Pulmonary Hypertension: Screening and Evaluation in Scleroderma

Michael York; Harrison W. Farber

Disclosures

Curr Opin Rheumatol. 2011;23(6):536-544. 

In This Article

Abstract and Introduction

Abstract

Purpose of review The review provides an update of the epidemiology, pathogenesis, risk factors, screening and treatment of pulmonary arterial hypertension in systemic sclerosis.
Recent findings Several recent studies have investigated the utility of several noninvasive screening methods and the propagation of new treatments promise the clinician better outcomes than the current median survival time of 1 year for patients with scleroderma-related pulmonary arterial hypertension.
Summary Pulmonary hypertension is a frequent cause of morbidity and mortality in patients with systemic sclerosis. This review discusses the recent changes in the classification of pulmonary hypertension, especially the significance for the rheumatologist. A high clinical suspicion should be maintained, even in early scleroderma. Despite progress in echocardiography and biomarkers, right heart catheterization remains the only test that can diagnose pulmonary hypertension and differentiate pulmonary veno-occlusive disease from pulmonary arterial hypertension. The differentiation of these causes of pulmonary hypertension in the scleroderma patient is essential because the initiation of pulmonary vasodilators in veno-occlusive disease often leads to increased mortality. The role of screening with serum biomarkers and noninvasive testing remains controversial, and in this review we discuss the controversies and new recommendations in detail.

Introduction

Pulmonary arterial hypertension (PAH) is primarily a disease of pulmonary vascular resistance (PVR) caused by proliferation and contraction of vascular smooth muscle cells. PAH is a frequent complication of systemic sclerosis (SSc) observed with a prevalence of 8–12%[1–3] due to a proliferative arterial pulmonary microangiopathy. A recent meta-analysis of more than 3500 SSc patients demonstrated a prevalence of PAH, based on right heart catheterization (RHC) of slightly less than 10%.[4] In order to diagnose PAH, it is necessary to establish the appropriate cardiopulmonary hemodynamics, mean pulmonary artery pressure (mPAP) at least 25 mmHg, pulmonary capillary wedge pressure or left-ventricular end-diastolic pressure 15 mmHg or less, and a PVR at least 240 dyn/cm−5 (3 Wood units); currently, the only available method for detecting and assessing these and other important cardiopulmonary hemodynamic parameters (i.e. cardiac output) is RHC; thus, RHC should be performed in all cases in which PAH is suspected. It not only confirms the presence of pulmonary hypertension and enables the establishment of a specific diagnosis of PAH, but it also eliminates other cardiac causes and assesses the degree of right heart dysfunction.[5]

Within the past two decades, pulmonary fibrosis and PAH have become the leading causes of morbidity and mortality in SSc patients.[6] The estimated 3-year survival among patients with PAH associated with SSc is approximately 50%.[7] The development of PAH in SSc must be differentiated from pulmonary hypertension associated with pulmonary fibrosis. Distinguishing PAH from pulmonary hypertension associated with pulmonary fibrosis is not always easy, especially since some patients can have both pulmonary fibrosis and a true pulmonary vasculopathy (PAH). However, if lung volumes [forced vital capacity (FVC) and/or total lung capacity (TLC)] are less than 60% of the predicted value and mPAP is less than 35 mmHg at rest, pulmonary hypertension is deemed more likely related to pulmonary fibrosis.[8] When lung volumes are above 70% of the predicted value, the pulmonary hypertension is considered more likely to be PAH. When lung volumes are between 60 and 70% of the predicted value, the diagnosis becomes more difficult; however, if mPAP is greater than 35 mmHg, the pulmonary hypertension is considered out of proportion (or reactive) and most probably reflects a true pulmonary artery microangiopathy. Nevertheless, as noted, pulmonary hypertension due to hypoxemia and PAH may coexist in SSc patients. In this review, we will mainly focus on PAH.

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