Criteria for diagnosis of exercise pulmonary hypertension

Pulmonary Hypertension Associated with Connective Tissue Disease

Pulmonary hypertension (PH), a syndrome characterized by elevated pulmonary pressures, commonly complicates connective tissue disease (CTD) and is associated with increased morbidity and mortality. The incidence of PH varies widely between CTDs; patients with systemic sclerosis are most likely to develop PH. Several different types of PH can present in CTD, including PH related to left heart disease and respiratory disease. Importantly, CTD patients are at risk for developing pulmonary arterial hypertension, a rare form of PH that is associated with high morbidity and mortality. Future therapies targeting pulmonary vascular remodeling may improve outcomes for patients with this devastating disease.

Exercise Hemodynamics Predict Pulmonary Arterial Hypertension in BMPR2 Mutation Carriers

BACKGROUND

Exercise hemodynamics are recommended for early detection of pulmonary arterial hypertension (PAH) and have been suggested to be predictive of future development of PAH in high-risk populations such as BMPR2 mutation carriers. However, the optimal exercise hemodynamic screening parameter remains to be determined. Recent data suggest that pulmonary vascular distensibility coefficient (α) may serve as a useful parameter for early detection of PAH.

RESEARCH QUESTION

What is the value of exercise hemodynamics, including α, for predicting the occurrence of PAH during long-term follow-up in BMPR2 mutation carriers?

STUDY DESIGN AND METHODS

Fifty-two asymptomatic BMPR2 mutation carriers who underwent symptom-limited exercise hemodynamic assessment were followed up for a median of 10 years. The impact of hemodynamics at rest and exercise, presence of exercise pulmonary hypertension, and α on occurrence of PAH during long-term follow-up were assessed.

RESULTS

During long-term follow-up, five patients demonstrated PAH. Patients who demonstrated PAH showed a significantly lower α (0.8 ± 0.4%/mm Hg) than patients without PAH (1.8 ± 0.8%/mm Hg; P = .008). The only hemodynamic parameter that predicted the occurrence of PAH during long-term follow-up at regression analysis was α. Receiver operating characteristic analysis showed that α ≤ 1.5%/mm Hg predicted PAH occurrence with a specificity of 75% and sensitivity of 100%.

INTERPRETATION

Before development of PAH in BMPR2 mutation carriers, α is reduced markedly and may serve as a useful parameter in the setting of early disease detection. Given the low event rate, caution is warranted in interpreting these results, highlighting the need for validation studies.

Pulmonary Hypertension Induced by Right Pulmonary Artery Occlusion: Hemodynamic Consequences of Bmpr2 Mutation

BACKGROUND

The primary genetic risk factor for heritable pulmonary arterial hypertension is the presence of monoallelic mutations in the BMPR2 gene. The incomplete penetrance of BMPR2 mutations implies that additional triggers are necessary for pulmonary arterial hypertension occurrence. Pulmonary artery stenosis directly raises pulmonary artery pressure, and the redirection of blood flow to unobstructed arteries leads to endothelial dysfunction and vascular remodeling. We hypothesized that right pulmonary artery occlusion (RPAO) triggers pulmonary hypertension (PH) in rats with Bmpr2 mutations.

METHODS AND RESULTS

Male and female rats with a 71 bp monoallelic deletion in exon 1 of Bmpr2 and their wild-type siblings underwent acute and chronic RPAO. They were subjected to full high-fidelity hemodynamic characterization. We also examined how chronic RPAO can mimic the pulmonary gene expression pattern associated with installed PH in unobstructed territories. RPAO induced precapillary PH in male and female rats, both acutely and chronically. Bmpr2 mutant and male rats manifested more severe PH compared with their counterparts. Although wild-type rats adapted to RPAO, Bmpr2 mutant rats experienced heightened mortality. RPAO induced a decline in cardiac contractility index, particularly pronounced in male Bmpr2 rats. Chronic RPAO resulted in elevated pulmonary IL-6 (interleukin-6) expression and decreased Gdf2 expression (corrected P value<0.05 and log2 fold change>1). In this context, male rats expressed higher pulmonary levels of endothelin-1 and IL-6 than females.

CONCLUSIONS

Our novel 2-hit rat model presents a promising avenue to explore the adaptation of the right ventricle and pulmonary vasculature to PH, shedding light on pertinent sex- and gene-related effects.

Non-arterial line cardiac output calculation misclassifies exercise pulmonary hypertension and increases risk of data loss particularly in black, scleroderma and Raynaud's patients during invasive exercise testing

BACKGROUND

The direct Fick principle is the standard for calculating cardiac output (CO) to detect CO-dependent conditions like exercise pulmonary hypertension (ePH). Fick COarterial incorporates arterial haemoglobin (Hba) and oxygen saturation (S aO2 ) with oxygen consumption from exercise testing, while Fick COnon-arterial substitutes mixed venous haemoglobin (Hbmv) and peripheral oxygen saturation (S pO2 ) in the absence of an arterial line. The decision to employ an arterial catheter for exercise testing varies, and discrepancies in oxygen saturation and haemoglobin between arterial and non-arterial methods may lead to differences in Fick CO, potentially affecting ePH classification.

METHODS

We performed a retrospective analysis of 296 consecutive invasive cardiopulmonary exercise testing (iCPET) studies comparing oxygen saturation from pulse oximetry (S pO2 ) and radial arterial (S aO2 ), Hba and Hbmv, and CO calculated with arterial (COarterial) and non-arterial (COnon-arterial) values. We assessed the risk of misclassification of pre- and post-capillary ePH and data loss due to inaccurate S pO2 .

RESULTS

When considering all stages from rest to peak exercise, Hba and Hbmv demonstrated high correlation, while S pO2 and S aO2 as well as COarterial and COnon-arterial demonstrated low correlation. Data loss was significantly higher across all stages of exercise for S pO2 (n=346/1926 (18%)) compared to S aO2 (n=17/1923 (0.88%)). We found that pre- and post-capillary ePH were misclassified as COnon-arterial data (n=7/41 (17.1%) and n=2/23 (8.7%), respectively). Patients with scleroderma and/or Raynaud's (n=11/33 (33.3%)) and black patients (n=6/19 (31.6%)) had more S pO2 data loss.

CONCLUSION

Reliance upon S pO2 during invasive exercise testing results in the misclassification of pre- and post-capillary ePH, and unmeasurable S pO2 for black, scleroderma and Raynaud's patients can preclude accurate exercise calculations, thus limiting the diagnostic and prognostic value of invasive exercise testing without an arterial line.

Nitroprusside Combined with Leg Raise at the Time of Right Heart Catheterization to Differentiate Precapillary from Other Hemodynamic Forms of Pulmonary Hypertension: A Single-Center Pilot Study

Pulmonary hypertension (PH) can arise from several distinct disease processes, with a percentage presenting with combined pre- and postcapillary pulmonary hypertension (cpcPH). Patients with cpcPH are unsuitable candidates for PH-directed therapies due to elevated pulmonary capillary wedge pressures (PCWPs); however, the PCWP is dynamic and is affected by both preload and afterload. Many patients that are diagnosed with cpcPH are hypertensive at the time of right heart catheterization which has the potential to increase the PCWP and, therefore, mimic a more postcapillary-predominant phenotype. In this small pilot study, we examine the effect of nitroprusside combined with dynamic preload augmentation with a passive leg raise maneuver in hypertensive cpcPH patients at the time of right heart catheterization to identify a more precapillary-dominant PH phenotype. Patients that met the criteria of PCWP ≤ 15 mmHg with nitroprusside infusion and PCWP ≤ 18 mmHg with nitroprusside infusion and simultaneous leg raise were started on pulmonary vascular-targeted therapy. Long-term PH therapy was well tolerated, with increased six-minute walk distance, improved WHO functional class, decreased NT-proBNP, and improved REVEAL 2.0 Lite Risk Score in this precapillary-dominant PH phenotype. This small study highlights the importance of characterizing patient physiology beyond resting conditions at the time of right heart catheterization.

