Coronary artery disease and heart failure in patients with idiopathic pulmonary fibrosis

Decoding the complexity: mechanistic insights into comorbidities in idiopathic pulmonary fibrosis

The complex pathogenic relationships between idiopathic pulmonary fibrosis (IPF) and its usually associated comorbidities remain poorly understood. While evidence suggests that some comorbidities may directly influence the development or progression of IPF, or vice versa, whether these associations are causal or arise independently due to shared risk factors, such as ageing, smoking, lifestyle and genetic susceptibility, is still uncertain. Some comorbidities, such as metabolic syndromes, gastro-oesophageal reflux disease and obstructive sleep apnoea, precede the development of IPF. In contrast, others, such as pulmonary hypertension and lung cancer, often become apparent after IPF onset or during its progression. These timing patterns suggest a directional relationship in their associations. The issue is further complicated by the fact that patients often have multiple comorbidities, which may interact and exacerbate one another, creating a vicious cycle. To clarify these correlations, some studies have used causal inference methods (e.g. Mendelian randomisation) and exploration of underlying mechanisms; however, these efforts have not yet generated conclusive insights. In this review, we provide a general overview of the relationship between IPF and its comorbidities, emphasising the pathogenic mechanisms underlying each comorbidity, potential shared pathobiology with IPF and, when available, causal insights from Mendelian randomisation studies.

Incidence and clinical impact of coronary artery disease confirmed by coronary CT angiography in patients with interstitial lung disease

BACKGROUND

Patients with interstitial lung disease (ILD) who undergo routine chest computed tomography (CT) often have findings suggestive of coronary artery disease (CAD). However, the incidence and prognostic impact of significant CAD, confirmed by coronary CT angiography (CCTA), are not well established.

METHODS

From January 2013 to February 2024, we evaluated 215 patients from a retrospective ILD registry at our institute, who underwent CCTA as part of ILD management. Using the CAD-Reporting and Data System, we investigated the incidence of significant CAD and evaluated its impact on 5-year mortality and rehospitalization for respiratory or cardiovascular causes through multivariable Cox proportional hazards regression.

RESULTS

During a median follow-up of 2.3 years, CCTA was performed at a median of 5 months postdiagnosis of ILD in the cohort. Significant CAD was identified in 92 patients (42.8%), with 27 (12.6%) undergoing coronary revascularization. The presence of significant CAD was significantly associated with an increased risk of mortality (adjusted hazard ratio [HR]: 2.31; 95% confidence interval [CI]: 1.07 - 5.01; P = 0.03) and a higher risk of rehospitalization (adjusted HR: 2.03; 95% CI: 1.23 - 3.34; P = 0.01). Key clinical variables associated with significant CAD included older age (≥ 63 years), hypertension, and coronary calcification observed on non-gated chest CT.

CONCLUSIONS

CCTA-identified CAD was associated with a worse clinical prognosis in patients with ILD, with significant risk factors including older age, hypertension, and coronary calcification observed on non-gated chest CT. These findings suggest that obtaining CCTA may be beneficial for managing patients with ILD, particularly those with identified risk factors.

Echocardiographic Assessment of Biventricular Mechanics in Patients with Mild-to-Moderate Idiopathic Pulmonary Fibrosis: A Systematic Review and Meta-Analysis

Background: Over the last few years, a few imaging studies have performed conventional transthoracic echocardiography (TTE) implemented with speckle tracking echocardiography (STE) for the assessment of biventricular mechanics in patients with non-advanced idiopathic pulmonary fibrosis (IPF). This systematic review and meta-analysis aimed at evaluating the overall effect of mild-to-moderate IPF on the main indices of biventricular systolic function assessed by TTE and STE. Methods: All imaging studies assessing right ventricular (RV)-global longitudinal strain (GLS), left ventricular (LV)-GLS, tricuspid annular plane systolic excursion (TAPSE), and left ventricular ejection fraction (LVEF) in IPF patients vs. healthy controls, selected from PubMed, Scopus, and EMBASE databases, were included. Continuous data (RV-GLS, LV-GLS, TAPSE, and LVEF) were pooled as standardized mean differences (SMDs) comparing the IPF group with healthy controls. The SMD of RV-GLS was calculated using the random-effect model, whereas the SMDs of LV-GLS, TAPSE, and LVEF were calculated using the fixed-effect model. Results: The full texts of 6 studies with 255 IPF patients and 195 healthy controls were analyzed. Despite preserved TAPSE and LVEF, both RV-GLS and LV-GLS were significantly, although modestly, reduced in the IPF patients vs. the controls. The SMD was large (-1.01, 95% CI -1.47, -0.54, p < 0.001) for RV-GLS, medium (-0.62, 95% CI -0.82, -0.42, p < 0.001) for LV-GLS, small (-0.42, 95% CI -0.61, -0.23, p < 0.001) for TAPSE, and small and not statistically significant (-0.20, 95% CI -0.42, 0.03, p = 0.09) for LVEF assessment. Between-study heterogeneity was high for the studies assessing RV-GLS (I2 = 80.5%), low-to-moderate for those evaluating LV-GLS (I2 = 41.7%), and low for those measuring TAPSE (I2 = 16.4%) and LVEF (I2 = 7.63%). The Egger's test yielded a p-value of 0.60, 0.11, 0.31, and 0.68 for the RV-GLS, LV-GLS, TAPSE, and LVEF assessment, respectively, indicating no publication bias. On meta-regression analysis, none of the moderators was significantly associated with effect modification for RV-GLS (all p > 0.05). The sensitivity analysis supported the robustness of the results. Conclusions: RV-GLS impairment is an early marker of subclinical myocardial dysfunction in mild-to-moderate IPF. STE should be considered for implementation in clinical practice for early detection of RV dysfunction in IPF patients without advanced lung disease.

