 50% of peak VO2. Worsening of right ventricle function during freewheeling exercise was associated with greater reduction in peak VO2 compared to those whose right ventricle function deteriorated at later exercise stages (i.e. min 1, 2, and 3). On multivariate analysis, reduced ratio of right ventricle stroke work index to arterial elastance was an independent predictor of peak VO2 %predicted (ß-Coefficient -5.46, 95% CI: -9.47 to -1.47, p = 0.01). Right ventricle function deteriorates early during incremental exercise in pulmonary hypertension, occurring by 50% of peak oxygen uptake. The current study demonstrates that right ventricle dysfunction is an early phenomenon during incremental exercise in pulmonary hypertension, occurring by 50% of peak oxygen uptake. The threshold at which right ventricle function is compromised during incremental exercise in pulmonary hypertension influences aerobic capacity and may help guide exercise strategies to mitigate dynamic worsening of right ventricle function during exercise training.

Fick principle and exercise pulmonary hemodynamic determinants of the six-minute walk distance in pulmonary hypertension.

The six-minute walk test is widely used to assess the severity and prognosis of pulmonary hypertension. However, the pathophysiology underlying a compromised six-minute walk distance is incompletely characterized. The purpose of this study is to evaluate the Fick principle and pulmonary hemodynamic determinants of the six-minute walk distance in patients with suspected pulmonary hypertension. Twenty-nine patients were retrospectively studied and underwent a right heart catheterization for the evaluation of suspected pulmonary hypertension. With the pulmonary artery catheter in place, patients were moved to a treadmill and completed a six-minute walk test. Fick cardiac output and indices of right heart afterload were calculated using continuous measurements of pulmonary vascular pressures, gas exchange, and mixed venous blood samples. Fifteen subjects who walked ≤ 348 m were compared to 14 subjects who walked > 348 m. Systemic oxygen delivery was impaired in six-minute walk distance ≤ 348 m compared to six-minute walk distance > 348 m (15.2 ± 6.2 vs. 23.2 ± 6.8 mL/kg/min, p < 0.01). Impaired oxygen delivery was due to a depressed cardiac index and decreased cardiac reserve demonstrated by the change in the stroke volume index (3.0 ± 14 vs. 17 ± 15 mL/min/m2, p = 0.02). The six-minute walk distance positively correlated with oxygen delivery (r = 0.501, p = 0.006) and inversely correlated with oxygen extraction (r = 0.369, p = 0.049). A decreased six-minute walk distance was associated with an increased total pulmonary resistance (r = 0.502, p = 0.006) and pulmonary vascular resistance (r = 0.530, p = 0.003). In patients with suspected pulmonary hypertension, a decreased six-minute walk distance is due to compromised oxygen delivery, decreased cardiac reserve, and increased right ventricular afterload.

Pulmonary Vascular and Right Ventricular Burden During Exercise in Interstitial Lung Disease.

BACKGROUND: Pulmonary hypertension (PH) adversely affects patient's exercise capacity in interstitial lung disease (ILD). The impact of pulmonary vascular and right ventricular (RV) dysfunction, however, has traditionally been believed to be mild and clinically relevant principally in advanced lung disease states. RESEARCH QUESTION: The aim of this study was to evaluate the relative contributions of pulmonary mechanics, pulmonary vascular function, and RV function to the ILD exercise limit. STUDY DESIGN AND METHODS: Forty-nine patients with ILD who underwent resting right heart catheterization followed by invasive exercise testing were evaluated. Patients with PH at rest (ILD + rPH) and with PH diagnosed exclusively during exercise (ILD + ePH) were contrasted with ILD patients without PH (ILD non-PH). RESULTS: Peak oxygen consumption was reduced in ILD + rPH (61 ± 10% predicted) and ILD + ePH (67 ± 13% predicted) compared with ILD non-PH (81 ± 16% predicted; P < .001 and P = .016, respectively). Each ILD hemodynamic phenotype presented distinct patterns of dynamic changes of pulmonary vascular compliance relative to pulmonary vascular resistance from rest to peak exercise. Peak RV stroke work index was increased in ILD + ePH (24.7 ± 8.2 g/m2 per beat) and ILD + rPH (30.9 ± 6.1 g/m2 per beat) compared with ILD non-PH (18.3 ± 6.4 g/m2 per beat; P = .020 and P = .014). Ventilatory reserve was reduced in ILD + rPH compared with the other groups at the anaerobic threshold, but it was similar between ILD + ePH and ILD non-PH at the anaerobic threshold (0.32 ± 0.13 vs 0.30 ± 0.11; P = .921) and at peak exercise (0.70 ± 0.17 vs 0.73 ± 0.24; P = .872). INTERPRETATION: ILD with resting and exercise PH is associated with increased exercise RV work, reduced pulmonary vascular reserve, and reduced peak oxygen consumption. The findings highlight the role of pulmonary vascular and RV burden to ILD exercise limit.