Phenotyping exercise limitation of patients with Interstitial Fibrosing Lung Disease: the importance of exercise hemodynamics

INTRODUCTION AND OBJECTIVE

Left-heart dysfunction and pulmonary vasculopathy are increasingly recognized as contributing factors of exercise capacity limitation in interstitial fibrosing lung disease (IFLD). Moreover, the clinical significance of exercise pulmonary hypertension (ePH) in pulmonary and cardiac diseases has been documented, representing a risk factor for decreased exercise capacity and survival, progression to resting pulmonary hypertension (PH) and overall clinical worsening. We conducted a prospective study aiming at: (a) assessing the prevalence of PH and ePH in a cohort of 40 functionally limited patients with IFLD, (b) determining the post-capillary (postC) or pre-capillary (preC) etiology of either PH or ePH in this cohort, and (c) examining the correlations between invasively and non-invasively measured exercise variables among hemodynamic groups.

PATIENTS AND METHODS

40 IFLD patients underwent cardiopulmonary evaluation, including: clinical examination, lung function tests, 6-minute walking test, heart ultrasonography, cardiopulmonary exercise test and, finally, right heart catheterization (RHC). Resting hemodynamic evaluation was followed by the exercise protocol proposed by Herve et al, using a bedside cycle ergometer in the supine position. Abnormal elevation of mean pulmonary artery pressure (mPAP) above 30mmHg during exercise, with respect to abnormal elevation of cardiac output (CO) below 10 L/min (mPAP-CO ratio ⩾3 mmHg·min·L-1) was used to define ePH (Herve et al, 2015). Secondary hemodynamic evaluation involved detection of abnormal pulmonary arterial wedge pressure (PAWP) increase at peak exercise in relation to CO. Specifically, ΔPAWP/ΔCO >2 mmHg/L per minute determined an abnormal PAWP elevation (Bentley et al, 2020).

RESULTS

Among the 40-patient cohort, 25% presented postC PH, 37.5% preC PH, 27.5% ePH, with the remaining 10% recording normal hemodynamics. PAWP evaluation during exercise revealed a postC etiology in 4 out of the 11 patients presenting ePH, and a postC etiology in 6 out of the 15 patients presenting resting preC PH. Mean values of non-invasive variables did not display statistically significant differences among hemodynamic groups, except for: diffusing capacity for carbon monoxide (DLCO), carbon monoxide transfer coefficient (KCO) and the ratio of functional vital capacity to DLCO (FVC%/DLCO%), which were lower in both ePH and PH groups (p < 0.05). Resting values of CO, cardiac index (CI), stroke volume (SV) and pulmonary vascular compliance (PVC) were significantly impaired in ePH, preC-PH and postC-PH groups when compared to the normal group.

CONCLUSIONS

Both PH and ePH were highly prevalent within the IFLD patient group, suggesting that RHC should be offered more frequently in functionally limited patients. Diffusion capacity markers must thus guide decision making, in parallel to clinical evaluation. ePH was associated to lower resting CO and PVC, in a similar way to resting PH, indicating the relevance of cardiopulmonary function to exercise limitation. Finally, the use of the ΔPAWP/ΔCO>2 criterion further uncovered PH of postcapillary etiology, highlighting the complexity of hemodynamics in IFLD.

CLINICALTRIALS

gov ID: NCT03706820.

Exercise Testing in Patients with Pulmonary Hypertension

Pulmonary hypertension (PH), defined by a mean pulmonary artery pressure of >20 mm Hg, often presents with non-specific symptoms such as dyspnea and exercise intolerance, making it difficult to diagnose early before the onset of right heart dysfunction. Therefore, exercise testing can be of great utility for clinicians who are evaluating patients with an unclear etiology of exercise intolerance by helping identify the underlying mechanisms of their disease. The presence of PH is associated with adverse clinical outcomes, with distinct differences and patterns in the cardiovascular and ventilatory responses to exercise across various PH phenotypes. We discuss the role of exercise-invasive hemodynamic testing, cardiopulmonary exercise testing, and exercise stress echocardiography modalities across the spectrum of PH.

Transcriptional profiles of pulmonary artery endothelial cells in pulmonary hypertension

Pulmonary arterial hypertension (PAH) is characterized by endothelial cell (EC) dysfunction. There are no data from living patients to inform whether differential gene expression of pulmonary artery ECs (PAECs) can discern disease subtypes, progression and pathogenesis. We aimed to further validate our previously described method to propagate ECs from right heart catheter (RHC) balloon tips and to perform additional PAEC phenotyping. We performed bulk RNA sequencing of PAECs from RHC balloons. Using unsupervised dimensionality reduction and clustering we compared transcriptional signatures from PAH to controls and other forms of pulmonary hypertension. Select PAEC samples underwent single cell and population growth characterization and anoikis quantification. Fifty-four specimens were analyzed from 49 subjects. The transcriptome appeared stable over limited passages. Six genes involved in sex steroid signaling, metabolism, and oncogenesis were significantly upregulated in PAH subjects as compared to controls. Genes regulating BMP and Wnt signaling, oxidative stress and cellular metabolism were differentially expressed in PAH subjects. Changes in gene expression tracked with clinical events in PAH subjects with serial samples over time. Functional assays demonstrated enhanced replication competency and anoikis resistance. Our findings recapitulate fundamental biological processes of PAH and provide new evidence of a cancer-like phenotype in ECs from the central vasculature of PAH patients. This "cell biopsy" method may provide insight into patient and lung EC heterogeneity to advance precision medicine approaches in PAH.

Updated Hemodynamic Definition and Classification of Pulmonary Hypertension

Pulmonary hypertension (PH) is a pathophysiological manifestation of a heterogeneous group of diseases characterized by abnormally elevated pulmonary arterial pressures diagnosed on right heart catheterization. The 2022 European Society of Cardiology (ESC) and European Respiratory Society (ERS) Guidelines for the diagnosis and treatment of PH provides a new hemodynamic definition to define PH by lowering the threshold of the mean pulmonary artery pressure (mPAP) to 20 mm Hg. Precapillary PH is thus now defined as a mPAP >20 mm Hg together with a normal pulmonary artery wedge pressure (<15 mm Hg) and an increased pulmonary vascular resistance (>2 Wood Units). The ESC/ERS 2022 Guidelines also introduce a revised clinical classification of PH while retaining its previous distinction between the five groups according to the underlying pathophysiology.

Pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a rare and progressive disease characterised by remodelling of the pulmonary arteries and progressive narrowing of the pulmonary vasculature. This leads to a progressive increase in pulmonary vascular resistance and pulmonary arterial pressure and, if left untreated, to right ventricular failure and death. A correct diagnosis requires a complete work-up including right heart catheterisation performed in a specialised centre. Although our knowledge of the epidemiology, pathology and pathophysiology of the disease, as well as the development of innovative therapies, has progressed in recent decades, PAH remains a serious clinical condition. Current treatments for the disease target the three specific pathways of endothelial dysfunction that characterise PAH: the endothelin, nitric oxide and prostacyclin pathways. The current treatment algorithm is based on the assessment of severity using a multiparametric risk stratification approach at the time of diagnosis (baseline) and at regular follow-up visits. It recommends the initiation of combination therapy in PAH patients without cardiopulmonary comorbidities. The choice of therapy (dual or triple) depends on the initial severity of the condition. The main treatment goal is to achieve low-risk status. Further escalation of treatment is required if low-risk status is not achieved at subsequent follow-up assessments. In the most severe patients, who are already on maximal medical therapy, lung transplantation may be indicated. Recent advances in understanding the pathophysiology of the disease have led to the development of promising emerging therapies targeting dysfunctional pathways beyond endothelial dysfunction, including the TGF-β and PDGF pathways.

Right Heart Adaptation to Exercise in Pulmonary Hypertension: An Invasive Hemodynamic Study

BACKGROUND

Right heart failure (RHF) is associated with a dismal prognosis in patients with pulmonary hypertension (PH). Exercise right heart catheterization may unmask right heart maladaptation as a sign of RHF. We sought to (1) define the normal limits of right atrial pressure (RAP) increase during exercise; (2) describe the right heart adaptation to exercise in PH owing to heart failure with preserved ejection fraction (PH-HFpEF) and in pulmonary arterial hypertension (PAH); and (3) identify the factors associated with right heart maladaptation during exercise.