Blood urea nitrogen-to-albumin ratio as a new prognostic indicator of 1-year all-cause mortality in patients with IPF

Background

Idiopathic pulmonary fibrosis (IPF) is an interstitial lung disease characterized by chronic inflammation and progressive fibrosis. The blood urea nitrogen-to-albumin ratio (BAR) is a comprehensive parameter associated with inflammation status; however, it is unknown whether the BAR can predict the prognosis of IPF.

Methods

This retrospective study included 176 patients with IPF, and 1-year all-cause mortality of these patients was recorded. A receiver operating characteristic (ROC) curve was used to explore the diagnostic value of BAR for 1-year all-cause mortality in IPF patients, and the survival rate was further estimated using the Kaplan-Meier survival curve. Cox proportional hazards regression model and forest plot were used to assess the association between the BAR and 1-year all-cause mortality in IPF patients.

Results

The BAR of IPF patients was significantly higher in the non-survivor group than in the survivor group [0.16 (0.13-0.23) vs. 0.12 (0.09-0.17) mmol/g, p = 0.002]. The area under the ROC curve for predicting 1-year all-cause mortality in IPF patients was 0.671, and the optimal cut-off value was 0.12 mmol/g. The Kaplan-Meier survival curve showed that the 1-year cumulative survival rate of IPF patients with a BAR ≥0.12 was significantly decreased compared with the patients with a BAR <0.12. The Cox regression model and forest plot showed that the BAR was an independent prognostic biomarker for 1-year all-cause mortality in IPF patients (HR = 2.778, 95% CI 1.020-7.563, p = 0.046).

Conclusion

The BAR is a significant predictor of 1-year all-cause mortality of IPF patients, and high BAR values may indicate poor clinical outcomes.

Identification of shared molecular mechanisms and diagnostic biomarkers between heart failure and idiopathic pulmonary fibrosis

Background

Heart failure (HF) and idiopathic pulmonary fibrosis (IPF) are global public health concerns. The relationship between HF and IPF is widely acknowledged. However, the interaction mechanisms between these two diseases remain unclear, and early diagnosis is particularly difficult. Through the integration of bioinformatics and machine learning, our work aims to investigate common gene features, putative molecular causes, and prospective diagnostic indicators of IPF and HF.

Methods

The Gene Expression Omnibus (GEO) database provided the RNA-seq datasets for HF and IPF. Utilizing a weighted gene co-expression network analysis (WGCNA), possible genes linked to HF and IPF were found. The Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) were then employed to analyze the genes that were shared by HF and IPF. Using the cytoHubba and iRegulon algorithms, a competitive endogenous RNA (ceRNA) network was built based on seven basic diagnostic indicators. Additionally, hub genes were identified using machine learning approaches. External datasets were used to validate the findings. Lastly, the association between the number of immune cells in tissues and the discovered genes was estimated using the CIBERSORT method.

Results

In total, 63 shared genes were identified between HF- and IPF-related modules using WGCNA. Extracellular matrix (ECM)/structure organization, ECM-receptor interactions, focal, and protein digestion and absorption, were shown to be the most enrichment categories in GO and KEGG enrichment analysis of common genes. Furthermore, a total of seven fundamental genes, including COL1A1, COL3A1, THBS2, CCND1, ASPN, FAP, and S100A12, were recognized as pivotal genes implicated in the shared pathophysiological pathways of HF and IPF, and TCF12 may be the most important regulatory transcription factor. Two characteristic molecules, CCND1 and NAP1L3, were selected as potential diagnostic markers for HF and IPF, respectively, using a support vector machine-recursive feature elimination (SVM-RFE) model. Furthermore, the development of diseases and diagnostic markers may be associated with immune cells at varying degrees.

