Characteristics of patients with pulmonary venoocclusive disease awaiting transplantation

Pulmonary Hypertension in Systemic Sclerosis

Systemic sclerosis is a multisystem connective tissue disease that is associated with substantial morbidity and mortality. Visceral organ involvement is common in patients with systemic sclerosis and occurs independently of skin manifestations. Pulmonary hypertension (PH) is an important and prevalent complication of systemic sclerosis. The clinical classification of PH cohorts conditions with similar pathophysiological mechanisms into one of five groups. While patients with systemic sclerosis can manifest with a spectrum of pulmonary vascular disease, notable clinical groups include group 1 pulmonary arterial hypertension (PAH) associated with connective tissues disease, PAH with features of capillary/venous involvement, group 2 PH associated with left heart disease, and group 3 PH associated with interstitial lung disease. Considerable efforts have been made to advance screening methods for PH in systemic sclerosis including the DETECT and ASIG (Australian Scleroderma Interest Group) composite algorithms. Current guidelines recommend annual assessment of the risk of PAH as early recognition may result in attenuated hemodynamic impairment and improved survival. The treatment of PAH associated with systemic sclerosis requires a multidisciplinary team including a PH specialist and a rheumatologist to optimize immunomodulatory and PAH-specific therapies. Several potential biomarkers have been identified and there are several promising PAH therapies on the horizon such as the novel fusion protein sotatercept. This chapter provides an overview of PH in systemic sclerosis, with a specific focus on group 1 PAH.

Pulmonary Arterial Hypertension with Features of Venous Involvement: A Detective's Task

Pulmonary veno-occlusive disease (PVOD) and pulmonary capillary hemangiomatosis are rare types of histopathological substrates within the spectrum of pulmonary arterial hypertension (PAH) with a very poor prognosis. They are characterized by a widespread fibroproliferative process of the small caliber veins and/or capillaries with sparing of the larger veins, resulting in a pre-capillary pulmonary hypertension phenotype. Clinical presentation is unspecific and similar to other PAH etiologies. Definitive diagnosis is obtained through histological analysis, although lung biopsy is not advised due to a higher risk of complications. However, some additional findings may allow a presumptive clinical diagnosis of PVOD, particularly a history of smoking, chemotherapy drug use, exposure to organic solvents (particularly trichloroethylene), low diffusing capacity for carbon monoxide (DLCO), exercise induced desaturation, and evidence of venous congestion without left heart disease on imaging, manifested by a classical triad of ground glass opacities, septal lines, and lymphadenopathies. Lung transplant is the only effective treatment, and patients should be referred at the time of diagnosis due to the rapid progression of the disease and associated poor prognosis. We present a case of a 58-year-old man with PAH with features of venous/capillary involvement in which clinical suspicion, prompt diagnosis, and early referral for lung transplantation were determinant factors for the successful outcome.

Lung Transplantation for Pulmonary Arterial Hypertension: Optimized Referral and Listing Based on an Evolving Disease Concept

Pulmonary hypertension (PH) was once a devastating and fatal disease entity, the outlook of which has been significantly improved by the continued progress of medical treatment algorithms. However, some patients still ultimately fail to achieve an adequate clinical response despite receiving maximal medical treatment. Historically, lung transplantation (LTx) has been the only effective therapeutic option that could lead to satisfactory outcomes and save these advanced patients' lives. However, patients with PH tend to have the highest mortality rates on the transplant waiting list; especially after comprehensive medical treatment, they continue to deteriorate very rapidly, eventually missing optimal transplantation windows. Balancing optimized medical treatment with the appropriate timing of referral and listing has been highly controversial in LTx for patients with PH. The 2021 consensus document for the selection of lung transplant candidates from the International Society for Heart and Lung Transplantation (ISHLT) updated the specific recommendations for the LTx referral and listing time for patients with PH based on objective risk stratification. Herein, we review the evolving PH-related concepts and highlight the optimization of LTx referral and listing for patients with PH, as well as their management on the waiting list.

Diagnosis and management of pulmonary veno-occlusive disease

INTRODUCTION

Pulmonary veno-occlusive disease (PVOD) is an orphan disease and uncommon etiology of pulmonary arterial hypertension (PAH) characterized by substantial small pulmonary vein and capillary involvement.

