Nailfold Capillaroscopy in PH

Pulmonary arterial hypertension (PAH) is a cause of precapillary pulmonary hypertension haemodynamically, where the disease process is caused by progressive narrowing of the arterioles of the pulmonary circuit. PH puts the right side of the heart under increasing strain, which causes it to fail and is ultimately fatal. PAH occurs in about 15% of patients with systemic sclerosis (SSc) and approximately 25% of cases of PAH in our centre are caused by SSc (SSc-PAH). It is the second leading cause of disease related death in SSc accounting for 26% of these deaths1.

Abnormalities of the small blood vessels are one of the main "drivers" of SSc. The poor blood supply/lack of oxygen interacts with fibrosis (scarring: overproduction of collagen) and causes damage to numerous organs (resulting for example in finger ulcers, skin thickening, kidney injury, lung fibrosis and gastro-intestinal involvement in addition to PAH).

It has been clearly established that these abnormalities are detectable in the nailbeds in SSc and form part of the diagnostic criteria for the disease 2,3. Moreover there is data that these abnormalities seem to correlate with disease severity in SSc, including with presence and severity of PAH 4.

There is limited evidence that blood vessel abnormalities in tissues outside of the lungs also occur in patients with so-called 'Idiopathic' Pulmonary Arterial Hypertension (IPAH), the other major cause of PAH and in chronic thromboembolic pulmonary hypertension (CTEPH) a disease where PH is caused by scarring from previous blood clots5 . However the blood vessel abnormalities described are more subtle than in SSc-PAH. It is not clear if they are related to issues with the pumping of the heart rather than an inherent issue with blood vessels outside of the lungs. It is not currently known if similar abnormalities exist in other forms of PH including PH related to lung disease (group 3 PH). Despite differences in the underlying pathology, all of these forms of PH are treated with drugs that open the vessels of the lungs (pulmonary vasodilators).

Our project aims to understand how patients with different forms of PH respond to pulmonary vasodilator therapy and how this differs between different types of pulmonary hypertension. The investigators intend to use the technique of nailfold capillaroscopy (examination of the smallest blood vessels - capillaries - of the nail bed with a microscope) to look at patients with different types of PH before and after treatment (or before and after treatment intensification).

It is known that nailfold capillary abnormalities occur very early in SSc6 but it is not certain that they can be reversed. In some diseases causing nailfold blood vessel abnormalities (e.g. dermatomyositis), it is known that the changes are reversible with treatment (steroids)7. There is some data suggesting the same is true in SSc. However this data comes from manual measurements, where due to the time consuming nature of such measurements, limited numbers of nailfolds are imaged or samples of the whole nailbed are taken. This is inherently unreliable. Recent advances in capillaroscopy mean that it is possible to quantify abnormalities automatically (in seconds), using low-cost USB microscopes, using automated analysis based on "machine learning" (ML) techniques. It is very possible that pulmonary vasodilators cause the small blood vessels in the fingers to 'remodel' in SSc i.e. become normal/ less abnormal again and the investigators wish to assess if this occurs. The investigators also wish to see if reported changes can be replicated in the nail beds of patients with IPAH/HPAH/CTEPH with this new technology and to see if these changes improve with the same treatments. The investigators also want to see if similar changes occur in another form of pulmonary hypertension (lung disease associated PH/group 3 disease) which might help us to understand if these changes are related to reduced cardiac output rather than an inherent disease of the blood vessels. The investigators want to compare how the groups of patients respond to these same treatments.

Finally the investigators want to see if the abnormalities detected correlate with conventional markers of disease severity and treatment response across the different groups of PH. This is important because if they did, NVC may be a useful, cheap, technically straightforward, non-irradiating biomarker of disease severity and treatment response.

This project seeks to better understand the pathophysiology of PH and to explore the effects of pulmonary vasodilator therapy on the condition. The project makes use of unique opportunities afforded by our position

• as the national referral centre for PH in Scotland with

• A highly enriched population of SSc patients commencing pulmonary vasodilator therapy (as standard of care for SSc-PAH)
• access to a diseased "control" population of patients with other forms of group 1 disease i.e. pulmonary arterial hypertension who receive the same diagnostic work up, therapies and clinical follow up as standard of care.
• Access to a diseased "control" population of patients with group 3 PH, who have pulmonary hypertension due to a different underlying pathology, and who again receive pulmonary vasodilators in some cases.
• with close links to the Scleroderma and Raynaud's Research Group at the University of Manchester. This affords us access to cutting edge AI/ML based automated image analysis that:

• allows rapid imaging of the nailbed allowing comparatively high throughput of participants
• Reproducible assessment and thus accurate evaluation of changes in the microvasculature of the digits pre and post treatment8

By studying the changes in the blood vessels in the nailbeds of patients with different forms of PH the investigators hope to better understand the mechanism of benefit of therapy, particularly in SSc, and to interrogate the relationship between microvasculopathy in the fingernail beds and markers of the severity of pulmonary vasculopathy causing their pulmonary hypertension.

