Idiopathic pleuroparenchymal fibroelastosis (IPPFE) is a rare interstitial lung disease characterized by upper-lobe-predominant fibrosis and thoracic cage deformity. However, its electrocardiographic (ECG) features remain poorly defined. We retrospectively analyzed ECG, echocardiography, and chest computed tomography (CT) findings in 20 patients with IPPFE and 18 with idiopathic pulmonary fibrosis (IPF). Patients with IPPFE showed a more rightward QRS axis than those with IPF (median +70.5° [interquartile range (IQR) 55.3–77.3] vs. +32.5° [IQR 1.3–63.5], p=0.007). The PR interval was shorter in IPPFE but within normal limits. CT showed greater upward displacement of the pulmonary hila. No significant correlations were found between QRS axis and hilar elevation, flat chest index, or echocardiographic indices. These findings suggest that the rightward QRS axis shift may reflect altered cardiac orientation associated with thoracic deformity rather than overt pulmonary hypertension. ECG abnormalities may aid recognition of IPPFE, particularly when radiological findings are subtle.
La fibroelastosis pleuroparenquimatosa idiopática (FEPPI) es una neumopatía intersticial rara que se caracteriza por la fibrosis predominante en los lóbulos superiores y la deformidad de la caja torácica, pero cuyas manifestaciones electrocardiográficas no se conocen bien. En este estudio retrospectivo hemos analizado los electrocardiogramas, los ecocardiogramas y las tomografías computarizadas (TC) de 20 pacientes con FEPPI y 18 pacientes con fibrosis pulmonar idiopática (FPI). El eje del QRS de los pacientes con FEPPI está más desviado a la derecha que el de los pacientes con FPI: mediana de +70,5° e intervalo intercuartílico (IIC) de 55,3-77,3, frente a +32,5° (IIC de 1,3-63,5); p=0,007. El intervalo PR es más corto en la FEPPI, aunque dentro de los límites normales. En las TC se aprecia un mayor desplazamiento ascendente de los hilios pulmonares. No se observa correlación significativa entre el eje del QRS y la elevación hiliar, el índice torácico ni los índices ecocardiográficos. Estos resultados indican que la desviación del eje del QRS hacia la derecha posiblemente refleje la orientación alterada del corazón, secundaria a la deformidad torácica, más que una hipertensión pulmonar franca. Las alteraciones electrocardiográficas pueden servir para reconocer la FEPPI, en particular cuando los signos radiográficos son sutiles.
Idiopathic pleuroparenchymal fibroelastosis (IPPFE) is a recently recognized and relatively rare interstitial lung disease characterized by upper-lobe-predominant subpleural fibrosis and elastosis.1,2 IPPFE exhibits distinct clinical and radiologic features such as progressive weight loss, restrictive ventilatory impairment, thoracic cage flattening (platythorax), and bilateral apical fibrosis on imaging.3–6 As the disease progresses, marked anatomical changes occur in the thorax and mediastinum, including platythorax and upward deviation of the pulmonary hilum.7,8 However, the implications of these structural changes for the heart and electrocardiographic (ECG) findings remain largely unknown. Although several reports have documented an association between IPPFE and pulmonary hypertension (PH),9,10 the underlying mechanisms remain speculative. In other forms of interstitial lung disease (ILD), PH is known to affect ECG findings, including the rightward deviation of the QRS axis and P-wave morphology. However, whether ECG axis deviation occurs in IPPFE and whether it reflects pulmonary hypertension or thoracic deformity has not been systematically investigated. In this study, we analyzed ECG findings in patients with IPPFE and compared them with those in patients with idiopathic pulmonary fibrosis (IPF). We also examined thoracic morphology using chest computed tomography (CT) and evaluated the right heart function and pressure using transthoracic echocardiography (TTE) to explore potential correlations between ECG axis deviation and structural or hemodynamic abnormalities.