Conclusions

This study demonstrated that ECM/structure organisation, ECM-receptor interaction, focal adhesion, and protein digestion and absorption, are common pathogeneses of IPF and HF. Additionally, CCND1 and NAP1L3 were identified as potential diagnostic biomarkers for both HF and IPF. The results of our study contribute to the comprehension of the co-pathogenesis of HF and IPF at the genetic level and offer potential biological indicators for the early detection of both conditions.

A Step towards understanding coronary artery disease: a complication in idiopathic pulmonary fibrosis

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is a relatively rare disease with increasing incidence trends. Cardiovascular disease is a significant complication in IPF patients due to the role of common proatherogenic immune mediators. The prevalence of coronary artery disease (CAD) in IPF and the association between these distinct pathologies with overlapping pathophysiology remain less studied.

RESEARCH QUESTION

We hypothesised that IPF is an independent risk factor for CAD.

METHODS

We conducted a retrospective case-control study using the national inpatient sample (2017-2019). We included adult hospitalisations with IPF after excluding other interstitial lung diseases and other endpoints of CAD, acute coronary syndrome and old myocardial infarction. We examined their baseline characteristics, such as demographic data, hospital characteristics and socioeconomic status. The prevalence of cardiac risk factors and CAD was also compared between hospitalisations with and without IPF. Univariate and multivariate regression analysis was further performed to study the odds of CAD with IPF. The cases of IPF in the study population were propensity-matched, after which generalised linear modelling analysis was performed to validate the findings.

RESULTS

A total of 116 010 admissions were hospitalised in 2017-2019 with IPF, of which 55.6% were men with a mean age of 73 years. Adult hospitalisations with IPF were found to have a higher prevalence of diabetes mellitus (29.3% vs 24.0%; p<0.001), hypertension (35.6% vs 33.8%; p<0.001), hyperlipidaemia (47.7% vs 30.2%; p<0.0001) and tobacco abuse (41.7% vs 20.9%; p<0.001), while they had a lower prevalence of obesity (11.7% vs 15.3%; p<0.0001) compared with hospitalisations without IPF. Multivariate logistic regression analysis revealed 28% higher odds of developing CAD in IPF hospitalisations (OR -1.28; CI 1.22 to 1.33; p<0.001). Postpropensity matching, generalised linear modelling analysis revealed even higher odds of CAD with IPF (OR -1.77; CI 1.54 to 2.02; p<0.001) CONCLUSIONS: Our study found a higher prevalence of CAD in IPF hospitalisations and significantly higher odds of CAD among IPF cases. IPF remains a terminal lung disease that portends a poor prognosis, but addressing the cardiovascular risk factors in these patients can help reduce the case fatality rate due to the latter and potentially add to quality-adjusted life years.

Treatment of idiopathic pulmonary fibrosis and progressive pulmonary fibrosis: A position statement from the Thoracic Society of Australia and New Zealand 2023 revision

Idiopathic pulmonary fibrosis (IPF) is a progressive disease leading to significant morbidity and mortality. In 2017 the Thoracic Society of Australia and New Zealand (TSANZ) and Lung Foundation Australia (LFA) published a position statement on the treatment of IPF. Since that time, subsidized anti-fibrotic therapy in the form of pirfenidone and nintedanib is now available in both Australia and New Zealand. More recently, evidence has been published in support of nintedanib for non-IPF progressive pulmonary fibrosis (PPF). Additionally, there have been numerous publications relating to the non-pharmacologic management of IPF and PPF. This 2023 update to the position statement for treatment of IPF summarizes developments since 2017 and reaffirms the importance of a multi-faceted approach to the management of IPF and progressive pulmonary fibrosis.

Coronary artery calcium score is a prognostic factor for mortality in idiopathic pulmonary fibrosis

BACKGROUND

Cardiovascular diseases are frequent in idiopathic pulmonary fibrosis (IPF) and impact on survival. We investigated the association of coronary artery calcium (CAC) score at IPF diagnosis and during mid-term follow-up, with adverse cardiovascular events and all-cause mortality.

METHODS

Consecutive patients with IPF were retrospectively analyzed. Demographic data, smoking history, comorbidities and pulmonary function tests (PFTs) were recorded. All patients had at least two chest high resolution computed tomography (HRCT) performed 2 years apart. The total CAC score and visual fibrotic score were calculated, and all clinically significant cardiovascular events and deaths were reported.

RESULTS

The population consisted of 79 patients (57 males, mean age: 74.4±7.6 years); 67% of patients had a history of smoking, 48% of hypertension, 37% of dyslipidemia and 22.8% of diabetes. The visual score was 21.28±7.99% at T0 and 26.54±9.34% at T1, respectively (T1-T0 5.26±6.13%, P<0.001). CAC score at T0 and at T1 was 537.93±839.94 and 759.98±1027.6, respectively (T1-T0 224.66±406.87, P<0.001). Mean follow-up time was 2.47±1.1 years. On multivariate analysis, male sex (HR=3.58, 95% CI: 1.14-11.2) and CAC score at T0 (HR=1.04, 95% CI: 1.01-1.07) correlated with mortality and cardiovascular events. CAC score at T0≥405 showed 82% sensitivity and 100% specificity for predicting mortality and adverse cardiovascular events.