This should advance patient care in a number of ways:

• Diagnosis of SSc:

a. NVC: i. Abnormalities form part of the diagnostic criteria for SSc. Use of NVC at a PH centre may detect patients meeting criteria for SSc-PAH that would otherwise have been labelled as "IPAH" thus ensuring accurate early diagnosis and appropriate holistic treatment of what is a multi-system disorder.

ii. Despite forming part of the ACR/EULAR 2013 diagnostic criteria for SSc and being part of the "Very Early Diagnosis of Systemic Sclerosis" (VEDOSS) criteria, uptake of NVC clinically is poor. Lack of confidence in interpretation of images is cited as a major barrier9. This project would build the evidence base for remote analysis, thus alleviating a barrier to uptake of the technology.

• Treatment of SSc:

i. There are a lack of reliable biomarkers of disease activity and treatment response in SSc. Development of non-invasive imaging techniques that can better assess disease activity and can predict disease response or progression (rather than detect the consequences of end organ damage after it has developed) would allow better risk stratification of patients and earlier and more targeted therapeutic intervention/ intensification where needed.

ii. If it can be demonstrated that microvascular abnormalities are reversible in patients treated with pulmonary vasodilator therapies (rather than that pulmonary vasodilators cause compensation through dilation of the remaining vessels) then:

• It would support trials exploring the use of pulmonary vasodilator therapies in SSc outside of their existing use cases (PAH, Raynaud's and Digital ulceration) for example in early disease to "Protect" the vasculature.
• It would provide mechanistic evidence that may support trials of newer pulmonary hypertension therapies (e.g. activin ligand traps) outside of their existing use case of SSc-PAH 3) Monitoring of PH: a. If it is demonstrated that these vascular abnormalities do occur in other forms of PH, and if it is shown that these changes correlate with conventional markers of disease severity then NVC might ultimately have a role as: i. A cheap, non-invasive, non-irradiating marker of disease severity or treatment response.

STUDY AIMS

The primary aim of this study is to:

• Assess whether NVC changes in SSc-PAH are reversible in patients treated with pulmonary vasodilator therapies.

The secondary aims of this study are to:

• Establish if NVC abnormalities are present in other forms of PH
• Establish if NVC measurements change over time in patients with other forms of PH treated with pulmonary vasodilator therapy
• Establish if NVC baseline measurements correlate with other markers of baseline disease severity in 4.1. SSc-PAH 4.2. Other forms of PH
• Establish if changes in NVC measurements whilst treated with PH therapies correlate with markers of disease response in 5.1. SSc-PAH 5.2. Other forms of PH

HYPOTHESES

• Nailfold capillaroscopic abnormalities in SSc-PAH reverse in patients treated with pulmonary vasodilators and these changes are greater than any change seen in other forms of PH
• Nailfold capillaroscopic abnormalities are present in other forms of PH at baseline
• Nailfold capillaroscopic abnormalities at baseline correlate with conventional markers of PH disease severity in SSc-PAH and other forms of PH
• Nailfold capillaroscopic changes in patients treated with pulmonary vasodilator therapy correlate with changes in conventional markers of disease severity/treatment response in SSc-PAH and other forms of PH.

METHODOLOGY

Patients will be recruited from the Scottish Pulmonary Vascular Unit at the Golden Jubilee National Hospital, Glasgow, Scotland.

Recruitment and Consent Potential inpatient participants will initially be identified by the CI by screening of their referral letters and clinical records (he is a member of the clinical team looking after patients). Identified patients will be approached on the afternoon of hospital admission by one of the research team who will explain what the study entails. If patients are amenable to inclusion, the research team will then provide a written participant information sheet (see separate document) and privacy notice (see separate document) and a 24-hour period will be given for potential participants to consider whether they would like to take part in the study. Following this consideration period, the research team will check whether the individual would like to participate. Potential participants who have indicated willingness to participate will then be approached by the investigator who will complete the consent process.

For outpatients, clinic lists and medical records will again be screened by the CI and patients who may be eligible will receive a brief description of the study with their clinic appointment letters when sent out. The description will contain a statement that the research team will discuss things further at their appointment and will provide contact details for patients to request further information prior to the appointment. On arrival at the clinic, the study will be further discussed with the patient by the research team. Potential participants who have indicated willingness to participate will then be approached by the investigator, if a clinical decision is made to escalate their medical therapy in clinic. The investigator will complete the consent process for anyone willing to take part.

Informed consent will be obtained by signing of the standard consent form which will then be signed by both the participant and the investigator.

Withdrawal of subjects

Participants have the right to withdraw from the trial at any point for any reason by contacting the study team and advising them of their decision to withdraw. Additionally, the investigators may withdraw participants from the study in the event of intercurrent illness, protocol violations or any other relevant reasons.

Patients who are withdrawn from the study will remain under standard clinical follow up. Research data gathered prior to the participant withdrawal may still be used for analysis and will be kept in pseudonymised form securely for 10 years following the conclusion of the study.

Participant Assessments (please see Study Flow chart below) First Inpatient Assessment (IP1, Baseline) During the inpatient diagnostic admission, routine investigations will be undertaken. These are part of standard clinical care.

