Diagnostic and prognostic role of biomarkers for pulmonary hypertension in interstitial lung disease

Unmasking a Silent Threat: Improving Pulmonary Hypertension Screening Methods for Interstitial Lung Disease Patients

This article provides a comprehensive overview of the latest literature on the diagnostics and treatment of pulmonary hypertension (PH) associated with interstitial lung disease (ILD). Heightened suspicion for PH arises when the advancement of dyspnoea in ILD patients diverges from the expected pattern of decline in pulmonary function parameters. The complexity of PH associated with ILD (PH-ILD) diagnostics is emphasized by the limitations of transthoracic echocardiography in the ILD population, necessitating the exploration of alternative diagnostic approaches. Cardiac magnetic resonance imaging (MRI) emerges as a promising tool, offering insights into hemodynamic parameters and providing valuable prognostic information. The potential of biomarkers, alongside pulmonary function and cardiopulmonary exercise tests, is explored for enhanced diagnostic and prognostic precision. While specific treatments for PH-ILD remain limited, recent studies on inhaled treprostinil provide new hope for improved patient outcomes.

Pulmonary Hypertension in Interstitial Lung Disease: Updates in Disease, Diagnosis, and Therapeutics

Pulmonary hypertension is a debilitating condition that frequently develops in the setting of interstitial lung disease, likely related to chronic alveolar hypoxemia and pulmonary vascular remodeling. This disease process is likely to be identified more frequently by providers given recent advancements in definitions and diagnostic modalities, and provides practitioners with emerging opportunities to improve patient outcomes and quality of life. Despite years of data suggesting against the efficacy of pulmonary vasodilator therapy in patients with pulmonary hypertension due to interstitial lung disease, new data have emerged identifying promising advancements in therapeutics. The authors present to you a comprehensive review of pulmonary hypertension in interstitial lung disease, reviewing our current understanding of pathophysiology, updates in diagnostic approaches, and highlights of recent clinical trials which provide an effective approach for medical management.

The PH-ILD Detection tool: External validation and use in patients with ILD

Pulmonary hypertension (PH) results in increased morbidity and mortality in patients with interstitial lung disease (ILD). Early recognition of PH in this population is essential for planning diagnostic testing, initiating therapy, and evaluating for lung transplantation. The previously developed PH-ILD Detection tool has significant potential in the evaluation and treatment of ILD patients; the aim of this study was to validate the tool in an independent, multicenter cohort of patients. We conducted a retrospective review of prospectively collected data from 161 ILD patients. Patients were stratified into low- (n = 78, 48.4%), intermediate- (n = 54, 33.5%), and high-risk (n = 29, 18.0%) groups based on the score obtained with the tool. Intermediate- and high-risk patients underwent follow-up echocardiogram (TTE); 49.4% (n = 41) had an abnormal TTE suggestive of underlying PH. These patients underwent right heart catheterization; PH-ILD was diagnosed in 73.2% (n = 30) of these cases. The PH-ILD Detection tool has a sensitivity of 93.3%, specificity of 90.9%, and area-under-the-curve of 0.921 for diagnosing PH in ILD patients, validating the findings from the original study and establishing the tool as a fundamental resource for early recognition of PH in ILD patients.

Current best clinical practices for monitoring of interstitial lung disease

INTRODUCTION

Interstitial lung diseases (ILDs) are a heterogeneous group of inflammatory and/or fibrotic conditions with variable outcome and often a dismal prognosis. Since many ILDs are progressive in nature, monitoring of signs and symptoms of progression is essential to inform treatment decisions and patient counseling. Monitoring of ILDs is a multimodality process and includes all aspects of the disease, e.g. measurement of pulmonary function and exercise capacity, symptom registration and quality of life (QoL), imaging, comorbidities and/or involvement of other organs to assess disease activity, symptom burden, treatment effects, adverse events, the need for supportive and palliative care, and lung transplantation.

AREAS COVERED

For this narrative review, we searched the PUBMED database to identify articles relevant for monitoring ILDs, including pulmonary function tests, exercise capacity, imaging, telemedicine, symptoms, and QoL.

EXPERT OPINION

Due to the high heterogeneity of the ILDs and their disease course, an individualized multimodality approach must be applied. Future strategies include use of telemedicine for home monitoring of lung function and symptoms, use of artificial intelligence to support automatized guidance of patients, computerized evaluation of ILD changes on imaging, and new imaging tools with less radiation dosage.