AREAS COVERED

PVOD, also known as 'PAH with features of venous/capillary involvement' in the current ESC/ERS classification.

EXPERT OPINION

In recent years, particular risk factors for PVOD have been recognized, including genetic susceptibilities and environmental factors (such as exposure to occupational organic solvents, chemotherapy, and potentially tobacco). The discovery of biallelic mutations in the EIF2AK4 gene as the cause of heritable PVOD has been a breakthrough in understanding the molecular basis of PVOD. Venous and capillary involvement (PVOD-like) has also been reported to be relatively common in connective tissue disease-associated PAH (especially systemic sclerosis), and in rare pulmonary diseases like sarcoidosis and pulmonary Langerhans cell granulomatosis. Although PVOD and pulmonary arterial hypertension (PAH) exhibit similarities, including severe precapillary PH, it is essential to differentiate between them since PVOD has a worse prognosis and requires specific management. Indeed, PVOD patients are characterized by poor response to PAH-approved drugs, which can lead to pulmonary edema and clinical deterioration. Due to the lack of effective treatments, early referral to a lung transplantation center is crucial.

Lung transplantation for pulmonary hypertension

From its identification as a distinct disease entity, understanding and management of pulmonary hypertension has continuously evolved. Diagnostic and therapeutic interventions have greatly improved the prognostic implications of this devastating disease, previously rapidly and uniformly fatal to one chronically managed by multi-disciplinary teams. Improved diagnostic algorithms and active research into biochemical signatures of pulmonary hypertension (PH) have led to earlier diagnosis of PH. Medical therapy has moved from upfront use of continuous intravenous prostaglandins to administration of combinations of oral medications targeting multiple pathways underlying this disease process. In addition to improved medical therapies, recently introduced interventions such as pulmonary endarterectomy and pulmonary artery balloon angioplasty for chronic thromboembolic pulmonary hypertension (CTEPH) give patients an increasing array of treatment options. Despite these many advances, lung transplantation remains the definitive treatment for patients with disease refractory to or progressing on best medical therapy. As our understanding of medical therapy has advanced, so to have best practices for lung transplantation. Recipient selection and approach to organ transplantation techniques have continuously evolved. Mechanical circulatory support has become increasingly employed to bridge patients through lung transplantation in the immediate post transplantation recovery. In this review, we give a history of lung transplantation for PH, an overview of PH, discuss current best practices and look to the future for insights into the care of these patients.

Pulmonary veno-occlusive disease in childhood-a rare disease not to be missed

Pulmonary veno-occlusive disease (PVOD) is a rare disease leading to pulmonary hypertension and potentially death related to right heart failure and/or respiratory insufficiency. Clinical symptoms are heterogenous and nonspecific: fatigue, decreased exercise tolerance, shortness of breath on exertion, cough, dizziness, chest pain with exercise, palpitations, syncope, as well as nonspecific symptoms such as headache, poor appetite, pallor or perioral cyanosis. Mutations in the EIF2AK4 (eukaryotic translation initiation factor 2-alpha kinase 4) have been recently described, other risk factors include exposure to organic solvent and trichloroethylene, tobacco exposure and chemotherapy. Echocardiography helps to estimate right ventricular systemic pressure, but further diagnostic workup includes cardiac catheterization to confirm pulmonary hypertension and increased pulmonary vascular resistance. High-resolution computed tomography reveals typical findings: centrilobular ground-glass nodules or opacities, septal lines, thickened interlobular septa, mosaic perfusion, and lymphadenopathy. Histology remains the gold standard, but carries risks for the patient. Proper workup is essential in order to avoid incorrect diagnosis. Pulmonary hypertension targeted treatment has been used in patients with PVOD, however, experience is limited, vasodilatory effects on pulmonary vasculature may lead to deterioration of the patients and should be used with great caution. Lung transplantation is currently the only valid treatment option for patients with PVOD. With prolonged waiting time and progression of the disease mechanical support could be considered.