• 2022 ERS/ESC Pulmonary Hypertension Guideline Diagnostic Group (as decided following multi-disciplinary discussion or consultant decision)
• World Health Organisation Functional Class (WHO FC) (decided by the admitting physician)
• History of digital ulcers/critical digital ischaemia
• Quality of life questionnaire (EmPHasis-10 questionnaire)
• Height, weight, BMI
• 6MWT (If able)
• Cardiopulmonary Exercise testing (where patients are able)
• TTE
• HRCT/CTPA
• CMR (Not performed in all cases)
• PFTs
• RHC
• Routine blood testing including Hb, CRP, NT-proBNP
• Medication history (current and in last 3 months), to include pulmonary vasodilators, immunosuppressant and immunomodulatory medications and other vasoactive medications.

Additional research investigations

• NVC
• RCS

Nailfold Capillaroscopy Methodology NVC measurements will then be obtained from participants at a suitable time over the next 48 hours if an inpatient (prior to right heart catheterisation and at a time that does not interfere with arrangements for other parts of routine clinical care). The scans will be performed using a Dino-Lite CapillaryScope (MEDL4N PRO) a UKCA marked medical device used for its intended purpose. The scans will be performed by the researcher in a dedicated, temperature controlled room. The process involves placing each fingernail bed sequentially under the specialised microscope. Photos spanning a full "panorama" of the nailbed will be obtained with adequate overlap (typically 4 images per nail bed). The nailbed images will then be transferred for remote analysis at the University of Manchester using further specialised software. The scanning process will take approximately 30 minutes.

The RCS is a questionnaire that will be supplied to the patient and can be completed at any point after enrolment and prior to right heart catheterisation.

First Outpatient Assessment (OP1, Baseline), and Return visits (IP2 or OP2 - 16 - 24 weeks later) During an outpatient clinic, routine investigations will be undertaken. These are part of standard clinical care.

• 2022 ERS/ESC Pulmonary Hypertension Guideline Diagnostic Group (as decided following multi-disciplinary discussion or consultant decision)
• World Health Organisation Functional Class (WHO FC) (decided by the attending physician)
• History of digital ulcers/critical digital ischaemia
• Quality of life questionnaire (EmPHasis-10 questionnaire)
• Height, weight, BMI
• 6MWT (If able)
• Routine blood testing including Hb, CRP, NT-proBNP
• Medication history (current and in last 3 months), to include pulmonary vasodilators, immunosuppressant and immunomodulatory medications and other vasoactive medications. This includes caffeine and nicotine consumption.

Additional research investigations

• NVC
• RCS NVC measurements will then be obtained from participants immediately after their clinic visit if an outpatient. All other aspects of the procedure are as detailed above. An RCS will again be obtained immediately prior to or after NVC.

Patient data will be collected in a pseudonymised database. Images obtained will be identified by the same pseudonymisation ID. These pseudonymised images will then be transferred for analysis at UoM. The data produced will then be returned to the investigator and added to the database.

Inclusion criteria

For inpatient enrolment:

• Suspected diagnosis of group 1,3 or 4 pulmonary hypertension undergoing inpatient assessment at nationally designated centre
• Age > 18 years

For follow up scanning of those enrolled as an inpatient:

• Confirmed diagnosis of pulmonary hypertension assessed at nationally designated centre fulfilling criteria for group 1, 3 or 4 disease
• Commencing PH targeted therapy, specifically one or more of: a phosphodiesterase 5 inhibitor (PDE5i), an ET receptor antagonist (ERA), parenteral prostanoid therapy, selexipag, riociguat, sotatercept.

For outpatient enrolment

• Confirmed diagnosis of pulmonary hypertension assessed at nationally designated centre fulfilling criteria for group 1, 3 or 4 disease
• Age > 18 years
• Escalating PH targeted therapy, specifically one or more of: a phosphodiesterase 5 inhibitor (PDE5i), an ET receptor antagonist (ERA), parenteral prostanoid therapy, selexipag, riociguat, sotatercept.

Target of > 25% of patients recruited at diagnosis and to have an SSc-spectrum disorder fulfilling either ACR/EULAR 2013 or VEDOSS (very early diagnosis of SSc) criteria.

Target of > 25% of patients recruited at diagnosis and to have non-SSc group 1 (PAH) diagnosis (as determined by national MDT decision).

Exclusion criteria

• Patients with confirmed group 2 or group 5 pulmonary hypertension
• Patients < 18 years of age
• Patients unable to participate in nailbed microscopy (through e.g. amputation, severe contractures or other musculoskeletal issues).
• (From follow up) Patients not being commenced on pulmonary vasodilator therapy at the point of diagnosis.
• Patients already on maximal PH therapy
• Patients lacking capacity to consent to participation
• Patients who are non-fluent English speakers, where suitable translation cannot be found within a time frame that makes the study feasible.
• Patients with a life expectancy < 4 months
• Patients who have consumed nicotine or caffeine within the last 4 - 6 hours
• Patients wearing nail polish / varnish/ extensions that preclude adequate nailbed visualisation.