Comprehensive Diagnostic Evaluation of Cardiovascular Physiology in Patients With Pulmonary Vascular Disease: Insights From the PVDOMICS Program.

BACKGROUND: Invasive hemodynamic evaluation through right heart catheterization plays an essential role in the diagnosis, categorization, and risk stratification of patients with pulmonary hypertension. METHODS: Subjects enrolled in the PVDOMICS (Redefining Pulmonary Hypertension through Pulmonary Vascular Disease Phenomics) program undergo an extensive invasive hemodynamic evaluation that includes repeated measurements at rest and during several provocative physiological challenges. It is a National Institutes of Health/National Heart, Lung, and Blood Institute initiative to reclassify pulmonary hypertension groups based on clustered phenotypic and phenomic characteristics. At a subset of centers, participants also undergo an invasive cardiopulmonary exercise test to assess changes in hemodynamics and gas exchange during exercise. CONCLUSIONS: When coupled with other physiological testing and blood -omic analyses involved in the PVDOMICS study, the comprehensive right heart catheterization protocol described here holds promise to clarify the diagnosis and clustering of pulmonary hypertension patients into cohorts beyond the traditional 5 World Symposium on Pulmonary Hypertension groups. This article will describe the methods applied for invasive hemodynamic characterization in the PVDOMICS program. Registration: URL: https://www.clinicaltrials.gov. Unique identifier: NCT02980887.

Metabolomics of exercise pulmonary hypertension are intermediate between controls and patients with pulmonary arterial hypertension.

Mechanisms underlying pulmonary arterial hypertension (PAH) remain elusive. Pulmonary arterial hypertension and exercise PH share similar physiologic consequences; it is debated whether they share biologic mechanisms and if exercise PH represents an early phase of pulmonary arterial hypertension. We conducted an observational study to test if there is a graded metabolic disturbance along the severity of PH, which may indicate shared or disparate pathophysiology. Individuals referred to an academic medical dyspnea center with unexplained exertional intolerance underwent invasive cardiopulmonary exercise testing. We identified controls with no hemodynamic exercise limitation, individuals with exercise PH (mean pulmonary arterial pressure (mPAP) < 25 mmHg at rest but ≥ 30 mmHg during exercise without pulmonary venous hypertension) and pulmonary arterial hypertension (mPAP > 25 mmHg at rest without pulmonary venous hypertension) (n = 26 in each group). Unbiased metabolomics with chromatography mass spectrometry was performed on pulmonary arterial blood at rest and peak exercise. Random forest analysis and hierarchical clustering were used to quantify metabolite prediction of group membership and rank metabolites which were significantly different between groups. Compared to controls, pulmonary arterial hypertension subjects exhibited perturbations in pathways involving glycolysis, TCA cycle, fatty acid and complex lipid oxidation, collagen deposition and fibrosis, nucleotide metabolism, and others. The metabolic signature of exercise PH was uniquely between that of control and pulmonary arterial hypertension subjects. Accuracy predicting control, exercise PH, and pulmonary arterial hypertension group was 96%, 90%, and 88%, respectively, using paired rest-exercise metabolic changes. Our data suggest the metabolic profile of exercise PH is between that of controls and patients with pulmonary arterial hypertension.