We retrospectively identified 20 patients with IPPFE and 18 patients with IPF who had been followed up at our institution between January 2020 and December 2024 and who had available data for ECG, chest CT, and TTE within a 3-month interval. This study was approved by the institutional ethics committee (approval no. C25-05-004). Owing to the retrospective nature of the study, the requirement for informed consent was waived. All patients met the established diagnostic criteria for IPPFE or IPF and had no known cardiac comorbidities, such as ischemic heart disease, valvular disease, or arrhythmia requiring medication. Twelve-lead ECGs were obtained from patients at rest. The QRS duration and PR, QT, and RR intervals were automatically measured and manually verified. The presence of axis deviation, atrioventricular block, bundle branch block, and low voltage was also assessed. Chest CT was used to assess thoracic morphology, including the hilar elevation ratio (calculated as the vertical distance from the lung apex to the hilum divided by the distance from the apex to the diaphragm),7 as a surrogate index of hilar upward deviation. Platythorax was defined as flattening of the anteroposterior diameter of the thoracic cage on axial Images.4,11 The flat chest index was defined as the ratio of the anteroposterior diameter of the right thoracic cage to the transverse diameter of the thoracic cage on chest CT images at the level of the sixth thoracic vertebra.11 In addition, the presence of coexisting lower-lobe dominant fibrotic changes suggestive of usual interstitial pneumonia (UIP)-like features was recorded. TTE was performed by certified sonographers, using standard protocols. The following parameters were recorded: left ventricular ejection fraction (LVEF), tricuspid annular plane systolic excursion (TAPSE), tricuspid regurgitation pressure gradient (TRPG), and estimated right ventricular systolic pressure (RVSP). Statistical analyses were performed using EZR (Saitama Medical Center, Jichi Medical University, Japan). Continuous variables were assessed for normality using histograms. Between-group comparisons were conducted using the unpaired t-test or Mann–Whitney U test, as appropriate. Correlations between QRS axis and clinical or imaging parameters were evaluated using Pearson's or Spearman's correlation coefficients. A two-sided p-value <0.05 was considered statistically significant.
Baseline characteristics of the 20 patients with IPPFE are summarized in Table 1A. The clinical profile, including low body mass index, restrictive ventilatory impairment, platythorax (low flat chest index), and preserved arterial oxygenation, was consistent with previous reports.2,3 Pulmonary function did not differ between IPPFE and IPF. Chest CT showed a significantly higher hilar elevation ratio in IPPFE (median 0.38 vs. 0.32, p=0.0001), and lower-lobe UIP-like changes were present in 35% (Table 1). ECG findings are summarized in Table 1B. The median QRS axis was more rightward in IPPFE than in IPF (+70.5° [IQR 55.3–77.3] vs. +32.5° [IQR 1.3–63.5], p=0.007). The PR interval was shorter in IPPFE (p=0.014) but remained below the threshold for first-degree atrioventricular block. RR interval and QRS duration did not differ between groups, and no patients met criteria for right bundle branch block or low voltage. TTE showed no differences in RVSP, TAPSE, or LVEF. Within the IPPFE group, QRS axis was not correlated with hilar elevation, flat chest index, pulmonary function (%FVC, RV/TLC %pred), or BMI. Weak positive correlations were observed with left ventricular fractional shortening, E/A ratio, and mitral annular velocity, but all coefficients were <0.2, indicating limited clinical relevance. No associations were found with right ventricular dimension or TRPG.
(A) Clinical characteristics of patients with idiopathic pleuroparenchymal fibroelastosis. (B) Comparison of electrocardiographic findings in patients with idiopathic pleuroparenchymal fibroelastosis and idiopathic pulmonary fibrosis.
| (A) Variables | (n=20) |
|---|---|
| Age, years | 74 [69.3, 76.8] |
| Sex, male | 12 (60) |
| Body mass index | 19.1 [17.4, 20.1] |
| Lower-lobe ILD, UIP pattern | 11 (55), 7 (35) |
| Flat chest index | 0.57 [0.51, 0.61] |
| PaO2, Torr | 87 [70.5, 99.3] |
| PaCO2, Torr | 50 [46,53] |
| (B) Variables | IPPFE(n=20) | IPF(n=18) | p value |
|---|---|---|---|
| PR, s | 0.15 [0.14, 0.17] | 0.17 [0.16, 0.19] | 0.013 |
| QRS, s | 0.10 [0.09, 0.10] | 0.10 [0.10, 0.11] | 0.241 |
| RR, s | 0.82 [0.74, 0.96] | 0.92 [0.75, 1.00] | 0.327 |
| QRS axis, degree | 70.5 [55.3, 77.3] | 32.5 [1.3, 63.5] | 0.007 |
| Heart rate, /min | 73.5 [62.5, 81] | 64.5 [59.5, 80] | 0.349 |
Data expressed as the median [IQR] or number (%). ILD: interstitial lung disease; UIP: usual interstitial pneumonia; IPPFE: idiopathic pleuroparenchymal fibroelastosis; IPF: idiopathic pulmonary fibrosis.