METHODS AND RESULTS

We analyzed rest and exercise right heart catheterization from patients with PH-HFpEF and PAH. Right heart adaptation was described by absolute or cardiac output (CO)-normalized changes of RAP during exercise. Individuals with noncardiac dyspnea (NCD) served to define abnormal RAP responses (>97.5th percentile). Thirty patients with PH-HFpEF, 30 patients with PAH, and 21 patients with NCD were included. PH-HFpEF were older than PAH, with more cardiovascular comorbidities, and a higher prevalence of severe tricuspid regurgitation (P < .05). The upper limit of normal for peak RAP and RAP/CO slope in NCD were >12 mm Hg and ≥1.30 mm Hg/L/min, respectively. PH-HFpEF had higher peak RAP and RAP/CO slope than PAH (20 mm Hg [16-24 mm Hg] vs 12 mm Hg [9-19 mm Hg] and 3.47 mm Hg/L/min [2.02-6.19 mm Hg/L/min] vs 1.90 mm Hg/L/min [1.01-4.29 mm Hg/L/min], P < .05). A higher proportion of PH-HFpEF had RAP/CO slope and peak RAP above normal (P < .001). Estimated stressed blood volume at peak exercise was higher in PH-HFpEF than PAH (P < .05). In the whole PH cohort, the RAP/CO slope was associated with age, the rate of increase in estimated stressed blood volume during exercise, severe tricuspid regurgitation, and right atrial dilation.

CONCLUSIONS

Patients with PH-HFpEF display a steeper increase of RAP during exercise than those with PAH. Preload-mediated mechanisms may play a role in the development of exercise-induced RHF.

Role of cardiopulmonary exercise test in early diagnosis of pulmonary hypertension in scleroderma patients

INTRODUCTION

Pulmonary arterial hypertension (PAH) is a severe, high mortality and progressive disease. Early diagnosis and treatment improves the prognosis. Patients with scleroderma disease presents high risk of developing PAH. Established screening strategies - echocardiogram and DETECT algorithm - recognize the disease when it is already advanced. Cardiopulmonary exercise testing (CPET) detects pulmonary vascular injury in earlier stages.

METHODS

Prospective study of 52 consecutive patients diagnosed of scleroderma in our health area, during 2 years (2018 and 2019). All of them undergo CPET, in addition to the annual systematic screening. Sensitivity of current PAH screening is compared to CPET. To confirm the presence of PAH, right heart catheterization (RHC) is performed. In case of suspected PAH in CPET, but non-confirmatory right heart catheterization at rest, patients carried out exercise RHC.

RESULTS

Fifty-two CPET were performed, of which 16 suggested PAH. Resting RHC confirmed PAH in 5 patients and exercise RHC in 7 (diagnostic sensitivity of CPET together with rest and exercise catheterization of 100%). Of these 16 patients, DETECT had identified 10, of whom resting RHC confirmed PAH in 3 and exercise RHC in 2 (guideline-based diagnostic algorithm sensitivity 70%).

CONCLUSIONS

CPET and exercise RHC could detect PAH earlier than established screening in patients with scleroderma disease, allowing early diagnosis.

A comparative study on the diagnostic efficacy of different diagnostic criteria for exercise pulmonary hypertension

BACKGROUND

Exercise pulmonary hypertension (ePH) has three common diagnostic criteria: the mean pulmonary artery pressure (mPAP) > 30 mmHg and total pulmonary resistance (TPR) at peak exercise >3 Wood units ("Joint criteria"), the mPAP/cardiac output (CO) slope of the two-point measurement (ΔmPAP/ΔCO) > 3 mmHg/L/min ("Two-point criteria"), and the mPAP/CO slope of the multi-point data >3 mmHg/L/min ("Multi-point criteria"). We compared the diagnostic efficacy of these criteria, which remain controversial.

METHODS

Following resting right heart catheterization (RHC), all patients underwent exercise RHC (eRHC). The patients were divided into different ePH and non-exercise pulmonary hypertension (nPH) groups according to the above criteria. Joint criteria were used as the reference to compare the other two, namely diagnostic concordance, sensitivity and specificity. We conducted further analysis to determine the correlation between different diagnostic criteria grouping and the clinical severity of PH.

RESULTS

Thirty-three patients with mPAP_rest ≤ 20 mmHg were enrolled. a) Diagnostic concordance, sensitivity and specificity: compared with Joint criteria, the diagnostic concordances of Two-point criteria and Multi-point criteria were 78.8% (κ = 0.570, P < 0.01) and 90.9% (κ = 0.818, P < 0.01), respectively; the sensitivity of Two-point criteria was high (100%), but the specificity was poor (56.3%); however, Multi-point criteria exhibited higher sensitivity (94.1%) and specificity (87.5%). b) Clinically relevant analysis: a significant difference was observed in several clinical severity indicators between ePH and nPH patients according to Multi-point criteria grouping(all P < 0.05).

CONCLUSION

Multi-point criteria are more clinically relevant and provide better diagnostic efficiency.

Incremental diagnostic value of post-exercise lung congestion in heart failure with preserved ejection fraction

AIMS

Lung ultrasound (LUS) may unmask occult heart failure with preserved ejection fraction (HFpEF) by demonstrating an increase in extravascular lung water (EVLW) during exercise. Here, we sought to examine the dynamic changes in ultrasound B-lines during exercise to identify the optimal timeframe for HFpEF diagnosis.

METHODS AND RESULTS

Patients with HFpEF (n = 134) and those without HF (controls, n = 121) underwent a combination of exercise stress echocardiography and LUS with simultaneous expired gas analysis to identify exercise EVLW. Exercise EVLW was defined by B-lines that were newly developed or increased during exercise. The E/e' ratio peaked during maximal exercise and immediately decreased during the recovery period in patients with HFpEF. Exercise EVLW was most prominent during the recovery period in patients with HFpEF, while its prevalence did not increase from peak exercise to the recovery period in controls. Exercise EVLW was associated with a higher E/e' ratio and pulmonary artery pressure, lower right ventricular systolic function, and elevated minute ventilation to carbon dioxide production (VE vs. VCO2) slope during peak exercise. Increases in B-lines from rest to the recovery period provided an incremental diagnostic value to identify HFpEF over the H2FPEF score and resting left atrial reservoir strain.

CONCLUSION

Exercise EVLW was most prominent early during the recovery period; this may be the optimal timeframe for imaging ultrasound B-lines. Exercise stress echocardiography with assessments of recovery EVLW may enhance the diagnosis of HFpEF.

Hemodynamic Responses to Provocative Maneuvers during Right Heart Catheterization

Rationale: Current guidelines recognize the utility of provocative maneuvers during right heart catheterization to aid the diagnosis of pulmonary hypertension. Few studies have compared the performance of different provocation maneuvers. Objectives: To assess the hemodynamic correlation among three provocative maneuvers, including their effect on pulmonary hypertension classification. Methods: This prospective trial was conducted between October 2016 and May 2018. Adult patients underwent three provocative maneuvers during right heart catheterization: passive leg raise (PLR), load-targeted supine bicycle exercise, and rapid crystalloid fluid infusion. Patients were classified as follows: no pulmonary hypertension, precapillary pulmonary hypertension, isolated postcapillary pulmonary hypertension, combined pre- and postcapillary pulmonary hypertension, and uncategorized pulmonary hypertension. We assessed the hemodynamic changes associated with each maneuver. We also assessed whether provocative maneuvers led to hemodynamic reclassification of the patient to either postcapillary pulmonary hypertension with provocation or exercise pulmonary hypertension. Results: Eighty-five patients (mean age 62 ± 12 years, 53% women) were included. Correlation between exercise and fluid challenge was moderate to strong (0.49-0.82; P < 0.001) for changes in right atrial pressure, mean pulmonary arterial pressure, pulmonary arterial wedge pressure, and cardiac index from baseline. Correlation between PLR and exercise (0.4-0.65; P < 0.001) and between PLR and fluid challenge (0.45-0.6; P < 0.001) was moderate for changes in right atrial pressure, mean pulmonary arterial pressure, pulmonary arterial wedge pressure, pulmonary vascular resistance, and cardiac index. Hemodynamic correlation between other provocative maneuvers was poor. Depending on provocative maneuver and classification criteria, there was significant variation in the number of patients reclassified as having exercise pulmonary hypertension (3-50%) or postcapillary pulmonary hypertension with provocation (11-48%). Conclusions: Hemodynamic determinations during exercise and fluid challenge showed moderate to strong hemodynamic correlation. Moderate hemodynamic correlation was seen between PLR and exercise or fluid challenge. Although some provocative maneuvers demonstrate good hemodynamic correlation, there is inconsistency when using these maneuvers to identify patients with postcapillary or exercise pulmonary hypertension.

