Progressive Right Ventricular Dysfunction in Patients With Pulmonary Arterial Hypertension Responding to Therapy
What is the relationship between changes in pulmonary vascular resistance (PVR) and right ventricular ejection fraction (RVEF) and survival in patients with pulmonary arterial hypertension (PAH) under PAH-targeted therapies?
A total of 110 patients with incident PAH (congenital heart disease excluded) underwent baseline right heart catheterization, cardiac magnetic resonance imaging (MRI), and 6-minute walk testing. These measurements were repeated in 76 patients after 12 months of therapy. Survival was estimated from time of enrollment to cardiopulmonary death or lung transplant. Noncardiopulmonary deaths were considered censored at time of death. A change in RVEF by cardiac MRI was considered as an increase or decrease of 3% or greater, and in PVR by 15 dyne•s•cm–5.
Median follow-up was 59 months (interquartile range, 30-74 months). Mean baseline hemodynamic values were: mean pulmonary artery pressure 49 mm Hg, mean right artery pressure 7 mm Hg, cardiac output 5.1 L/min, and PVR 745 dyne•s•cm–5. There was no difference in baseline variables for those who did and did not undergo the 1-year repeated studies. In the 76 patients with follow-up, mean age was 50 years, 83% were female, 78% were idiopathic, 14% related to connective tissue disease, and 52% were New York Heart Association (NYHA) class III/IV. Medical treatment comprised prostacyclins (11%), endothelin receptor antagonists (34%), and phosphodiesterase-5 inhibitors (13%), either alone or in various combinations (41%). Two patients underwent lung transplantation, 13 patients died during the first year, and 17 patients died in the subsequent follow-up of 47 months. Baseline RVEF (hazard ratio [HR], 0.938; p = 0.001) and PVR (HR, 1.001; p = 0.031) were predictors of mortality. During the first 12 months, changes in PVR were moderately correlated with changes in RVEF (R = 0.330; p = 0.005). Changes in RVEF (HR, 0.929; p = 0.014) were associated with survival, but changes in PVR (HR, 1.001; p = 0.920) were not. In 68% of patients, PVR decreased after medical therapy; 25% of those patients with decreased PVR showed a deterioration of RV function and had a poor prognosis. At 1-year follow-up, there were no differences in changes in PVR or RVEF by PAH treatments alone or in combination.
After PAH-targeted therapy, RV function can deteriorate despite a reduction in PVR. Loss of RV function is associated with a poor outcome, irrespective of any changes in PVR.
The study cohort is characteristic of incident PAH reports, but for the relatively high percent of NYHA class I-II patients, and higher 6-minute walk distance and cardiac index. It is not surprising that the RVEF as measured by cardiac MRI is a better predictor than PVR for survival. Further studies are necessary to determine whether cardiac MRI parameters including RVEF should be used to determine choice of PAH-specific treatments and timing for transplant.
Clinical Topics: Congenital Heart Disease and Pediatric Cardiology, Heart Failure and Cardiomyopathies, Noninvasive Imaging, Pulmonary Hypertension and Venous Thromboembolism, Valvular Heart Disease, Congenital Heart Disease, CHD and Pediatrics and Imaging, CHD and Pediatrics and Quality Improvement, Acute Heart Failure, Pulmonary Hypertension, Magnetic Resonance Imaging
Keywords: Follow-Up Studies, Heart Defects, Congenital, Cardiac Catheterization, Electrocardiography, New York, Magnetic Resonance Imaging, Ventricular Dysfunction, Right, Hemodynamics, Heart Diseases, Prognosis, Pulmonary Valve Insufficiency, Heart Failure, Hypertension, Pulmonary, Vascular Resistance
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