Treatment of pulmonary hypertension in interstitial lung disease: do not throw out the baby with the bath water

Abstract

Pulmonary hypertension (PH), group III of the international aetiological classification [1], is a frequent and severe complication of interstitial lung diseases (ILDs), especially idiopathic pulmonary fibrosis (IPF), the syndrome of combined pulmonary fibrosis and emphysema, ILD associated with connective tissue disease, sarcoidosis, pulmonary Langerhans cell histiocytosis and, rarely, other ILDs [2–6]. Although its prevalence varies widely between these conditions, PH, when present, dramatically impacts morbidity and survival. Despite recent progress with pirfenidone and nintedanib, which reduce the rate of decline in lung function in patients with mild-to-moderate disease [7, 8], management of IPF remains largely supportive, with a relentless progression to respiratory failure and death after a median of only 3 years from the time of diagnosis. Precapillary PH is common in advanced IPF, with a prevalence of 32–46% [9–12] at right heart catheterisation (RHC) at the time of evaluation for lung transplantation. The haemodynamic severity of PH in this context is usually mild, although 2–10% of patients have severe PH with a mean pulmonary artery pressure (mPAP) greater than 35–40 mmHg [9, 10]. PH is associated with increased dyspnoea, decreased exercise capacity as measured by the 6-min walk distance (6MWD) and the peak oxygen uptake at cardiopulmonary exercise testing [9, 13, 14], lower diffusing capacity of the lung for carbon monoxide ( D LCO), greater oxygen requirements and reduced survival [2, 9]. In one study, the 1-year mortality of patients with IPF and associated PH at RHC was 28% versus only 5.5% in those without PH [9]. In subjects with moderate functional impairment, the prevalence of PH is lower and varies depending upon the procedures used. In a recent series of 101 patients who underwent …