Right ventricular (RV) function is a major determinant of exercise intolerance and outcome in idiopathic pulmonary arterial hypertension. The aim of the study was to evaluate the incremental prognostic value of echocardiography of the right ventricle and cardiopulmonary exercise testing (CPET) on long-term prognosis in these patients.
One hundred and thirty treatment-naïve patients with idiopathic pulmonary arterial hypertension were enrolled and prospectively followed. Clinical worsening (CW) was defined by a reduction in 6-min walk distance plus an increase in functional class, or nonelective hospitalization for PAH, or death. Baseline evaluation included clinical, hemodynamic, echocardiographic, and CPET variables. Cox regression modeling with c-statistic and bootstrapping validation methods were done.
During a mean period of 528 ± 304 days, 54 patients experienced CW (53%). Among demographic, clinical, and hemodynamic variables at catheterization, functional class and cardiac index were independent predictors of CW (model 1). With addition of echocardiographic and CPET variables (model 2), peak O2 pulse (peak o2/heart rate) and RV fractional area change (RVFAC) independently improved the power of the prognostic model (area under the curve, 0.81 vs 0.66, respectively; P = .005). Patients with low RVFAC and low O2 pulse (low RVFAC + low O2 pulse) and high RVFAC + low O2 pulse showed a 99.8 and 29.4 increase in the hazard ratio, respectively (relative risk, 41.1 and 25.3, respectively), compared with high RVFAC + high O2 pulse (P = .0001).
Echocardiography combined with CPET provides relevant clinical and prognostic information. A combination of low RVFAC and low O2 pulse identifies patients at a particularly high risk of clinical deterioration.