Comorbidity in idiopathic pulmonary fibrosis - what can biomarkers tell us?

Idiopathic pulmonary fibrosis (IPF) is characterized by progressive parenchymal scarring, leading to dyspnoea, respiratory failure and premature death. Although IPF is confined to the lungs, the importance of IPF comorbidities such as pulmonary hypertension and ischaemic heart disease, lung cancer, emphysema/chronic obstructive pulmonary disease, gastroesophageal reflux, sleep apnoea and depression has been increasingly recognized. These comorbidities may be associated with increased mortality and significant loss of quality of life, so their identification and management are vital. The development of good-quality biomarkers could lead to numerous gains in the management of these patients. Biomarkers can be used for the identification of predisposed individuals, early diagnosis, assessment of prognosis, selection of best treatment and assessment of response to treatment. However, the role of biomarkers for IPF comorbidities is still quite limited, and mostly based on evidence coming from populations without IPF. The future development of new biomarker studies could be informed by those that have been studied independently for each of these conditions. For now, clinicians should be mostly attentive to clinical manifestations of IPF comorbidities, and use validated diagnostic methods for diagnosis. As research on biomarkers of most common diseases continues, it is expected that useful biomarkers are developed for these diseases and then validated for IPF populations. The reviews of this paper are available via the supplemental material section.

Chemokine signaling axis between endothelial and myeloid cells regulates development of pulmonary hypertension associated with pulmonary fibrosis and hypoxia

Pulmonary hypertension complicates the care of many patients with chronic lung diseases (defined as Group 3 pulmonary hypertension), yet the mechanisms that mediate the development of pulmonary vascular disease are not clearly defined. Despite being the most prevalent form of pulmonary hypertension, to date there is no approved treatment for patients with disease. Myeloid-derived suppressor cells (MDSCs) and endothelial cells in the lung express the chemokine receptor CXCR2, implicated in the evolution of both neoplastic and pulmonary vascular remodeling. However, precise cellular contribution to lung disease is unknown. Therefore, we used mice with tissue-specific deletion of CXCR2 to investigate the role of this receptor in Group 3 pulmonary hypertension. Deletion of CXCR2 in myeloid cells attenuated the recruitment of polymorphonuclear MDSCs to the lungs, inhibited vascular remodeling, and protected against pulmonary hypertension. Conversely, loss of CXCR2 in endothelial cells resulted in worsened vascular remodeling, associated with increased MDSC migratory capacity attributable to increased ligand availability, consistent with analyzed patient sample data. Taken together, these data suggest that CXCR2 regulates MDSC activation, informing potential therapeutic application of MDSC-targeted treatments.

Role of Pro-Brain Natriuretic Peptide Serum Concentration in the Detection of Pulmonary Hypertension in Patients With End-Stage Lung Diseases Referred for Lung Transplantation

BACKGROUND

Serum N-terminal pro-brain natriuretic peptide (NT-proBNP) concentration is elevated in patients with pulmonary hypertension (PH); however, its role in the detection of PH associated with lung disease is not well established.

AIM

The aim of this study was to assess the value of NT-proBNP in the detection of PH in patients with end-stage lung disease (esLD) referred for lung transplantation.

MATERIALS AND METHODS

The study population consisted of 65 patients: 37 with idiopathic pulmonary fibrosis (IPF), 20 with chronic obstructive pulmonary disease, and 8 patients with other interstitial lung diseases (75% men, mean age 53.3 ± 9.5 years). Serum concentration of NT-proBNP was assessed with an immunoradiometric assay kit. The mean pulmonary artery pressure (mPAP) was measured using a Swan-Ganz catheter. PH was defined as mPAP ≥ 25 mm Hg.

RESULTS

Median NT-proBNP concentrations were significantly higher in patients with PH than in patients without PH: 139 (49-1236) pg/mL vs 67 (38-116) pg/mL, respectively; P = .016. Receiver operating characteristic (ROC) analysis revealed that NT-proBNP concentration higher than 131.5 pg/mL was a predictor of PH with good specificity (81%) and positive predictive value (78.9%) but low sensitivity (55.6%) and negative predictive value (58.6%). The area under the ROC curve of serum NT-proBNP concentration for PH was 0.71 (95% confidence interval 0.57-0.85, P = .039).

CONCLUSION

Serum concentration of NT-proBNP may be useful in the diagnosis of PH in patients with esLD referred for lung transplantation.