Pulmonary vascular disease and exercise hemodynamics in chronic liver disease

BACKGROUND & AIMS

Portopulmonary hypertension (POPH) and hepatopulmonary syndrome (HPS) are severe pulmonary vascular complications of chronic liver disease and strongly associated with morbidity and mortality. The prevalence of these complications is relatively high in patients evaluated for liver transplantation, however it is virtually unknown in patients with stable chronic liver disease.

METHODS

We assessed the pulmonary hypertension (PH) and HPS prevalence in a prospective registry study of our liver out-patient clinic in a tertiary center. Between 2011 and 2016, consecutive patients with cirrhosis or non-cirrhotic portal hypertension were prospectively enrolled after written informed consent. We excluded patients with acute decompensation of liver disease and other causes of PH like severe chronic heart or lung diseases and chronic thromboembolic PH. HPS was diagnosed using contrast enhanced echocardiography and blood gas analysis. Patients were screened for PH using an algorithm implementing severity of dyspnea, echocardiography, cardiopulmonary exercise testing and exercise echocardiography employing a threshold of systolic pulmonary arterial pressure (SPAP) = 50 mmHg at peak exercise. If the algorithm indicated an increased PH risk, patients were invited for invasive investigations by means of right heart and hepatic vein catheter. We defined POPH as resting mPAP≥21 mmHg and PVR>3WU and PAWP<15 mmHg, mild PH as resting mPAP = 21-24 mmHg, and exercise PH as mPAP>30 mmHg and TPR >3 WU at peak exercise.

RESULTS

Two-hundred-five patients were enrolled (male 75%; cirrhosis 96%; median age 57 yrs). Sixty-seven patients (33%) fulfilled HPS criteria but only two (1.0%) for severe (PaO2:50-60 mmHg) or very severe HPS (PaO2<50 mmHg). In 18/77 patients (23%) undergoing exercise echocardiography, SPAP at peak exercise exceeded 50 mmHg. Finally, n = 3 (1.5%) patients were invasively diagnosed with POPH, n = 4 (2.9%) with mild PH and n = 2 with exercise PH.

CONCLUSION

In chronic liver disease, excluding acute decompensation and other causes of PH, POPH and severe HPS are rare findings while mild to moderate HPS and mild PH or exercise PH are more frequent.

Exercise metabolomics in pulmonary arterial hypertension: Where pulmonary vascular metabolism meets exercise physiology

Pulmonary arterial hypertension is an incurable disease marked by dysregulated metabolism, both at the cellular level in the pulmonary vasculature, and at the whole-body level characterized by impaired exercise oxygen consumption. Though both altered pulmonary vascular metabolism and abnormal exercise physiology are key markers of disease severity and pulmonary arterial remodeling, their precise interactions are relatively unknown. Herein we review normal pulmonary vascular physiology and the current understanding of pulmonary vascular cell metabolism and cardiopulmonary response to exercise in Pulmonary arterial hypertension. We additionally introduce a newly developed international collaborative effort aimed at quantifying exercise-induced changes in pulmonary vascular metabolism, which will inform about underlying pathophysiology and clinical management. We support our investigative approach by presenting preliminary data and discuss potential future applications of our research platform.

Emerging phenotypes of pulmonary hypertension associated with COPD: a field guide

PURPOSE OF REVIEW

Pulmonary hypertension (PH) is a common complication of chronic obstructive lung disease (COPD), but clinical presentation is variable and not always 'proportional' to the severity of the obstructive disease. This review aims to analyze heterogeneity in clinical features of PH-COPD, providing a guide for diagnosis and management according to phenotypes.

RECENT FINDINGS

Recent works have focused on severe PH in COPD, providing insights into the characteristics of patients with predominantly vascular disease. The recently recognized 'pulmonary vascular phenotype', characterized by severe PH and mild airflow obstruction with severe hypoxemia, has markedly worse prognosis and may be a candidate for large trials with pulmonary vasodilators. In severe PH, which might be best described by a pulmonary vascular resistance threshold, there may also be a need to distinguish patients with mild COPD (pulmonary vascular phenotype) from those with severe COPD ('Severe COPD-Severe PH' phenotype).

SUMMARY

Correct phenotyping is key to appropriate management of PH associated with COPD. The lack of evidence regarding the use of pulmonary vasodilators in PH-COPD may be due to the existence of previously unrecognized phenotypes with different responses to therapy. This review offers the clinician caring for patients with COPD and PH a phenotype-focused approach to diagnosis and management, aimed at personalized care.

Elucidating the Clinical Implications and Pathophysiology of Pulmonary Hypertension in Heart Failure With Preserved Ejection Fraction: A Call to Action: A Science Advisory From the American Heart Association

This science advisory focuses on the need to better understand the epidemiology, pathophysiology, and treatment of pulmonary hypertension in patients with heart failure with preserved ejection fraction. This clinical phenotype is important because it is common, is strongly associated with adverse outcomes, and lacks evidence-based therapies. Our goal is to clarify key knowledge gaps in pulmonary hypertension attributable to heart failure with preserved ejection fraction and to suggest specific, actionable scientific directions for addressing such gaps. Areas in need of additional investigation include refined disease definitions and interpretation of hemodynamics, as well as greater insights into noncardiac contributors to pulmonary hypertension risk, optimized animal models, and further molecular studies in patients with combined precapillary and postcapillary pulmonary hypertension. We highlight translational approaches that may provide important biological insight into pathophysiology and reveal new therapeutic targets. Last, we discuss the current and future landscape of potential therapies for patients with heart failure with preserved ejection fraction and pulmonary vascular dysfunction, including considerations of precision medicine, novel trial design, and device-based therapies, among other considerations. This science advisory provides a synthesis of important knowledge gaps, culminating in a collection of specific research priorities that we argue warrant investment from the scientific community.

Comparison between thermodilution and Fick methods for resting and exercise-induced cardiac output measurement in patients with chronic dyspnea

Studies comparing thermodilution (TD) and the direct Fick method (dFM) for cardiac output (CO) measurement are rare. We compared CO measurements between TD (2-5 cold water injections), the dFM, and indirect Fick method (iFM) at rest and during exercise, and assessed the effect of averaging different numbers of TD measurements during exercise. This retrospective study included 300 patients (52.3% women, mean age 66 ± 11 years) having pulmonary hypertension (76.0%) or unexplained dyspnea. Invasive hemodynamic and gas exchange parameters were measured at rest (supine; n = 300) and during unloaded cycling (semi-supine; n = 275) and 25-W exercise (semi-supine; n = 240). All three methods showed significant differences in CO measurement (ΔCO) at rest (p ≤ 0.001; ΔCO > 1 L/min: 45.0% [iFM vs. dFM], 42.0% [iFM vs. TD], and 45.7% [TD vs. dFM]). ΔCO (TD vs. dFM) was significant during unloaded cycling (p < 0.001; ΔCO > 1 L/min: 56.6%) but not during 25-W exercise (p = 0.137; ΔCO > 1 L/min: 52.8%). ΔCO (TD vs. dFM) during 25-W exercise was significant when using one or two (p ≤ 0.01) but not three (p = 0.06) TD measurements. Mean ΔCO (TD [≥3 measurements] vs. dFM) was -0.43 ± 1.98 and -0.06 ± 2.29 L/min during unloaded and 25-W exercise, respectively. Thus, TD and dFM CO measurements are comparable during 25-W exercise (averaging ≥3 TD measurements), but not during unloaded cycling or at rest. Individual ΔCOs vary substantially and require critical interpretation to avoid CO misclassification.

Distinguishing exercise intolerance in early-stage pulmonary hypertension with invasive exercise hemodynamics: Rest VE /VCO2 and ETCO2 identify pulmonary vascular disease

BACKGROUND

Among subjects with exercise intolerance and suspected early-stage pulmonary hypertension (PH), early identification of pulmonary vascular disease (PVD) with noninvasive methods is essential for prompt PH management.

HYPOTHESIS

Rest gas exchange parameters (minute ventilation to carbon dioxide production ratio: VE /VCO2 and end-tidal carbon dioxide: ETCO2 ) can identify PVD in early-stage PH.

