UMIN-CTR Clinical Trial

Public title

Noninvasive Assessment of Pulmonary Vascular Resistance Using Right-Ventricular IRT in Idiopathic Pulmonary Fibrosis

Acronym

IPF-IRT Study

Scientific Title

Retrospective Observational Study on the Association Between Right-Ventricular Isovolumetric Relaxation Time and Pulmonary Vascular Resistance in Idiopathic Pulmonary Fibrosis

Scientific Title:Acronym

IPF-IRT Study

Region

Japan

Condition

Idiopathic Pulmonary Fibrosis

Classification by specialty

Pneumology

Classification by malignancy

Others

Genomic information

NO

Narrative objectives1

To determine whether right ventricular isovolumetric relaxation time (IRT) serves as a useful noninvasive marker of pulmonary vascular resistance (PVR) and pulmonary vascular resistance index (PVRI) in patients with idiopathic pulmonary fibrosis (IPF).

Basic objectives2

Others

Basic objectives -Others

This is a two-center retrospective observational study designed primarily to evaluate the association between right ventricular isovolumetric relaxation time (IRT) and invasively measured pulmonary vascular resistance (PVR) in patients with idiopathic pulmonary fibrosis (IPF). Using two institutional cohorts, the study evaluates the reproducibility of the association between IRT and PVR, examines its association with pulmonary vascular resistance index (PVRI), and assesses the potential utility of IRT as a noninvasive marker reflecting pulmonary vascular load.

Trial characteristics_1

Exploratory

Trial characteristics_2

Explanatory

Developmental phase

Not applicable

Primary outcomes

Correlation coefficient between right ventricular isovolumetric relaxation time (IRT) and pulmonary vascular resistance (PVR) obtained from transthoracic echocardiography and right heart catheterization performed during the same hospitalization period.

Key secondary outcomes

Correlation between IRT and pulmonary vascular resistance index (PVRI).
Correlation between IRT and mean pulmonary arterial pressure (mPAP).
Discriminative performance of IRT for identifying PVR greater than 2 Wood units, assessed using receiver operating characteristic (ROC) curve analysis.
Validation of the IRT cutoff derived in the derivation cohort by applying the fixed cutoff to the independent validation cohort and evaluating its sensitivity and specificity.
Comparison of IRT between patients with and without pulmonary hypertension (PH).
Association between IRT and right ventricular-pulmonary arterial coupling indices (e.g., TAPSE/sPAP).
Correlation between pulmonary artery acceleration time (PAAcT) and PVRI.
Correlations of pulmonary function parameters (FVC and DLCO) with PVR and PVRI.

Study type

Observational

Basic design

Randomization

Randomization unit

Blinding

Control

Stratification

Dynamic allocation

Institution consideration

Blocking

Concealment

No. of arms

Purpose of intervention

Type of intervention

Interventions/Control_1

Interventions/Control_2

Interventions/Control_3

Interventions/Control_4

Interventions/Control_5

Interventions/Control_6

Interventions/Control_7

Interventions/Control_8

Interventions/Control_9

Interventions/Control_10

Age-lower limit

18

years-old

<=

Age-upper limit

Not applicable

Gender

Male and Female

Key inclusion criteria

Age at least 18 years
Diagnosis of idiopathic pulmonary fibrosis (IPF) based on ATS/ERS/JRS/ALAT guidelines
Transthoracic echocardiography and right heart catheterization performed during the same hospitalization under stable clinical conditions
No acute exacerbation, clinically apparent infection, or hospitalization for deterioration within the preceding 4 to 8 weeks
If antifibrotic therapy is used, the dose must be stable for at least 4 weeks before evaluation
Complete hemodynamic data including mPAP, PAWP, and cardiac output
Doppler waveforms adequate for assessment of IRT and PAAcT

Patients receiving long-term oxygen therapy at the minimum clinically required flow rate for hypoxemia associated with IPF may be included. Patients receiving the minimum clinically required dose of diuretics for management of pulmonary hypertension associated with IPF may also be included, provided that treatment has been stable for at least 4 weeks before evaluation.

Key exclusion criteria

Left heart disease, including LVEF less than 50 percent, moderate or greater valvular disease, hypertrophic cardiomyopathy, or restrictive cardiomyopathy
PAWP greater than 15 mmHg
Interstitial lung disease other than IPF
Chronic thromboembolic pulmonary disease or chronic thromboembolic pulmonary hypertension
Atrial fibrillation or other significant arrhythmias that interfere with IRT assessment
Inadequate acoustic windows for Doppler evaluation
Pulmonary hypertension specific therapy initiated before evaluation
Missing essential echocardiographic or hemodynamic data
Clinically significant combined pulmonary fibrosis and emphysema was excluded, whereas mild emphysema involving less than 10 percent of the lung was permitted.