Pulmonary hypertension in patients with interstitial lung disease

Interstitial lung diseases (ILDs) comprise a broad and heterogeneous group of more than two hundred diseases with common functional characteristics. Their diagnosis and management require a multidisciplinary approach. This multidisciplinary approach involves the assessment of comorbid conditions including pulmonary hypertension (PH) that exerts a dramatic impact on survival. The current World Health Organization (WHO) classification of PH encompasses many of the interstitial lung diseases into WHO Group 3, while sarcoidosis, Pulmonary Langerhans Cell Histiocytosis and lymphangioleiomyomatosis are placed into WHO Group 5 as diseases with unclear or multifactorial mechanisms. Connective tissue diseases could span any of the 5 WHO groups based on the primary phenotype into which they manifest. Interestingly, several challenging phenotypes present with features that overlap between two or more WHO PH groups. Currently, PH-specific treatment is recommended only for patients classified into WHO Group 1 PH. The lack of specific treatment for other groups, including PH in the setting of ILD, reflects the poor outcomes of these patients. Thus, identification of the optimal strategy for ILD patients with PH remains an amenable need. This review article provides a brief overview of biomarkers indicative of vascular remodeling in interstitial lung disease, summarizes the current state of knowledge regarding patients with PH and ILD and highlights future perspectives that remain to be addressed.

Fractional Exhaled Nitric Oxide Measurement in Pulmonary Hypertension: A Follow-Up Study

Pulmonary hypertension (PH) is a fatal disease although significant improvements in treatment are achieved. Easily implemented and noninvasive prognostic techniques are needed while following-up these patients. The aim was to investigate the role of fractional exhaled nitric oxide (FeNO) in follow-up for patients with PH. In this longitudinal study, patients with pulmonary arterial hypertension (PAH) and chronic thromboembolic PH (CTEPH) who were seen in PH Outpatient Clinic, Istanbul Faculty of Medicine, Istanbul University, were enrolled in the study. Echocardiography, 6-minute walking test, brain natriuretic peptide, and FeNO measurements were performed, and World Health Organization functional class was evaluated to all patients at baseline, and third, and sixth months. Right-heart catheterization and pulmonary function tests at the time of diagnosis were recorded. The study comprised 31 patients (23 women, 8 men; mean age: 53.4 ± 17.1 years) with PAH (n = 19) and CTEPH (n = 12) and 80 healthy controls. Patients with PH had lower FeNO values than the control group (16.5 ppb vs 19.8 ppb; P < .05). Fractional exhaled nitric oxide values did not change during follow-up and did not correlate with other follow-up measures except tricuspid annular plane systolic excursion values. Fractional exhaled nitric oxide was higher in the idiopathic PAH subgroup at baseline and at third month than patients with PAH associated with other diseases. Fractional exhaled nitric oxide did not change in patients who had clinical deterioration. As a conclusion; Patients with PH had lower FeNO values than healthy controls, but FeNO did not change significantly during follow-up. Large-scale studies with prolonged follow-up periods are needed to understand the role of FeNO in the follow-up of the patients with PH.

[Clinical significance of hypersensitive C-reactive protein, fribrinogen and D-dimmer in connective tissue disease-related interstitial lung disease]

OBJECTIVE

To investigate the clinical significance of plasma levels of hypersensitive C-reactive protein (hs-CRP), fibriogen and D-dimmer (D-DI) in patients with connective tissue disease (CTD)-related interstitial lung disease (CTD-ILD).

METHODS

Sixty-nine patients with interstitial lung disease admitted in Zhujiang Hospital between January, 2010 and April, 2016, including 29 with CTD-ILD and 40 with non-CTD-ILD were analyzed for plasma levels of hs-CRP, fibriogen and D-DI, with 25 healthy subjects as the control group.

RESULTS

The plasma level of hs-CRP, fibriogen and D-DI in patients with CTD-ILD and non-CTD-ILD were all significantly higher than those in the control group. The patients with CTD-ILD had a significantly higher hs-CRP level than those with non-CTD-ILD, but the levels of fibriogen and D-DI were comparable between the two groups. Correlation analysis indicated that Hs-CRP level was positively correlated with the levels of D-DI (r=0.539, P<0.01) and fibrinogen (r=0.534, P<0.01).

CONCLUSION

Hs-CRP, fibriogen and D-DI levels show an important value in clinical diagnosis of CTD, and an obvious elevation of hs-CRP is correlated with the CTD.