Anti-synthetase syndrome-associated pulmonary veno-occlusive disease

Pulmonary arterial hypertension has been reported with a prevalence of 7.9% in patients with anti-synthetase syndrome; however, anti-synthetase syndrome associated with pulmonary veno-occlusive disease (PVOD) has never before been described in the literature. We present a novel case of anti-synthetase syndrome-associated PVOD in a patient who presented with hypoxic respiratory failure associated with right heart failure and was diagnosed with anti-synthetase syndrome based on his autoimmune serology and pre-capillary pulmonary hypertension on right heart catheterization. He was initiated on pulmonary arterial hypertension therapy, but with escalating dose of parenteral epoprostenol, experienced acute clinical worsening with chest imaging concerning for PVOD that was confirmed on autopsy. Anti-synthetase syndrome can be associated with PVOD, and it should be suspected in patients who have evidence of pre-capillary pulmonary hypertension and who deteriorate with the initiation of pulmonary hypertension-specific therapy.

Computed tomographic and clinical features of pulmonary veno-occlusive disease: raising the radiologist's awareness

Pulmonary veno-occlusive disease (PVOD) is a rare subtype of pulmonary arterial hypertension (PAH) characterised by preferential remodelling of the pulmonary venules. Differentiation from other subtypes of PAH is essential as the management can differ significantly; for example, initiation of vasodilator therapy may cause fatal pulmonary oedema in a patient with PVOD misdiagnosed with idiopathic PAH. PVOD also carries a substantially worse prognosis. Lung biopsy is required for definitive diagnosis, but this is hazardous, and ideally, should be avoided in pulmonary hypertension. Computed tomography (CT) may suggest the diagnosis, directing the patient towards specialist review. Potential distinguishing CT features between PVOD and other subtypes of PAH include interlobular septal thickening, mediastinal lymphadenopathy, and centrilobular ground-glass opacities. No evidence-based medical therapy exists for PVOD at present and lung transplantation remains the definitive treatment for eligible patients. Therefore, early radiological identification of this challenging diagnosis facilitates timely referral for transplant.

Beneficial Effects of Imatinib in a Patient with Suspected Pulmonary Veno-Occlusive Disease

Pulmonary veno-occlusive disease (PVOD) is a rare form of pulmonary hypertension (PH). The prognosis of PVOD patients remains poor, since no effective medical therapy is yet available. Imatinib is a tyrosine kinase inhibitor specific for platelet-derived growth factor receptor and is expected as a treatment option for pulmonary arterial hypertension (PAH). Recently, it has been reported that imatinib improved functional capacity of a patient with PVOD. We here report a patient with suspected PVOD who has been successfully treated with imatinib and is alive for 6 years after diagnosis. A 57-year-old woman was admitted to a hospital for severe dyspnea. Echocardiography suggested the presence of PH, because tricuspid regurgitation pressure gradient was elevated. The patient was then transferred to our hospital by an ambulance ahead of schedule due to fever and worsening dyspnea. Because the patient had no left heart disease, we diagnosed that she had PAH associated with severe right heart failure. We immediately started treatment with nitric oxide (NO) for her severe hypoxia; however, it caused pulmonary edema. We suspected PVOD from CT characteristics and pulmonary edema after PAH-targeted vasodilator therapy, and then started oral imatinib treatment. In response to imatinib, her pulmonary edema gradually improved. Since then, the patient has been alive for 6 years with imatinib and pulmonary vasodilators. At present, lung transplantation is the only effective therapy for PVOD with limited availability. We therefore propose that imatinib may be a treatment option for PVOD and a bridge to lung transplantation.

Pulmonary veno-occlusive disease: An important consideration in patients with pulmonary hypertension