METHODS

We conducted a retrospective review of 55 subjects with early-stage PH (per echocardiogram), undergoing invasive exercise hemodynamics with cardiopulmonary exercise test to distinguish exercise intolerance mechanisms. Based on the rest and exercise hemodynamics, three distinct phenotypes were defined: (1) PVD, (2) pulmonary venous hypertension, and (3) noncardiac dyspnea (no rest or exercise PH). For all tests, *p < .05 was considered statistically significant.

RESULTS

The mean age was 63.3 ± 13.4 years (53% female). In the overall cohort, higher rest VE /VCO2 and lower rest ETCO2 (mm Hg) correlated with high rest and exercise pulmonary vascular resistance (PVR) (r ~ 0.5-0.6*). On receiver-operating characteristic analysis to predict PVD (vs. non-PVD) subjects with noninvasive metrics, area under the curve for pulmonary artery systolic pressure (echocardiogram) = 0.53, rest VE /VCO2  = 0.70* and ETCO2  = 0.73*. Based on this, optimal thresholds of rest VE /VCO2  > 40 mm Hg and rest ETCO2  < 30 mm Hg were applied to the overall cohort. Subjects with both abnormal gas exchange parameters (n = 12, vs. both normal parameters, n = 19) had an exercise PVR 5.2 ± 2.6* (vs. 1.9 ± 1.2), mPAP/CO slope with exercise 10.2 ± 6.0* (vs. 2.9 ± 2.0), and none included subjects from the noncardiac dyspnea group.

CONCLUSIONS

In a broad cohort of subjects with suspected early-stage PH, referred for invasive exercise testing to distinguish mechanisms of exercise intolerance, rest gas exchange parameters (VE /VCO2  > 40 mm Hg and ETCO2  < 30 mm Hg) identify PVD.

Diastolic Filling Time, Chronotropic Response, and Exercise Capacity in Heart Failure and Preserved Ejection Fraction With Sinus Rhythm

Background

Exercise‐induced high heart rate may impair exercise tolerance by reducing diastolic filling time and ventricular filling in heart failure with preserved ejection fraction (HFpEF). Given the importance of chronotropic response, we hypothesized that reduction in diastolic filling time because of exercise‐induced increased heart rate would not impair cardiac output reserve and exercise capacity. We sought to determine the association between heart rate, diastolic filling time, hemodynamics, and exercise capacity in HFpEF.

Methods and Results

Patients with HFpEF (n=66) and controls without HF (n=107) underwent bicycle exercise echocardiography with simultaneous expired gas analysis to measure oxygen consumption. Diastolic filling time was assessed by the overlap time between mitral E‐ and A‐waves (longer overlap time indicates shorter diastolic filling duration). Overlap time increased (ie, diastolic filling time shortened) in HFpEF and controls as heart rate increased with exercise, and the relationship was similar between the groups. Greater heart rate response correlated with higher cardiac output (r=0.51, P<0.0001) and oxygen consumption (r=0.50, P<0.0001) during peak exercise. Shorter diastolic filling time, as assessed by longer overlap time, was correlated with higher cardiac output (r=0.47, P<0.0001) and peak oxygen consumption (r=0.38, P=0.007), not with E/e′ or right ventricular‐pulmonary artery uncoupling. Longer overlap time was associated with mitral A velocity (r=0.53, P<0.0001) and left atrial booster pump strain (r=0.42, P<0.0001).

Conclusions

Shortening of diastolic filling interval in tandem with increased heart rate during exercise does not limit cardiac output reserve or exercise capacity in HFpEF.

Deep Learning for Detection of Exercise-Induced Pulmonary Hypertension Using Chest X-Ray Images

Background

Stress echocardiography is an emerging tool used to detect exercise-induced pulmonary hypertension (EIPH). However, facilities that can perform stress echocardiography are limited by issues such as cost and equipment.

Objective

We evaluated the usefulness of a deep learning (DL) approach based on a chest X-ray (CXR) to predict EIPH in 6-min walk stress echocardiography.

Methods

The study enrolled 142 patients with scleroderma or mixed connective tissue disease with scleroderma features who performed a 6-min walk stress echocardiographic test. EIPH was defined by abnormal cardiac output (CO) responses that involved an increase in mean pulmonary artery pressure (mPAP). We used the previously developed AI model to predict PH and calculated PH probability in this cohort.

Results

EIPH defined as ΔmPAP/ΔCO >3.3 and exercise mPAP >25 mmHg was observed in 52 patients, while non-EIPH was observed in 90 patients. The patients with EIPH had a higher mPAP at rest than those without EIPH. The probability of PH based on the DL model was significantly higher in patients with EIPH than in those without EIPH. Multivariate analysis showed that gender, mean PAP at rest, and the probability of PH based on the DL model were independent predictors of EIPH. A model based on baseline parameters (age, gender, and mPAP at rest) was improved by adding the probability of PH predicted by the DL model (AUC: from 0.65 to 0.74; p = 0.046).

Conclusion

Applying the DL model based on a CXR may have a potential for detection of EIPH in the clinical setting.

Exercise-induced pulmonary hypertension in HFpEF and HFrEF: Different pathophysiologic mechanism behind similar functional impairment

AIMS

Pathophysiological mechanisms behind cardio-pulmonary impairment in heart failure (HF) with reduced (HFrEF) and preserved (HFpEF) ejection fraction are likely different. We analysed them using combined cardiopulmonary-exercise stress echocardiography (CPET-ESE).

METHODS

We matched 1:1 subjects with HFrEF (n = 90) and HFpEF (n = 90) for age, sex, body mass index (BMI), peak oxygen consumption, and minute ventilation/carbon dioxide production slope. All patients underwent a symptom-limited graded ramp bicycle CPET-ESE compared with 40 age-, sex- and BMI-matched healthy controls.

RESULTS

During a median follow-up of 25 months, we observed 22 deaths and 80 HF hospitalisations, with similar distribution between HFpEF and HFrEF. Compared with HFrEF, HFpEF had a higher prevalence of metabolic syndrome (p = 0.02) with higher levels of high-sensitivity C-reactive protein and uric acid (p < 0.01). The multipoint mean pulmonary artery pressure/cardiac output (mPAP/CO) slope showed equally increased values in HFrEF and HFpEF (3.5 ± 1.8 and 3.7 ± 1.5 mmHg/L/min) compared with controls (1.8 ± 1.1 mmHg/L/min; p < 0.0001). During exercise, HFpEF displayed more adverse interaction of right ventricle-pulmonary artery (RV-PA; tricuspid annular plane systolic excursion/systolic pulmonary artery pressure: 0.40 ± 0.2 vs 0.47 ± 0.2 mm/mmHg in HFrEF; p < 0.01) and left atrium-left ventricle (LA-LV; LA reservoir strain/LV global longitudinal strain: 1.5 ± 0.8 vs 2.2 ± 1.1 in HFrEF; p < 0.01). The latter were independent predictors of mPAP/CO slope, along with hs-CRP (adjusted R2: 0.21; p < 0.0001).

CONCLUSION

Despite similar disease severity, HFpEF and HFrEF show different pathophysiological mechanisms. HFpEF is characterised by a worse LA-LV and RV-PA interaction than HFrEF, with more prevalent low-grade systemic inflammation. In HFpEF, these features may have a role in exercise-induced pulmonary hypertension.

Invasive Hemodynamic Evaluation of the Fontan Circulation: Current Day Practice and Limitations

PURPOSE OF REVIEW

Establishing the Fontan circulation has led to improved survival in patients born with complex congenital heart diseases. Despite early success, the long-term course of Fontan patients is complicated by multi-organ dysfunction, mainly due to a combination of low resting and blunted exercise-augmented cardiac output as well as elevated central venous (Fontan) pressure. Similarly, despite absolute hemodynamic differences compared to the normal population with biventricular circulation, the "normal" ranges of hemodynamic parameters specific to age-appropriate Fontan circulation have not been well defined. With the ever-increasing population of patients requiring Fontan correction, it is of utmost importance that an acceptable range of hemodynamics in this highly complex patient cohort is better defined.

RECENT FINDINGS

Multiple publications have described hemodynamic limitations and potential management options in patients with Fontan circulation; however, an acceptable range of hemodynamic parameters in this patient population has not been well defined. Identification of "normal" hemodynamic parameters among patients with Fontan circulation will allow physicians to more objectively define indications for intervention, which is a necessary first step to eliminate institutional and regional heterogeneity in Fontan management and potentially improve long-term clinical outcomes.

