Page 43 - Assessing right ventricular function and the pulmonary circulation in pulmonary hypertension Onno Anthonius Spruijt

Introduction
Pulmonary arterial hypertension (PAH) is a rare condition caused by the progressive narrowing of the small pulmonary arteries, leading to increased pulmonary vascular resistance and right-sided heart failure [1]. Despite advances in therapy, the mortality remains high, approaching 30% to 50% at 5 years in symptomatic patients [1, 2]. In recent years, right ventricular (RV) function has emerged as one of the strongest predictors of outcome in PAH [3]. Hemodynamic studies have highlighted the prognostic importance of elevated right atrial (RA) pressure and decreased cardiac output, whereas imaging studies have highlighted the importance of RV remodeling and systolic function [2, 4-6]. Moreover, recent scores, such as the REVEAL (Registry to Evaluate Early and Long-Term PAH Disease Management) score, have integrated several of the clinical and functional parameters [2].
To date, only a few studies have investigated whether RA size or function has incremental value to RV function in predicting outcome in PAH. The importance of RA size in PAH was first suggested by Bustamente-Labarta et al. [7] in their series of 25 patients. In a larger study in patients with PAH (n=81), Raymond et al. [8] found that there was a trend for an independent association between RA area index (p=0.106) and the composite endpoint of death or transplantation. To our knowledge, no study has of yet also investigated the prognostic value of RA function measured by active and passive emptying fractions (RAEF) in PAH.
For our study, we first hypothesized that measures of RA size or function would be independently associated with event-free survival in PAH. We further hypothesized that a simple score combining quantitative measures of right heart size or function would provide good discrimination of outcome in PAH.
Methods
Study design
Our study included a derivation cohort at Stanford University, followed by a validation cohort at the VU University Medical Center. After ethics committee approval, consecutive adult patients followed at Stanford University between January 1999 and January 2009 with a confirmed diagnosis of idiopathic or drug and toxin PAH were considered for inclusion in the study. The diagnosis of PAH was on the basis of the standard definition of mean pulmonary arterial pressure ≥25mmHg and pulmonary artery wedge pressure ≤15mmHg [9]. We excluded patients for whom an echocardiogram was not available and patients with evidence of atrial fibrillation at baseline, left
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