Pulmonary veno-occlusive disease is a rare subcategory of pulmonary arterial hypertension (WHO Group 1). The disease is poorly understood and difficult to diagnose; it has no definitive cure to date. These patients present with nonspecific symptoms, including dyspnea, exercise intolerance, and weakness. Chest x-rays sometimes differ from idiopathic pulmonary arterial hypertension and may demonstrate alveolar infiltrates and pleural effusions. High resolution computed tomography scans reveal ground glass opacities, interlobular septal thickening, and lymphadenopathy. Echocardiography can estimate the level of pulmonary artery pressures; right heart catheterization is needed for complete hemodynamic characterization of these patients. Lung biopsies demonstrate remodeling of the venules and small veins with intimal and adventitial fibrosis. This can result in total venous occlusion and subsequent recanalization. Similar changes occur in the small arteries and arterioles but are less pronounced than the venous changes. There is no effective medical therapy for these patients, and treatment with the pulmonary arterial hypertension specific medications often causes acute deterioration with pulmonary edema. The recent discovery of the biallelic mutations of the EIF2AK4 gene as an etiology for heritable form of pulmonary veno-occlusive disease increases our understanding of the disease pathogenesis and potentially identifies a future approach to treatment. Without definitive treatment, the prognosis is very poor, and the life expectancy of these patients is much shorter than patients with pulmonary arterial hypertension. These patients need early referral to transplantation centers.

Phenotypic Characterization of EIF2AK4 Mutation Carriers in a Large Cohort of Patients Diagnosed Clinically With Pulmonary Arterial Hypertension

BACKGROUND

Pulmonary arterial hypertension (PAH) is a rare disease with an emerging genetic basis. Heterozygous mutations in the gene encoding the bone morphogenetic protein receptor type 2 (BMPR2) are the commonest genetic cause of PAH, whereas biallelic mutations in the eukaryotic translation initiation factor 2 alpha kinase 4 gene (EIF2AK4) are described in pulmonary veno-occlusive disease/pulmonary capillary hemangiomatosis. Here, we determine the frequency of these mutations and define the genotype-phenotype characteristics in a large cohort of patients diagnosed clinically with PAH.

METHODS

Whole-genome sequencing was performed on DNA from patients with idiopathic and heritable PAH and with pulmonary veno-occlusive disease/pulmonary capillary hemangiomatosis recruited to the National Institute of Health Research BioResource-Rare Diseases study. Heterozygous variants in BMPR2 and biallelic EIF2AK4 variants with a minor allele frequency of <1:10 000 in control data sets and predicted to be deleterious (by combined annotation-dependent depletion, PolyPhen-2, and sorting intolerant from tolerant predictions) were identified as potentially causal. Phenotype data from the time of diagnosis were also captured.

RESULTS

Eight hundred sixty-four patients with idiopathic or heritable PAH and 16 with pulmonary veno-occlusive disease/pulmonary capillary hemangiomatosis were recruited. Mutations in BMPR2 were identified in 130 patients (14.8%). Biallelic mutations in EIF2AK4 were identified in 5 patients with a clinical diagnosis of pulmonary veno-occlusive disease/pulmonary capillary hemangiomatosis. Furthermore, 9 patients with a clinical diagnosis of PAH carried biallelic EIF2AK4 mutations. These patients had a reduced transfer coefficient for carbon monoxide (Kco; 33% [interquartile range, 30%-35%] predicted) and younger age at diagnosis (29 years; interquartile range, 23-38 years) and more interlobular septal thickening and mediastinal lymphadenopathy on computed tomography of the chest compared with patients with PAH without EIF2AK4 mutations. However, radiological assessment alone could not accurately identify biallelic EIF2AK4 mutation carriers. Patients with PAH with biallelic EIF2AK4 mutations had a shorter survival.

CONCLUSIONS

Biallelic EIF2AK4 mutations are found in patients classified clinically as having idiopathic and heritable PAH. These patients cannot be identified reliably by computed tomography, but a low Kco and a young age at diagnosis suggests the underlying molecular diagnosis. Genetic testing can identify these misclassified patients, allowing appropriate management and early referral for lung transplantation.

Efficacy and safety of long-term imatinib therapy for patients with pulmonary veno-occlusive disease and pulmonary capillary hemangiomatosis

BACKGROUND

Pulmonary veno-occlusive disease (PVOD) and pulmonary capillary hemangiomatosis (PCH) are categorized as Group 1' in the clinical classification of pulmonary hypertension. No medical therapy has been proven to be effective in patients with PVOD/PCH. Imatinib is a molecular targeted drug and was expected to be effective in patients with pulmonary arterial hypertension. We evaluated its efficacy and safety in patients with PVOD/PCH.

METHODS

In the present observational study, 9 patients with PVOD/PCH received imatinib. Clinical data including exercise capacity and hemodynamics at baseline and at follow-up were compared. Survival rate of patients treated with imatinib was compared to those of 7 patients who did not treated with imatinib.

