FROM CHEST
Adding echocardiography and cardiopulmonary exercise testing to baseline right heart catheterization improves prognostic accuracy in idiopathic pulmonary arterial hypertension, according to a prospective Italian study of 102 newly diagnosed patients.
A combination of low right ventricular fractional area change (RVFAC) on echocardiography and low oxygen pulse on cardiopulmonary exercise testing (CPET) “identifies patients at a particularly high risk of clinical deterioration.” Both are markers of right ventricular (RV) function, which is a major determinant of outcome in idiopathic pulmonary arterial hypertension [iPAH], said investigators led by Roberto Badagliacca, MD, of the Sapienza University of Rome (Chest. 2016 Aug 20. pii: S0012-3692(16)56052-8. doi: 10.1016/j.chest.2016.07.036).
PAH diagnosis requires right heart catheterization, and findings have long been known to predict PAH outcome. However, catheterization allows only “an indirect description of RV function,” the investigators said. Recent studies have shown that RV echocardiography and CPET improve the accuracy of heart failure prognosis, so the investigators wanted to see if they’d do the same for PAH.
Their results “strongly suggest that noninvasive measurements related to RV function obtained by combining resting echocardiography and CPET are of added value to right heart catheterization in the assessment of severity and prognostication of PAH,” they said.
During a mean follow-up of 528 days, 54 patients (53%) had clinical worsening, defined as a 15% reduction in 6-minute walk distance from baseline plus a worsening of functional class, nonelective PAH hospitalization, or death.
Baseline functional class and cardiac index proved to be independent predictors of clinical worsening. Adding echocardiographic and CPET variables independently improved prognostic power (area under the curve, 0.81 vs. 0.66; P = .005).
Compared with patients with high RVFAC and high oxygen pulse at baseline, patients with low RVFAC and low oxygen pulse had a 99.8 increase in the hazard ratio for clinical worsening, and those with high RVFAC and low oxygen had a 29.4 increase (P = .0001).
Several echocardiographic variables for RV function have previously been reported as independent predictors of PAH outcome. “The new finding here is that RVFAC outperformed other echocardiographic indices of systolic function,” the investigators wrote.
“As for peak oxygen pulse, this variable is thought to assess maximum [stroke volume],” assumed to be determined by RV function; MRI-determined stroke volume has been previously shown to be an important predictor of survival in PAH,” they said.
The mean age in the study was 52 years, mean functional class was 2.7, and mean 6-minute walk distance was 430 m; 62 subjects were women. The most relevant comorbidities were diabetes in 5 patients, hypercholesterolemia in 10, thyroid diseases in 6, and clinical depression in 7. Patients with severe tricuspid regurgitation or exercise-induced opening of the foramen ovale were excluded. However, a reanalysis including patients with exercise-induced right to left shunting showed the same independent predictors of PAH outcome.
After diagnosis, patients were treated with endothelin receptor antagonists, phosphodiesterase-5 inhibitors, and prostanoids.
Dr. Badagliacca reported speaker and adviser fees from United Therapeutics, Dompe, GSK, and Bayer. His colleagues reported no conflicts of interest.