CONCLUSIONS

IPF patients with a CAC score at diagnosis ≥405 have a poor prognosis over a mid-term follow-up. A higher CAC score is associated with mortality and cardiovascular events.

Comparison of clinical scoring to predict mortality risk in mild-to-moderate idiopathic pulmonary fibrosis

BACKGROUND

During the last decade, a number of clinical scores, such as Gender-Age-Physiology (GAP) Index, TORVAN Score and Charlson Comorbidity Index (CCI), have been separately used to measure comorbidity burden in idiopathic pulmonary fibrosis (IPF). However, no previous study compared the prognostic value of these scores to assess mortality risk stratification in IPF patients with mild-to-moderate disease.

METHODS

All consecutive patients with mild-to-moderate IPF who underwent high-resolution computed tomography, spirometry, transthoracic echocardiography and carotid ultrasonography at our Institution, between January 2016 and December 2018, were retrospectively analyzed. GAP Index, TORVAN Score and CCI were calculated in all patients. Primary endpoint was all-cause mortality, whereas secondary endpoint was the composite of all-cause mortality and rehospitalizations for all-causes, over medium-term follow-up.

RESULTS

Seventy IPF patients (70.2±7.4 yrs, 74.3% males) were examined. At baseline, GAP Index, TORVAN Score and CCI were 3.4±1.1, 14.7±4.1 and 5.3±2.4, respectively. A strong correlation between coronary artery calcification (CAC) and common carotid artery (CCA) intima-media thickness (IMT) (r=0.88), CCI and CAC (r=0.80), CCI and CCA-IMT (r=0.81), was demonstrated in the study group. Follow-up period was 3.5±1.2 years. During follow-up, 19 patients died and 32 rehospitalizations were detected. CCI (HR 2.39, 95% CI: 1.31-4.35) and heart rate (HR 1.10, 95% CI: 1.04-1.17) were independently associated with primary endpoint. CCI (HR 1.54, 95% CI: 1.15-2.06) predicted secondary endpoint, also. A CCI ≥6 was the optimal cut-off for predicting both outcomes.

CONCLUSIONS

Due to the increased atherosclerotic and comorbidity burden, IPF patients with CCI ≥6 at an early-stage disease have poor outcome over medium-term follow-up.

Left-sided heart failure burden and mortality in idiopathic pulmonary fibrosis: a population-based study

Background

Cardiovascular disease is prevalent in idiopathic pulmonary fibrosis (IPF), yet the extent of left-sided heart failure (HF) burden, whether this has changed with time and whether HF impacts mortality risk in these patients are unknown. The aims of this study were therefore to determine the temporal trends in incidence and prevalence of left-sided HF in patients with IPF in England and compare these to published estimates in the general population and those with comparable chronic respiratory conditions such as chronic obstructive pulmonary disease (COPD), as well as determine the risk of all-cause and cause-specific mortality in patients with comorbid left-sided HF and IPF at population-level using electronic healthcare data.

Methods

Clinical Practice Research Datalink (CPRD) Aurum primary-care data linked to mortality and secondary-care data was used to identify IPF patients in England. Left-sided HF prevalence and incidence rates were calculated for each calendar year between 2010 and 2019, stratified by age and sex. Risk of all-cause, cardiovascular and IPF-specific mortality was calculated using multivariate Cox regression.

Results

From 40,577patients with an IPF code in CPRD Aurum, 25, 341 IPF patients met inclusion criteria. Left-sided HF prevalence decreased from 33.4% (95% CI 32.2–34.6) in 2010 to 20.9% (20.0–21.7) in 2019. Left-sided HF incidence rate per 100 person-years (95% CI) remained stable between 2010 and 2017 but decreased from 4.3 (3.9–4.8) in 2017 to 3.4 (3.0–3.9) in 2019. Throughout follow-up, prevalence and incidence were higher in men and with increasing age. Comorbid HF was associated with poorer survival (adjusted HR (95%CI) 1.08 (1.03–1.14) for all-cause mortality; 1.32 (1.09–1.59) for cardiovascular mortality).

Conclusion

Left-sided HF burden in IPF patients in England remains high, with incidence almost 4 times higher than in COPD, a comparable lung disease with similar cardiovascular risk factors. Comorbid left-sided HF is also a poor prognostic marker. More substantial reduction in left-sided HF prevalence than incidence suggests persistently high IPF mortality. Given rising IPF incidence in the UK, this calls for better management of comorbidities such as left-sided HF to help optimise IPF survival.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12890-022-01973-5.