NT-proBNP <95 ng/l can exclude pulmonary hypertension on echocardiography at diagnostic workup in patients with interstitial lung disease

Background

Pulmonary hypertension (PH) is a serious complication to interstitial lung disease (ILD) and has a poor prognosis. PH is often diagnosed by screening with echocardiography followed by right heart catheterisation. A previous study has shown that a value of NT-pro-brain natriuretic peptide (NT-proBNP) <95 ng/l could be used to rule out PH in patients with ILD.

Aim

To evaluate this rule-out test for PH in a new cohort of incident patients with ILD.

Methods

An established database with data from 148 consecutive patients referred from January 2012 to October 2014 was used to identify patients and obtain data from echocardiography, NT-proBNP, diagnosis and lung function. Signs of PH on echocardiography were defined as a tricuspid pressure gradient (TR) ≥40 mmHg, decreased right ventricular systolic function or dilatation. Sensitivity, specificity, negative predictive value (NPV) and positive predictive value (PPV) of NT-proBNP >95 ng/l for signs of PH on echocardiography were calculated. The study was approved by the Danish Health Authority.

Results

In 118 patients, data from both echocardiography and measurements of NT-proBNP were available. Eleven of these were screened positive for PH on echocardiography. Sensitivity, specificity, NPV and PPV of NT-proBNP <95 ng/l for PH were 100, 44, 16 and 100%, respectively. Furthermore, no patients with left heart failure as the cause of dyspnoea were missed using this cut-off value.

Conclusion

NT-proBNP <95 ng/l precludes a positive echocardiographic screen for PH in ILD patients at referral for diagnostic workup.

Efficacy of Statin Therapy in Pulmonary Arterial Hypertension: A Systematic Review and Meta-Analysis

Since the evidence regarding statin therapy in PAH has not been conclusive, we assessed the impact of statin therapy in PAH through a systematic review and meta-analysis of available studies. We searched selected databases up to August 1, 2015 to identify the studies investigating the effect of statin administration on PAH. Meta-analysis was performed using either a fixed-effects or random-effect model according to I(2) statistic. Meta-analysis of 8 studies with 665 patients did not suggest any significant improvement in 6-min walking distance (6MWD) by statin therapy (weighed mean difference [WMD]: -6.08 m, 95% confidence interval [CI]: -25.66, 13.50, p = 0.543; Q = 8.41, I(2) = 28.64%). Likewise, none of the other indices including pulmonary arterial pressure (WMD: -0.97 mmHg, 95%CI: -4.39, 2.44, p = 0.577; Q = 14.64, I(2) = 79.51%), right atrial pressure (WMD: 1.01 mmHg, 95%CI: -0.93, 2.96, p = 0.307; Q = 44.88, I(2) = 95.54%), cardiac index (WMD: 0.05 L/min/m(2), 95%CI: -0.05, 0.15, p = 0.323; Q = 3.82, I(2) = 21.42%), and pulmonary vascular resistance (WMD: -1.42 dyn*s/cm(5), 95%CI: -72.11, 69.27, p = 0.969; Q = 0.69, I(2) = 0%) was significantly altered by statin therapy. In conclusion, the results of the meta-analysis did not show a statistically significant effect of statin therapy in the improvement of 6MWD, pulmonary arterial pressure, right atrial pressure, cardiac index and pulmonary vascular resistance.

Suspected pulmonary embolism in patients with pulmonary fibrosis: Discordance between ventilation/perfusion SPECT and CT pulmonary angiography

BACKGROUND AND OBJECTIVE

Pulmonary embolism (PE) is a common differential diagnosis in patients with pulmonary fibrosis presenting with a clinical deterioration. Both ventilation/perfusion (V/Q)-single photon emission computed tomography (SPECT) and computed tomographic pulmonary angiography (CTPA) are routinely used to detect PE. However, the value of V/Q-SPECT and CTPA in this scenario has not been studied so far. We aimed to investigate the concordance of V/Q-SPECT and CTPA in patients with pulmonary fibrosis and suspicion of pulmonary embolism.

METHODS

A total of 22 consecutive patients with pulmonary fibrosis and clinical deterioration who underwent both V/Q-SPECT and CTPA were included in the study and analyzed for the presence of pulmonary embolism.

RESULTS

Nine of 22 patients (41%) had evidence for pulmonary embolism in V/Q-SPECT, and two of these patients had matching evidence for pulmonary embolism in CTPA. In the other seven patients with positive findings in V/Q-SPECT, no evidence of pulmonary embolism was found in CTPA. None of the 13 patients with a negative V/Q-SPECT had evidence for pulmonary embolism in CTPA.

