Q&A: Pulmonary arterial hypertension in NZ

PAH is one of the few conditions that truly bridges cardiology and respiratory medicine.

Pulmonary arterial hypertension directly affects the small blood vessels deep within the lungs.

Those vessels become narrowed and tighter, which makes it harder for blood to flow through them.

Over time, this increased resistance means the right side of the heart has to work much harder to pump blood through the lungs.

It is like putting your finger over the end of a hosepipe — the pressure builds up, and eventually the right side of the heart can weaken or fail.

Importantly, PAH is only one type of pulmonary hypertension.

Pulmonary hypertension is an umbrella term for high blood pressure in the lungs and is commonly seen in association with other conditions affecting the heart and lungs, where treatment should focus on the underlying condition.

PAH is rare.

Internationally, the incidence is around six cases per million adults per year.

It is unknown exactly how many New Zealanders have this condition, but probably a few hundred.

To address this gap in knowledge, myself and a group of clinicians are working on being able to contribute to the Pulmonary Hypertension Society of Australia and New Zealand (PHSANZ) Registry, hopefully including data from hospitals nationwide.

We don’t know our true numbers. We don’t know outcomes for Māori patients. We don’t know how our mortality compares internationally, so collecting this data is critical, not just for understanding how the disease affects patients in our country, but for advocating for better therapies.

Diagnosis is often delayed.

People may see many doctors before they finally receive a diagnosis.

The most common symptom is progressive breathlessness, which can initially be subtle but gradually becomes debilitating, even in young patients.

As the condition progresses, patients may develop light-headedness, chest pain and signs of right heart failure, such as fluid build-up in the legs.

PAH can affect people across the lifespan and may be associated with other conditions, including systemic sclerosis and certain congenital heart diseases.

Before modern treatments, median survival was estimated at around three years, but that was around 30 years ago, before we had effective therapies.

Today, prognosis has improved significantly, but outcomes vary and there are many unmet needs.

Some patients respond well to oral tablet therapies, while others require more aggressive treatments, including frequent nebulised therapy (up to seven times daily), or continuous intravenous (epoprostenol) infusion, delivered via a pump 24/7.

These treatments can be life-prolonging, but they come with a significant burden.

For advanced cases, lung transplantation is considered.

In most cases, only a lung transplant (not heart and lungs) is required, as the right ventricle can recover once lung resistance is removed.

There are a number of therapies that are not funded here and that we need to have access to in New Zealand.

PAH therapies have traditionally targeted three main biological pathways.

In New Zealand, funded medicines are available through Special Authority, meaning strict eligibility criteria apply.

However, several therapies used routinely internationally are not yet funded here.

There are three medicines routinely used in other countries such as the UK for at least the last seven years that are still not widely funded in New Zealand: Tadalafil (Adcirca), Riociguat (Adempas) and Selexipag (Uptravi).

Applications for Tadalafil and Riociguat are currently under assessment by Pharmac, but no final funding decision has been announced.

For medicines not listed under Special Authority, clinicians must apply via the Named Patient Pharmaceutical Assessment (NPPA) process — a time- consuming application that must be resubmitted every few months.

It’s extremely laborious and relies on clinician time and motivation.

It is not sustainable long-term.

One new drug, in particular, is generating a lot of global excitement: Sotatercept (Winrevair).

Sotatercept targets a newly identified fourth pathway in PAH and has shown potentially game-changing results overseas.

Patients have heard about it, and there is a great sense of hope around it.

However, access in New Zealand is extremely limited. Only a very small number of patients have obtained it via NPPA in exceptional circumstances.

It is not yet funded at scale here, or in Australia.

International evidence suggests Sotatercept may even allow some patients to come off continuous intravenous infusion therapy, replacing it with an injection given approximately every three weeks.

This drug would be transformative for so many patients living with PAH.

There is a clear medicine access gap.

Drugs we were using in the UK in 2019 are still not available here.

Geography and service distribution also create challenges unique to Australia and New Zealand.

A new Australia-New Zealand position statement is currently being finalised to address these regional realities.

The lack of registry data also weakens New Zealand’s position when advocating for funding.

If we can demonstrate our numbers and our outcomes, that becomes powerful evidence — it helps show what is needed.

This is a rare condition, but there are experienced clinicians who are passionate about looking after you.

We are absolutely motivated to give you the best treatments we can.

We will advocate on your behalf.

New drugs are on the horizon, and that gives me great hope.

However, regardless of what happens with funding or therapies, we will continue to support you the whole way through the journey, as well as we can.