Peripheral Venous Pressure-Assisted Exercise Stress Echocardiography in the Evaluation of Pulmonary Hypertension During Exercise in Patients With Suspected Heart Failure With Preserved Ejection Fraction

BACKGROUND

Identification of elevated pulmonary artery (PA) pressures during exercise may provide diagnostic, prognostic, and therapeutic implications in heart failure with preserved ejection fraction. Although widely performed, exercise stress echocardiography may underestimate true PA pressures due to the difficulty in estimating right atrial pressure (RAP) during exercise. We hypothesized that peripheral venous pressure (PVP) could allow for reliable estimation of RAP, and thus PA pressures during exercise stress echocardiography.

METHODS

In protocol 1, we investigated the accuracy of PVP compared with simultaneously measured RAP at rest and during exercise right heart catheterization in 19 subjects. In protocol 2, we examined whether the addition of PVP to Doppler exercise echocardiography (tricuspid regurgitant velocity) would increase the ability to identify exercise-induced pulmonary hypertension compared with inferior vena cava-based RAP estimation in 60 patients with dyspnea.

RESULTS

In protocol 1, PVP was strongly correlated with simultaneously measured RAP at rest and during exercise (r=0.77 and 0.90), with little overestimation of invasively measured RAP (bias 3.4 mm Hg at rest and 1.7 mm Hg during exercise). In protocol 2, PVP increased dramatically during exercise echocardiography (14±5 mm Hg) while an increase in inferior vena cava-based RAP was modest (6±4 mm Hg). Exercise PA pressures calculated from PVP and tricuspid regurgitant velocity were significantly higher than those estimated from inferior vena cava and the use of PVP increased the proportion of patients with exercise-induced pulmonary hypertension from 40% to 68%.

CONCLUSIONS

PVP may prevent underestimation of PA pressures during exercise echocardiography and could be a preferred approach to identify exercise-induced pulmonary hypertension in patients with suspected heart failure with preserved ejection fraction.

Influence of Upright Versus Supine Position on Resting and Exercise Hemodynamics in Patients Assessed for Pulmonary Hypertension

Background

The aim of the present work was to study the influence of body position on resting and exercise pulmonary hemodynamics in patients assessed for pulmonary hypertension (PH).

Methods and Results

Data from 483 patients with suspected PH undergoing right heart catheterization for clinical indications (62% women, age 61±15 years, 246 precapillary PH, 48 postcapillary PH, 106 exercise PH, 83 no PH) were analyzed; 213 patients (main cohort, years 2016–2018) were examined at rest in upright (45°) and supine position, such as under upright exercise. Upright exercise hemodynamics were compared with 270 patients (historical cohort) undergoing supine exercise with the same protocol. Upright versus supine resting data revealed a lower mean pulmonary artery pressure 31±14 versus 32±13 mm Hg, pulmonary artery wedge pressure 11±4 versus 12±5 mm Hg, and cardiac index 2.9±0.7 versus 3.1±0.8 L/min per m 2 , and higher pulmonary vascular resistance 4.1±3.1 versus 3.9±2.8 Wood P <0.001. Exercise data upright versus supine revealed higher work rates (53±26 versus 33±22 watt), and adjusting for differences in work rate and baseline values, higher end‐exercise mean pulmonary artery pressure (52±19 versus 45±16 mm Hg, P =0.001), similar pulmonary artery wedge pressure and cardiac index, higher pulmonary vascular resistance (5.4±3.7 versus 4.5±3.4 Wood units, P =0.002), and higher mean pulmonary artery pressure/cardiac output (7.9±4.7 versus 7.1±4.1 Wood units, P =0.001).

Conclusions

Body position significantly affects resting and exercise pulmonary hemodynamics with a higher pulmonary vascular resistance of about 10% in upright versus supine position at rest and end‐exercise, and should be considered and reported when assessing PH.

Diastolic Dysfunction Is Unmasked on Exercise in Patients With Asymptomatic, Severe Aortic Stenosis: An Invasive Hemodynamic Study

BACKGROUND

Optimal timing of aortic valve replacement remains difficult in patients with asymptomatic, severe aortic stenosis (AS). More accurate diagnostic methods are warranted for the detection of subtle ventricular impairment. We aimed to evaluate diastolic function in asymptomatic patients with severe AS.

METHODS

In this cross-sectional study, patients with asymptomatic, severe AS were evaluated with right heart catheterization at rest and during moderate exercise. The patients also underwent cardiopulmonary exercise testing to objectify functional capacity and confirm the absence of symptoms.

RESULTS

Between February 2019 and May 2021, we included 50 patients aged 70±12 years. The patients had severe AS with peak velocity 4.4±0.4 m/s, mean gradient 46±9 mm Hg, and an indexed valve area of 0.47±0.08 cm² at rest. All patients were asymptomatic and had normal left ventricular ejection fraction. Five patients had postcapillary pulmonary hypertension at rest. During exercise, 44 patients (88%) had an increase in the mean pulmonary artery pressure per increase in cardiac output of >3 mm Hg/L per minute, of whom 93% had a concomitant increase in the pulmonary artery wedge pressure per increase in cardiac output >2 mm Hg/L per minute, suggesting exercise-induced pulmonary hypertension due to left heart disease. Female gender and increasing age were associated with a higher increase in the pulmonary artery wedge pressure per increase in cardiac output ratio. The catheterization was well tolerated, and there were no adverse events.

CONCLUSIONS

A large proportion of asymptomatic patients with severe, degenerative AS have exercise-induced postcapillary pulmonary hypertension.

Physiological aspects of cardiopulmonary dysanapsis on exercise in adults born preterm

Progressive improvements in perinatal care and respiratory management of preterm infants have resulted in increased survival of newborns of extremely low gestational age over the past few decades. However, the incidence of bronchopulmonary dysplasia, the chronic lung disease after preterm birth, has not changed. Studies of the long-term follow-up of adults born preterm have shown persistent abnormalities of respiratory, cardiovascular and cardiopulmonary function, possibly leading to a lower exercise capacity. The underlying causes of these abnormalities are incompletely known, but we hypothesize that dysanapsis, i.e. discordant growth and development, in the respiratory and cardiovascular systems is a central structural feature that leads to a lower exercise capacity in young adults born preterm than those born at term. We discuss how the hypothesized system dysanapsis underscores the observed respiratory, cardiovascular and cardiopulmonary limitations. Specifically, adults born preterm have: (1) normal lung volumes but smaller airways, which causes expiratory airflow limitation and abnormal respiratory mechanics but without impacts on pulmonary gas exchange efficiency; (2) normal total cardiac size but smaller cardiac chambers; and (3) in some cases, evidence of pulmonary hypertension, particularly during exercise, suggesting a reduced pulmonary vascular capacity despite reduced cardiac output. We speculate that these underlying developmental abnormalities may accelerate the normal age-associated decline in exercise capacity, via an accelerated decline in respiratory, cardiovascular and cardiopulmonary function. Finally, we suggest areas of future research, especially the need for longitudinal and interventional studies from infancy into adulthood to better understand how preterm birth alters exercise capacity across the lifespan.

The definition of pulmonary hypertension: history, practical implications and current controversies

The definition of pulmonary hypertension (PH) is based on a growing body of evidence and represents the result of ongoing discussions within the PH community over the past 50 years. In 2018, the most recent World Symposium on Pulmonary Hypertension introduced significant changes in the definition of PH by lowering the mean pulmonary arterial pressure threshold to >20 mmHg and (re)introducing the pulmonary vascular resistance ≥3 WU cut-off for all forms of pre-capillary PH. These changes and their potential clinical impact have been the subject of lively discussions in the community and some important questions and controversies have been identified.

In this review we aim to present the development of the definition of PH over the past decades and discuss the main arguments that led to relevant modifications. In addition, we address the practical implications of the most recent changes and controversies that still exist.

