Hemodynamic Response to Treatment and Outcomes in Pulmonary Hypertension Associated With Interstitial Lung Disease Versus Pulmonary Arterial Hypertension in Systemic Sclerosis: Data From a Study Identifying Prognostic Factors in Pulmonary Hypertension Associated With Interstitial Lung Disease

Patients with systemic sclerosis and both pulmonary hypertension and interstitial lung disease (SSc-PH-ILD) generally carry a worse prognosis than patients with SSc and pulmonary arterial hypertension (SSc-PAH) without ILD. There is no evidence of the efficacy of PAH therapies in SSc-PH-ILD. We undertook this study to compare survival of and response to treatment in patients with SSc-PH-ILD and those with SSc-PAH.We analyzed 128 patients (66 with SSc-PH-ILD and 62 with SSc-PAH) from 15 centers, in whom PH was diagnosed by right-sided heart catheterization; they were prospectively included in the PH registry. All patients received PAH-specific therapy. Computed tomography of the chest was used to confirm or exclude ILD.At baseline, patients with SSc-PH-ILD had less severe hemodynamic impairment than those with SSc-PAH (pulmonary vascular resistance 5.7 Wood units versus 8.7 Wood units; P = 0.0005) and lower diffusing capacity for carbon monoxide (median 25% [interquartile range (IQR) 18%, 35%] versus 40% [IQR 31%, 51%]; P = 0.0005). Additionally, patients with SSc-PH-ILD had increased mortality (8.1% at 1 year, 21.2% at 2 years, and 41.5% at 3 years) compared to those with SSc-PAH (4.1%, 8.7%, and 21.4%, respectively; P = 0.04). Upon treatment with PAH-targeted therapy, no improvement in the 6-minute walk distance was observed in either group. Improvement in the World Health Organization functional class was observed less frequently in patients with SSc-ILD-PH compared to those with SSc-PAH (13.6% versus 33.3%; P = 0.02). Hemodynamics improved similarly in both groups.ILD confers a worse prognosis to SSc-PH. Response to PAH-specific therapy is clinically poor in SSc-PH-ILD but was not found to be hemodynamically different from the response observed in SSc-PAH.