The present study found that the QRS axis on ECG in patients with IPPFE tended to be shifted more rightward than that in patients with IPF. However, the values did not reach the conventional threshold for the right-axis deviation (≥90°). Despite this inclination, no significant correlations were found between the QRS axis and either hilar elevation on chest CT or echocardiographic indicators of right-sided heart strain. IPPFE is characterized by upper-lobe-predominant fibrosis, pleural thickening, and platythorax, often accompanied by elevation of the pulmonary hilum.2 These anatomical changes may potentially alter the cardiac position and orientation. Representative findings of platythorax on chest CT and a rightward QRS axis shift on ECG are shown in Fig. 1A and B. Indeed, our findings confirmed that hilar elevation was significantly greater in IPPFE than in IPF, consistent with prior observations of structural remodeling of the thorax.7,8,12 However, the lack of correlation between hilar elevation and QRS axis suggests that hilar elevation alone is insufficient to explain the observed axis deviation. Rightward QRS axis deviation is typically associated with right ventricular hypertrophy, pulmonary hypertension, or right bundle branch block. In this study, although rightward axis deviation tended to be more frequent in the IPPFE group, echocardiographic indices did not reveal evidence of significant right ventricular overload or elevated pulmonary pressure. Taken together, these findings raise the possibility that the axis deviation in IPPFE may reflect cardiac rotation or displacement secondary to thoracic deformation rather than a functional cardiac disorder. Although the observed ECG findings are nonspecific, they may still hold diagnostic value in clinical practice. The shorter PR interval observed in IPPFE may also reflect subtle changes in cardiac orientation associated with thoracic deformation, although the clinical significance of this finding remains uncertain. In fact, we encountered cases in which ECG abnormalities, such as axis deviation, detected during routine health screening prompted further imaging and led to the diagnosis of IPPFE. These observations suggest that ECG axis deviation, even if nonspecific, may serve as an initial diagnostic clue, particularly in settings such as health screenings where radiological imaging is not routinely performed. Previous studies have reported pulmonary hypertension in approximately 20% of IPPFE patients and identified it as a poor prognostic factor.2,9,10 However, in our cohort, including the present cases, signs of pulmonary hypertension, such as elevated RVSP or reduced TAPSE, were generally absent, and ECG findings did not suggest hemodynamic compromise. This further supports the notion that ECG changes in IPPFE are primarily due to anatomical rather than physiological alterations.
Representative imaging and electrocardiographic findings in an 80-year-old man with idiopathic pleuroparenchymal fibroelastosis. (A) Axial chest computed tomography image showing marked platythorax (flat chest index, 0.49) with upper-lobe-predominant pleuroparenchymal fibrosis. (B) Twelve-lead electrocardiogram demonstrating right axis deviation (QRS axis, +105°) with occasional premature atrial contractions.
This study has several limitations. First, this was a retrospective single-center study with a relatively small sample size, which may have limited the statistical power of the correlation analyses. Second, potential confounding factors were not fully adjusted for. Third, pulmonary hypertension was assessed primarily by echocardiography rather than right heart catheterization; therefore, mild or subclinical pulmonary hypertension could not be completely excluded.
In conclusion, this study suggests a rightward shift of the QRS axis in IPPFE relative to IPF. Although nonspecific and not clearly associated with structural or functional metrics, the observed rightward axis shift may still reflect thoracic distortion. Nevertheless, ECG findings may serve as ancillary markers of thoracic deformation that may be subtle or overlooked on initial imaging, aiding the clinical recognition of IPPFE. Further studies with larger cohorts and longitudinal follow-up are warranted to elucidate the clinical relevance of axis deviation in the course of IPPFE.
Declaration of generative AI and AI-assisted technologies in the writing processArtificial intelligence was used exclusively for language editing and refinement of the manuscript, without influencing data collection, statistical analysis, or interpretation of the results.
Ethical considerationsThis study was conducted in accordance with the Declaration of Helsinki and applicable local regulations. The study protocol was approved by the institutional ethics committee (approval no. C25-05-004).
Informed consentThe requirement for informed consent was waived due to the retrospective nature of the study and the use of anonymized clinical data.
FundingThis research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
Authors’ contributionsAll authors contributed substantially to the study design, data collection, analysis, interpretation of the data, and preparation of the manuscript. All authors reviewed and approved the final version of the manuscript.
Conflicts of interestThe authors declare that they have no conflicts of interest that may be considered to influence directly or indirectly the content of the manuscript.