RESULTS

Imatinib was prescribed at doses of 100-400 mg/day and was well-tolerated. At follow-up, World Health Organization functional class and brain natriuretic peptide levels significantly improved. Mean pulmonary arterial pressure was significantly reduced (from 56.8 ± 8.3 to 43.7 ± 9.0 mmHg) with preserved cardiac index. Patients were treated with imatinib for 797.2 ± 487.0 days. Seven patients (77.8%) died and 2 patients (22.2%) underwent lung transplantation. Mean survival time in patients treated with imatinib therapy was 1493.7 ± 196.3 days (95% confidence interval, 1108.9-1878.5 days), significantly longer than those without imatinib treatment (713.0 ± 258.1 days, log-rank test, P = 0.04).

CONCLUSIONS

Imatinib improved exercise capacity, hemodynamics and survival in patients with PVOD/PCH. In patients with PVOD/PCH, who have no effective medical therapy available, imatinib might function as a bridge to lung transplantation, and may become a potential therapeutic option to improve their survival.

Variable Expressivity of a Founder Mutation in the EIF2AK4 Gene in Hereditary Pulmonary Veno-occlusive Disease and Its Impact on Survival

INTRODUCTION AND OBJECTIVES

Hereditary pulmonary veno-occlusive disease (PVOD) has been associated with biallelic mutations in EIF2AK4 with the recent discovery of a founder mutation in Iberian Romani patients with familial PVOD. The aims of this study were phenotypical characterization and survival analysis of Iberian Romani patients with familial PVOD carrying the founder p.Pro1115Leu mutation in EIF2AK4, according to their tolerance to pulmonary vasodilators (PVD). Familial genetic screening was conducted, as well as assessment of sociocultural determinants with a potential influence on disease course.

METHODS

Observational study of Romani patients with familial PVOD included in the Spanish Registry of Pulmonary Arterial Hypertension. Genetic screening of EIF2AK4 was performed in index cases and relatives between November 2011 and July 2016 and histological pulmonary examination was carried out in patients who received a lung transplant or died. The patients were divided into 2 groups depending on their tolerance to PVD, with comparison of baseline characteristics and survival free of death or lung transplant.

RESULTS

Eighteen Romani patients were included: 9 index cases and 9 relatives. The biallelic founder mutation in EIF2AK4 was found in all affected cases and 2 unaffected relatives. Family screening showed 34.2% of healthy heterozygotes, high consanguinity, young age at childbirth, and frequent multiparity. Prognosis was bleak, with significant differences depending on tolerance to PVD.

CONCLUSIONS

We describe 2 phenotypes of hereditary PVOD depending on tolerance to PVD, with prognostic impact and familial distribution. Consanguinity may have a negative impact on the transmission of PVOD, with familial genetic screening showing high effectiveness.

Pulmonary veno-occlusive disease and pulmonary capillary hemangiomatosis

Pulmonary veno-occlusive disease is a rare cause of pulmonary hypertension which is part, together with pulmonary capillary hemangiomatosis, of the special designation (subgroup 1') within pulmonary hypertension group 1 in the latest classification of the pulmonary hypertension World Symposium. Recent discovery that gene mutations in eukaryotic translation initiation factor 2 alpha kinase 4 (EIF2AK4) are responsible for inherited forms of pulmonary veno-occlusive disease has changed the role of genetic testing, acquiring relevant importance in the diagnosis of these patients. Despite the advances in genetic, cellular and molecular basis knowledge in the last decade, pulmonary veno-occlusive disease remains as a rare aetiology of pulmonary hypertension without any effective medical treatment approved and poor outcomes. This document aims to review the advances occurred in the understanding of pulmonary veno-occlusive disease in the last years.

Clinical phenotypes and outcomes of heritable and sporadic pulmonary veno-occlusive disease: a population-based study

BACKGROUND

Bi-allelic mutations of the EIF2AK4 gene cause heritable pulmonary veno-occlusive disease and/or pulmonary capillary haemangiomatosis (PVOD/PCH). We aimed to assess the effect of EIF2AK4 mutations on the clinical phenotypes and outcomes of PVOD/PCH.