The definitions of PH and PAH reflect the upper limit of normal haemodynamic values, their prognostic relevance and practical considerations. With appropriate clinical context they represent the cornerstone of PH diagnosis and clinical decision making.https://bit.ly/3gRSyWz

Ratio of Mixed Venous Oxygen Saturation-to-Pulmonary Capillary Wedge Pressure: Insights From the Veterans Affairs Clinical Assessment, Reporting, and Tracking Program

BACKGROUND

Hemodynamic values from right heart catheterization aid diagnosis and clinical decision-making but may not predict outcomes. Mixed venous oxygen saturation percentage and pulmonary capillary wedge pressure relate to cardiac output and congestion, respectively. We theorized that a novel, simple ratio of these measurements could estimate cardiovascular prognosis.

METHODS

We queried Veterans Affairs' databases for clinical, hemodynamic, and outcome data. Using the index right heart catheterization between 2010 and 2016, we calculated the ratio of mixed venous oxygen saturation-to-pulmonary capillary wedge pressure, termed ratio of saturation-to-wedge (RSW). The primary outcome was time to all-cause mortality; secondary outcome was 1-year urgent heart failure presentation. Patients were stratified into quartiles of RSW, Fick cardiac index (CI), thermodilution CI, and pulmonary capillary wedge pressure alone. Kaplan-Meier curves and Cox proportional hazards models related comparators with outcomes.

RESULTS

Of 12 019 patients meeting inclusion criteria, 9826 had values to calculate RSW (median 4.00, interquartile range, 2.67-6.05). Kaplan-Meier curves showed early, sustained separation by RSW strata. Cox modeling estimated that increasing RSW by 50% decreases mortality hazard by 19% (estimated hazard ratio, 0.81 [95% CI, 0.79-0.83], P<0.001) and secondary outcome hazard by 28% (hazard ratio, 0.72 [95% CI, 0.70-0.74], P<0.001). Among the 3793 patients with data for all comparators, Cox models showed RSW best associated with outcomes (by both C statistics and Bayes factors). Furthermore, pulmonary capillary wedge pressure was superior to thermodilution CI and Fick CI. Multivariable adjustment attenuated without eliminating the association of RSW with outcomes.

CONCLUSIONS

In a large national database, RSW was superior to conventional right heart catheterization indices at assessing risk of mortality and urgent heart failure presentation. This simple calculation with routine data may contribute to clinical decision-making in this population.

Hemodynamics for the Heart Failure Clinician: A State-of-the-Art Review

Heart failure (HF) fundamentally reflects an inability of the heart to provide adequate blood flow to the body without incurring the cost of increased cardiac filling pressures. This failure occurs first during the stressed state, but progresses until hemodynamic derangements become apparent at rest. As such, the measurement and interpretation of both resting and stressed hemodynamics serve an integral role in the practice of the HF clinician. In this review, we discuss conceptual and technical best practices in the performance and interpretation of both resting and invasive exercise hemodynamic catheterization, relate important pathophysiologic concepts to clinical care, and discuss updated, evidence-based applications of hemodynamics as they pertain to the full spectrum of HF conditions.

Comparison of Repetitive Cardiac Output Measurements at Rest and End-Exercise by Direct Fick Using Pulse Oximetry vs. Blood Gases in Patients With Pulmonary Hypertension

Background: Exact and simultaneous measurements of mean pulmonary artery pressure (mPAP) and cardiac output (CO) are crucial to calculate pulmonary vascular resistance (PVR), which is essential to define pulmonary hypertension (PH). Simultaneous measurements of mPAP and CO are not feasible using the direct Fick (DF) method, due to the necessity to sample blood from the catheter-tip. We evaluated a modified DF method, which allows simultaneous measurement of mPAP and CO without needing repetitive blood samples.

Methods: Twenty-four patients with pulmonary arterial or chronic thromboembolic PH had repetitive measurements of CO at rest and end-exercise during three phases of a crossover trial. CO was assessed by the original DF method using oxygen uptake, measured by a metabolic unit, and arterial and mixed venous oxygen saturations from co-oximetry of respective blood gases served as reference. These CO measurements were then compared with a modified DF method using pulse oximetry at the catheter- and fingertip.

Results: The bias among CO measurements by the two DF methods at rest was −0.26 L/min with limits of agreement of ±1.66 L/min. The percentage error was 28.6%. At the end-exercise, the bias between methods was 0.29 L/min with limits of agreement of ±1.54 L/min and percentage error of 16.1%.

Conclusion: Direct Fick using a catheter- and fingertip pulse oximetry (DFp) is a practicable and reliable method for assessing CO in patients with PH. This method has the advantage of allowing simultaneous measurement of PAP and CO, and frequent repetitive measurements are needed during exercise.

Clinical Trial Registration:https://clinicaltrials.gov/ct2/show/NCT02755259, identifier: NCT02755259.

[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.

Pulmonary Hypertension Associated with Connective Tissue Disease

Pulmonary hypertension (PH), a syndrome characterized by elevated pulmonary pressures, commonly complicates connective tissue disease (CTD) and is associated with increased morbidity and mortality. The incidence of PH varies widely between CTDs; patients with systemic sclerosis are most likely to develop PH. Several different types of PH can present in CTD, including PH related to left heart disease and respiratory disease. Importantly, CTD patients are at risk for developing pulmonary arterial hypertension, a rare form of PH that is associated with high morbidity and mortality. Future therapies targeting pulmonary vascular remodeling may improve outcomes for patients with this devastating disease.

Pathophysiological and diagnostic importance of fatty acid-binding protein 1 in heart failure with preserved ejection fraction

Elevated intracardiac pressure at rest and/or exercise is a fundamental abnormality in heart failure with preserved ejection fraction (HFpEF). Fatty acid-binding protein 1 (FABP1) is proposed to be a sensitive biomarker for liver injury. We sought to determine whether FABP1 at rest would be elevated in HFpEF and would correlate with echocardiographic markers of intracardiac pressures at rest and during exercise. In this prospective study, subjects with HFpEF (n = 22) and control subjects without HF (n = 23) underwent resting FABP1 measurements and supine bicycle exercise echocardiography. Although levels of conventional hepatic enzymes were similar between groups, FABP1 levels were elevated in HFpEF compared to controls (45 [25–68] vs. 18 [14–24] ng/mL, p = 0.0008). FABP1 levels were correlated with radiographic and blood-based markers of congestion, hemodynamic derangements during peak exercise (E/e’, r = 0.50; right atrial pressure, r = 0.35; pulmonary artery systolic pressure, r = 0.46), reduced exercise cardiac output (r = − 0.49), and poor exercise workload achieved (r = − 0.40, all p < 0.05). FABP1 distinguished HFpEF from controls with an area under the curve of 0.79 (p = 0.003) and had an incremental diagnostic value over the H₂FPEF score (p = 0.007). In conclusion, FABP1 could be a novel hepatic biomarker that associates with hemodynamic derangements, reduced cardiac output, and poor exercise capacity in HFpEF.

Pulmonary hypertension phenotypes in patients with systemic sclerosis

Pulmonary hypertension (PH) commonly affects patients with systemic sclerosis (SSc) and is associated with significant morbidity and increased mortality. PH is a heterogenous condition and several different forms can be associated with SSc, including pulmonary arterial hypertension (PAH) resulting from a pulmonary arterial vasculopathy, PH due to left heart disease and PH due to interstitial lung disease. The incidence of pulmonary veno-occlusive disease is also increased. Accurate and early diagnosis to allow optimal treatment is, therefore, essential. Recent changes to diagnostic haemodynamic criteria at the 6th World Symposium on Pulmonary Hypertension have resulted in therapeutic uncertainty regarding patients with borderline pulmonary haemodynamics. Furthermore, the optimal pulmonary vascular resistance threshold for diagnosing PAH and the role of exercise in identifying early disease require further elucidation. In this article we review the epidemiology, diagnosis, outcomes and treatment of the spectrum of pulmonary vascular phenotypes associated with SSc.

Right ventricular and cyclic guanosine monophosphate signalling abnormalities in stages B and C of heart failure with preserved ejection fraction

Aims

Identifying early right ventricular (RV) dysfunction and impaired vasodilator reserve is challenging in heart failure with preserved ejection fraction (HFpEF). We hypothesized that cardiac magnetic resonance (CMR)‐based exercise imaging and serial cyclic guanosine monophosphate (cGMP) measurements can identify dynamic RV‐arterial uncoupling and responsiveness to pulmonary vasodilators at early stages of the HFpEF syndrome.