Target sample size

276

Name of lead principal investigator

1st name	Yosuke
Middle name
Last name	Tanaka

Organization

Nippon Medical School Hospital

Division name

Department of Respiratory Medicine

Zip code

113-8603

Address

1-1-5 Sendagi, Bunkyo-ku, Tokyo 113-8603, Japan

TEL

03-3822-2131

Email

yosuke-t@nms.ac.jp

Name of contact person

1st name	Yosuke
Middle name
Last name	Tanaka

Organization

Nippon Medical School Hospital

Division name

Department of Respiratory Medicine

Zip code

113-8603

Address

1-1-5 Sendagi, Bunkyo-ku, Tokyo 113-8603, Japan

TEL

03-3822-2131

Homepage URL

Email

yosuke-t@nms.ac.jp

Institute

Nippon Medical School

Institute

Department

Personal name

Yosuke Tanaka

Organization

Nippon Medical School

Organization

Division

Category of Funding Organization

Self funding

Nationality of Funding Organization

Co-sponsor

Nippon Medical School Chiba Hokusoh Hospital

Name of secondary funder(s)

Organization

Institutional Review Board of Nippon Medical School Hospital

Address

1-1-5 Sendagi, Bunkyo-ku, Tokyo 113-8603, Japan

Tel

03-3822-2131

Email

nms_fuzokurinri@nms.ac.jp

Secondary IDs

NO

Study ID_1

Org. issuing International ID_1

Study ID_2

Org. issuing International ID_2

IND to MHLW

Institutions

日本医科大学付属病院（東京都）、
日本医科大学千葉北総病院（千葉県）

Date of disclosure of the study information

2026

Year

01

Month

10

Day

URL releasing protocol

Publication of results

Unpublished

URL related to results and publications

Number of participants that the trial has enrolled

276

Results

Results date posted

Results Delayed

Results Delay Reason

Date of the first journal publication of results

Baseline Characteristics

Participant flow

Adverse events

Outcome measures

Plan to share IPD

Deidentified individual participant data may be made available upon reasonable request to the corresponding investigator, subject to ethical and institutional approval.

IPD sharing Plan description

Requests for deidentified individual participant data will be considered in accordance with participant privacy requirements, research ethics, and institutional policies. Data availability will depend on the purpose of the request, ethical appropriateness, and approval by the participating institutions.

Recruitment status

No longer recruiting

Date of protocol fixation

2015

Year

03

Month

01

Day

Date of IRB

2020

Year

10

Month

01

Day

Anticipated trial start date

2015

Year

04

Month

01

Day

Last follow-up date

2026

Year

09

Month

30

Day

Date of closure to data entry

2026

Year

10

Month

15

Day

Date trial data considered complete

2026

Year

10

Month

31

Day

Date analysis concluded

2026

Year

11

Month

15

Day

Other related information

This two-center retrospective observational study uses routine clinical data obtained at Nippon Medical School Hospital and Nippon Medical School Chiba Hokusoh Hospital from April 1, 2015 to September 30, 2026. Patients from the former constitute the derivation cohort and those from the latter the validation cohort, with the same eligibility criteria applied at both centers. The primary analysis evaluates the association between right ventricular isovolumetric relaxation time (IRT) and pulmonary vascular resistance (PVR) and its reproducibility across the two cohorts. Secondary analyses include the association between IRT and pulmonary vascular resistance index (PVRI), discrimination of PVR greater than 2 Wood units, and validation of the derivation-cohort IRT cutoff.

The initial analysis included 206 patients, comprising 121 in the derivation cohort and 85 in the validation cohort. After extension of the study period using the same eligibility criteria, the final dataset comprised 276 patients, with 140 and 136 patients, respectively. No additional patients will be included. The target sample size of 180 entered at initial registration was an input error and has been corrected to 276.

The study is conducted under ethical approval B-2020-175 using existing clinical data and an opt-out process. The actual study protocol was developed in 2025. The UMIN protocol fixation date of March 1, 2015 cannot be modified after registration and therefore remains unchanged. The end of the patient inclusion period was updated to September 30, 2026.

In the updated analysis plan, PVR was designated as the primary hemodynamic outcome to align the primary continuous analysis with the clinically established PVR threshold, while PVRI was retained as a secondary outcome. This does not alter the fundamental study objective of evaluating whether IRT reflects pulmonary vascular load in IPF.

Registered date

2025

Year

12

Month

05

Day

Last modified on

2026

Year

11

Month

03

Day

Link to view the page

Value
https://center6.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000068591