Call for standardised pulmonary hypertension guidelines in ILD

Australian clinicians are calling for a standardised pulmonary hypertension screening protocol to expedite diagnosis and management in interstitial lung disease (ILD) patients, and they’ve already made some recommendations.

It comes after their retrospective study (linked here) revealed probable pulmonary hypertension had “substantial prevalence” among 162 Austin Health-assessed ILD patients, even on initial screening.

While ILD-related pulmonary hypertension is associated with poor prognosis, and early identification and intervention are guideline-advised, there are currently no standardised recommendations on how or when to screen for the condition, the Melbourne-based respiratory physician and cardiologist authors wrote in the Internal Medicine Journal.

Developing and implementing such recommendations could be key to improving survival outcomes in these patients, they suggested.

To capture some of Austin Health’s pulmonary hypertension assessment practices in idiopathic pulmonary fibrosis or connective tissue disease-associated ILD, they audited the centre’s ILD registry, established in 2015.

They found 147 patients were tested for pulmonary hypertension, with 65% undergoing transthoracic echocardiography (TTE) at least once over a median 30-month follow-up period.

A third of these had a “high probability of pulmonary hypertension, defined as right ventricular systolic pressure > 40 mmHg + right atrial pressure and/or right ventricular dysfunction”, and 45 patients met the criteria at latest TTE.

Further, 47 had elevated serum N-terminal pro-brain natriuretic peptide levels during the first year.

Despite all this, only 14 had right heart catheterisation, needed to definitively diagnose pulmonary hypertension, the authors found. (Ten were confirmed positive for pulmonary hypertension.)

“There are no current guidelines for pulmonary hypertension screening in the ILD population,” the authors wrote.

The need for standardised guidelines

“The 2015 European Respiratory Society/European Society of Cardiology guidelines suggest referral to an expert centre for the management of pulmonary hypertension-ILD once the diagnosis is suspected.

“While different non-invasive screening algorithms have been proposed to assess probability of pulmonary hypertension and to identify candidates for right heart catheterisation in patients with connective tissue disease, patients with ILD, defined as forced volume capacity less than 60–85% predicted or by the presence of fibrosis on CT chest imaging, were excluded in the development of these algorithms,” the authors wrote.

An equation using resting oxygen saturation, forced volume capacity and diffusing capacity for carbon monoxide (DLCO); and parameters such as total lung capacity/DLCO and six-minute walk distance appear promising non-invasive predictors of pulmonary hypertension in ILD patients, they noted.

“Further work using clinical data from a large cohort of patients with a broad range of ILD subtypes and incorporating NTpro-BNP is required to develop a risk stratification model to guide evaluation and monitoring of pulmonary in the ILD population.”

Ultimately, a pulmonary hypertension-screening process in ILD “should include measurement of NT-proBNP, TTE, lung function parameters, and a six-minute walk test, both at baseline and serial intervals”, they suggested.

Developing and implementing a routine, standardised protocol “will expedite early detection of this important complication, facilitating prognostication, management, and delivery of comprehensive care, including novel therapies as they emerge”.

Currently, there are no guideline-recommended drugs for pulmonary hypertension in ILD, however, some studies have seen physiological benefits with phosphodiesterase-5 inhibitor sildenafil, and the inhaled prostanoid treprostinil has led to short-term improvements in exercise capacity and NT-proBNP levels in a recent, randomised trial.

Meanwhile, selective vasodilator agents, such as endothelin receptor agonists and soluble guanylate cyclase activators have produced adverse clinical results, the authors wrote.

Nevertheless, the reduced functional status and quality of life, greater oxygen requirement and increased mortality-risk associated with pulmonary hypertension-complicated ILD create a “compelling case” for developing a “standardised algorithm for early detection of at-risk patients who may benefit from early referral to an expert centre”, the authors concluded.

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