Methods and results

Patients with HFpEF (n = 16), impaired left ventricular relaxation due to concentric remodelling (LVCR, n = 7), and healthy controls (n = 8) underwent CMR at rest and during supine bicycle exercise with simultaneous measurements of central haemodynamics and circulating cGMP levels, before and after oral administration of 50 mg sildenafil. At rest, mean pulmonary artery pressures (mPAP) were higher in HFpEF, compared with LVCR and controls (27 ± 2, 18 ± 1, and 11 ± 1, respectively; P = 0.01), whereas biventricular volumes, heart rate, and stroke volume were similar. During exercise, LVCR and HFpEF had a greater increase in the ratio of mPAP over cardiac output than controls (5.50 ± 0.77 and 6.34 ± 0.86 vs. 2.24 ± 0.55 in controls, P = 0.005). The ratio of peak exercise to rest RV end‐systolic pressure‐volume, a surrogate of RV contractility, was significantly reduced in LVCR and HFpEF (2.32 ± 0.17 and 1.56 ± 0.08 vs. 3.49 ± 0.35 in controls, P < 0.001) and correlated with peak exercise VO₂ (R² = 0.648, P < 0.001). cGMP levels increased with exercise across the HFpEF spectrum (P < 0.05 vs. baseline), except when postcapillary pulmonary hypertension was present at rest (P = 0.73 vs. baseline). A single sildenafil administration failed to increase circulating cGMP levels and did not improve RV performance.

Conclusion

Exercise CMR identifies impaired RV‐arterial coupling at an early stage of HFpEF. Circulating cGMP levels phenocopy the haemodynamic spectrum in HFpEF but fail to increase after phosphodiesterase type 5 inhibition, endorsing the need for alternative interventions to increase cGMP signalling in HFpEF.

Under Pressure: Right Heart Catheterization and Provocative Testing for Diagnosing Pulmonary Hypertension

Pulmonary hypertension (PH) is a heterogenous disorder involving multiple pathophysiological processes that ultimately affect the vasculature within the lungs. Right heart catheterization (RHC) continues to be the benchmark for diagnosing PH. The use of provocation techniques during RHC can help sub-characterize the type of PH and thus assist in developing appropriate treatment strategies for the management of each PH subtype. This review examines proven and novel approaches for evaluating the pulmonary vasculature during RHC and aspires to provide an accurate, clinically relevant framework for using RHC to diagnose and manage PH. Further improvement in standardized protocols will help optimize the application of RHC in patients with PH.

Exercise intolerance in pulmonary arterial hypertension: insight into central and peripheral pathophysiological mechanisms

Exercise intolerance is a cardinal symptom of pulmonary arterial hypertension (PAH) and strongly impacts patients' quality of life (QoL). Although central cardiopulmonary impairments limit peak oxygen consumption (V' O2peak ) in patients with PAH, several peripheral abnormalities have been described over the recent decade as key determinants in exercise intolerance, including impaired skeletal muscle (SKM) morphology, convective O2 transport, capillarity and metabolism indicating that peripheral abnormalities play a greater role in limiting exercise capacity than previously thought. More recently, cerebrovascular alterations potentially contributing to exercise intolerance in patients with PAH were also documented. Currently, only cardiopulmonary rehabilitation has been shown to efficiently improve the peripheral components of exercise intolerance in patients with PAH. However, more extensive studies are needed to identify targeted interventions that would ultimately improve patients' exercise tolerance and QoL. The present review offers a broad and comprehensive analysis of the present literature about the complex mechanisms and their interactions limiting exercise in patients and suggests several gaps in knowledge that need to be addressed in the future for a better understanding of exercise intolerance in patients with PAH.

Association between lung ultrasound B-lines and exercise-induced pulmonary hypertension in patients with connective tissue disease

BACKGROUND

Identification of elevation in pulmonary pressures during exercise may provide prognostic and therapeutic implications in patients with connective tissue disease (CTD). Interstitial lung disease (ILD) is common in CTD patients and subtle interstitial abnormalities detected by lung ultrasound could predict exercise-induced pulmonary hypertension (PH).

METHODS AND RESULTS

Echocardiography and lung ultrasound were performed at rest and bicycle exercise in CTD patients (n = 41) and control subjects without CTD (n = 24). Ultrasound B-lines were quantified by scanning four intercostal spaces in the right hemithorax. We examined the association between total B-lines at rest and the development of exercise-induced PH during ergometry exercise. Compared to controls, the number of total B-lines at rest was higher in CTD patients (0 [0, 0] vs 2 [0, 9], P < .0001) and was correlated with radiological severity of ILD assessed by computed tomography (fibrosis score, r = .70, P < .0001). Pulmonary artery systolic pressure (PASP) was increased with ergometry exercise in CTD compared to controls (48 ± 14 vs 35 ± 13 mm Hg, P = .0006). The number of total B-lines at rest was highly correlated with higher PASP (r = .52, P < .0001) and poor right ventricular pulmonary artery coupling (tricuspid annular plane systolic excursion/PASP ratio, r = -.31, P = .01) during peak exercise. The number of resting B-lines predicted the development of exercise-induced PH with an area under the curve .79 (P = .0003).

CONCLUSIONS

These data may suggest the value of a simple resting assessment of lung ultrasound as a potential tool for assessing the risk of exercise-induced PH in CTD patients.

High Right Ventricular Afterload during Exercise in Patients with Pulmonary Arterial Hypertension

The right ventricle (RV) is more sensitive to an increase in afterload than the left ventricle (LV), and RV afterload during exercise increases more easily than LV afterload. Pulmonary arterial hypertension (PAH)-specific therapy has improved pulmonary hemodynamics at rest; however, the pulmonary hemodynamic response to exercise is still abnormal in most patients with PAH. In these patients, RV afterload during exercise could be higher, resulting in a greater increase in RV wall stress. Recently, an increasing number of studies have indicated the short-term efficacy of exercise training. However, considering the potential risk of promoting myocardial maladaptive remodeling, even low-intensity repetitive exercise training could lead to long-term clinical deterioration. Further studies investigating the long-term effects on the RV and pulmonary vasculature are warranted. Although the indications for exercise training for patients with PAH have been expanding, exercise training may be associated with various risks. Training programs along with risk stratification based on the pulmonary hemodynamic response to exercise may enhance the safety of patients with PAH.

Current Limitations of Invasive Exercise Hemodynamics for the Diagnosis of Heart Failure With Preserved Ejection Fraction

BACKGROUND

Exercise hemodynamics can differentiate heart failure with preserved ejection fraction (HFpEF) from noncardiac dyspnea. However, respiratory pressure swings may impact hemodynamic measurements, potentially leading to misdiagnosis of HFpEF. Moreover, threshold values for abnormal hemodynamic response indicative of HFpEF are not universally accepted. Thus, we sought to evaluate the impact of respiratory pressure swings on hemodynamic data interpretation as well as the concordance among 3 proposed exercise hemodynamic criteria for HFpEF: (1) end-expiratory pulmonary artery wedge pressure (PAWP_exp) ≥25 mm Hg; (2) PAWP_exp/cardiac output slope >2 mm Hg/L per minute; and (3) respiratory-averaged (avg) mean pulmonary artery pressure >30 mm Hg, total pulmonary resistance_avg >3 WU, PAWP_avg ≥20 mm Hg.

METHODS

Fifty-seven patients with unexplained dyspnea (70% women, 70±9 years) underwent exercise cardiac catheterization. The difference between end-expiratory and averaged hemodynamic values, as well as the concordance among the 3 hemodynamic definitions of HFpEF, were assessed.

RESULTS

End-expiratory hemodynamics measurements were higher than values averaged across the respiratory cycle. During exercise, a larger proportion of patients exceeded the threshold of 25 mm Hg for PAWP_exp rather than for PAWP_avg (70% versus 53%, P<0.01). The concordance of 3/3 HFpEF exercise hemodynamic criteria was recorded in 70% of patients. PAWP_exp/cardiac output slope identified HFpEF more frequently than the other 2 criteria (81% versus 64% to 69%), incorporating over 97% of abnormal responses to the latter. Patients with 3/3 positive criteria had worse clinical, gas-exchange, and hemodynamic profiles.

CONCLUSIONS

Respiratory pressure swings impact on the exercise hemodynamic definitions of HFpEF that provide discordant results in 30% of patients. Equivocal diagnoses of HFpEF might be limited by adopting the most sensitive and inclusive criterion alone (ie, PAWP_exp/cardiac output slope).