CONCLUSION

In patients with pulmonary fibrosis and suspected pulmonary embolism, pulmonary embolism is detected more frequently by V/Q-SPECT than by CTPA. Thromboembolic disease is identified on CTPA only in a minority of patients with positive findings on V/Q-SPECT. When making treatment decisions, clinicians should be aware of the high rate of discordant findings in V/Q-SPECT and CTPA in this specific patient population.

Under-recognised co-morbidities in idiopathic pulmonary fibrosis: A review

Co-morbidities in idiopathic pulmonary fibrosis are common. These co-morbidities include obstructive sleep apnoea, gastro-oesophageal reflux disease, pulmonary hypertension and depression. The presence of co-morbidities among patients with idiopathic pulmonary fibrosis contributes to worse quality of life, morbidity and mortality. Despite the high prevalence of certain co-morbidities in idiopathic pulmonary fibrosis, the optimal screening and management of many of these conditions remains unclear. The impact of co-morbidities on this patient population is becoming more apparent. Their relevance will only increase as significant effort is being made to develop novel therapeutics that will alter the disease trajectory of patients with idiopathic pulmonary fibrosis. The purpose of this review is to focus on the epidemiology, pathophysiology, diagnosis and management of select co-morbidities, including obstructive sleep apnoea, gastro-oesophageal reflux disease, pulmonary hypertension and depression, in idiopathic pulmonary fibrosis.

Influence of pulmonary hypertension on survival in advanced lung disease

BACKGROUND

Effects of pulmonary hypertension (PH) in advanced lung disease remain unclear.

METHODS

The United Network for Organ Sharing database was queried from 1987 to 2013 to assess survival lung transplant candidates to determine influence of PH in advanced lung disease. Thresholds included mean pulmonary artery pressure ≥ 25 mmHg (mild PH) and 35 mmHg (severe PH).

RESULTS

Of 12,405 listed possible candidates, 10,158 were used for univariate analysis, 7050 for Kaplan-Meier (KM) function, 6196 for multivariate Cox models, and 5328 (mild PH) and 1910 (severe PH) for propensity score matching (PSM). For mild and severe PH, univariate revealed that PH was associated with survival difference (HR = 1.530, 95% CI 1.416, 1.654, p < 0.001) and (HR = 2.033, 95% CI 1.851, 2.232, p < 0.001), respectively. KM function curves demonstrated a significant difference for mild PH (Log-rank test: Chi square (df = 1): 117.76, p < 0.0001) and severe PH (Log-rank test: Chi square (df = 1): 230.91, p < 0.0001). Multivariate Cox models also found a significant increased risk for death for mild PH (HR = 1.750, 95% CI 1.606, 1.907, p < 0.001) and severe PH (HR = 2.088, 95% CI 1.879, 2.319, p < 0.001). PSM confirmed this increased risk for death for mild PH (HR = 1.695, 95% CI 1.502, 1.914, p < 0.001) and severe PH (HR = 1.976, 95% CI 1.641, 2.379, p < 0.001).

CONCLUSIONS

PH is associated with significant increased risk for death in patients with advanced lung disease.

Pulmonary hypertension in chronic obstructive and interstitial lung diseases

The purpose of the present review is to summarize the current knowledge on PH in relation to COPD and ILD from a clinical perspective with emphasis on diagnosis, biomarkers, prevalence, impact, treatment, and practical implications. PH in COPD and ILD is associated with a poor prognosis, and is considered one of the most frequent types of PH. However, the prevalence of PH among patients with COPD and ILD is not clear. The diagnosis of PH in chronic lung disease is often established by echocardiographic screening, but definitive diagnosis requires right heart catheterization, which is not systematically performed in clinical practice. Given the large number of patients with chronic lung disease, biomarkers to preclude or increase suspicion of PH are needed. NT-proBNP may be used as a rule-out test, but biomarkers with a high specificity for PH are still required. It is not known whether specific treatment with existent drugs effective in pulmonary arterial hypertension (PAH) is beneficial in lung disease related PH. Studies investigating existing PAH drugs in animal models of lung disease related PH have indicated a positive effect, and so have case reports and open label studies. However, treatment with systemically administered pulmonary vasodilators implies the risk of worsening the ventilation-perfusion mismatch in patients with lung disease. Inhaled vasodilators may be better suited for PH in lung disease, but new treatment modalities are also required.