METHODS

We did a population-based study using clinical, functional, and haemodynamic data from the registry of the French Pulmonary Hypertension Network. We reviewed the clinical data and outcomes from all patients referred to the French Referral Centre (Pulmonary Department, Hospital Kremlin-Bicêtre, University Paris-Sud) with either confirmed or highly probable PVOD/PCH with DNA available for mutation screening (excluding patients with other risk factors of pulmonary hypertension, such as chronic respiratory diseases). We sequenced the coding sequence and intronic junctions of the EIF2AK4 gene, and compared clinical characteristics and outcomes between EIF2AK4 mutation carriers and non-carriers. Medical therapies approved for pulmonary arterial hypertension (prostacyclin derivatives, endothelin receptor antagonists and phosphodiesterase type-5 inhibitors) were given to patients according to the clinical judgment and discretion of treating physicians. The primary outcome was the event-free survival (death or transplantation). Secondary outcomes included response to therapies for pulmonary arterial hypertension and survival after lung transplantation. A satisfactory clinical response to specific therapy for pulmonary arterial hypertension was defined by achieving New York Heart Association functional class I or II, a 6-min walk distance of more than 440 m, and a cardiac index greater than 2·5 L/min per m² at the first reassessment after initiation of specific therapy for pulmonary arterial hypertension.

FINDINGS

We obtained data from Jan 1, 2003, to June 1, 2016, and identified 94 patients with sporadic or heritable PVOD/PCH (confirmed or highly probable). 27 (29%) of these patients had bi-allelic EIF2AK4 mutations. PVOD/PCH due to EIF2AK4 mutations occurred from birth to age 50 years, and these patients were younger at presentation than non-carriers (median 26·0 years [range 0-50.3] vs 60·0 years [6·7-81·4] years; p<0·0001). At diagnosis, both mutations carriers and non-carriers had similarly severe precapillary pulmonary hypertension and functional impairment. 22 (81%) of mutations carriers and 63 (94%) of non-carriers received therapy approved for pulmonary arterial hypertension. Drug-induced pulmonary oedema occurred in five (23%) of treated EIF2AK4 mutations carriers and 13 (21%) of treated non-carriers. Follow-up assessment after initiation of treatment showed that only three (4%) patients with PVOD/PCH reached the predefined criteria for satisfactory clinical response. The probabilities of event-free survival (death or transplantation) at 1 and 3 years were 63% and 32% in EIF2AK4 mutations carriers, and 75% and 34% in non-carriers. No significant differences occurred in event-free survival between the 2 groups (p=0·38). Among the 33 patients who had lung transplantation, estimated post-transplantation survival rates at 1, 2, and 5 years were 84%, 81%, and 73%, respectively.

INTERPRETATION

Heritable PVOD/PCH due to bi-allelic EIF2AK4 mutations is characterised by a younger age at diagnosis but these patients display similar disease severity compared with mutation non-carriers. Response to therapy approved for pulmonary arterial hypertension in PVOD/PCH is rare. PVOD/PCH is a devastating condition and lung transplantation should be considered for eligible patients.

FUNDING

None.

Pulmonary veno-occlusive disease

Pulmonary veno-occlusive disease (PVOD) is a rare form of pulmonary hypertension (PH) characterised by preferential remodelling of the pulmonary venules. In the current PH classification, PVOD and pulmonary capillary haemangiomatosis (PCH) are considered to be a common entity and represent varied expressions of the same disease. The recent discovery of biallelic mutations in the EIF2AK4 gene as the cause of heritable PVOD/PCH represents a major milestone in our understanding of the molecular pathogenesis of PVOD. Although PVOD and pulmonary arterial hypertension (PAH) share a similar clinical presentation, with features of severe precapillary PH, it is important to differentiate these two conditions as PVOD carries a worse prognosis and life-threatening pulmonary oedema may occur following the initiation of PAH therapy. An accurate diagnosis of PVOD based on noninvasive investigations is possible utilising oxygen parameters, low diffusing capacity for carbon monoxide and characteristic signs on high-resolution computed tomography of the chest. No evidence-based medical therapy exists for PVOD at present and lung transplantation remains the preferred definitive therapy for eligible patients.