Right Ventricular Load at Exercise Is a Cause of Persistent Exercise Limitation in Patients With Normal Resting Pulmonary Vascular Resistance After Pulmonary Endarterectomy

Background Pulmonary endarterectomy (PEA) provides a potential cure for patients with chronic thromboembolic pulmonary hypertension (CTEPH). However, successfully operated patients can continue to suffer from a limitation of exercise capacity, despite normalization of pulmonary vascular resistance (PVR). The purpose of the present study was to explore the cardiopulmonary exercise test (CPET) profile and the pulmonary hemodynamic response to exercise in these patients. Methods Thirteen successfully operated patients with CTEPH and persistent dyspnea and control subjects underwent a CPET and a right-sided heart catheterization at rest and during exercise. Results The CPET profile of the patients was characterized by mild hyperventilation and decreased peak oxygen uptake (o 2 ). While there were no differences in resting hemodynamics between patients and control subjects, PVR was higher in the patients after 10 min of exercise (111 ± 46 dynes/s/cm 5 vs 71 ± 42 dynes/s/cm 5 , P = .04), and pulmonary arterial compliance (Ca) was lower (5.5 ± 2.3 mL/mm Hg vs 8.1 ± 3.5 mL/mm Hg, P = .048). Ca under exercise correlated with peak o 2 in the patients ( R 2 = 0.825, P = .022). Conclusions After successful PEA, patients with persistent exertional dyspnea display an abnormal pulmonary hemodynamic response to exercise, characterized by increased PVR and decreased Ca. Decreased Ca under exercise is a strong predictor of limited exercise capacity in these patients.