Value of exercise right heart catheterization for differential diagnosis of dyspnoea in chronic thromboembolic pulmonary disease

Abstract Background and Purpose Chronic thromboembolic disease (CTED) refers to chronic thrombotic pulmonary vascular occlusion in the absence of pulmonary hypertension (PH) at rest but functional limitation attributable to incipient vasculopathy. Our aim is to evaluate the hemodynamic response to exercise in patients with suspected CTED without relevant resting PH. Methods We prospectively included symptomatic patients with persistent pulmonary thrombosis despite optimal anticoagulant therapy for a minimum of 3 months. Patients with left heart disease and abnormal lung function tests were excluded. Patients included had mean pulmonary arterial pressure (mPAP ) ≤25 mmHg, pulmonary vascular resistance (PVR) < 3 WU and pulmonary arterial wedge pressure (PAWP) ≤15 mmHg. Exercise right heart catheterization (RHC) was performed via supine cycle ergometry. Exercise precapillary PH was defined as mPAP/CO slope >3 mmHg/l/min and PAWP/CO slope 20mmHg & PVR > 2 WU) Results We studied 39 patients (mean age 52.7 ± 15.7 years, 36 % women): 12 of them met new resting PH criteria (mPAP > 20 mmHg & RVP > 2 WU) , and 27 had normal resting hemodynamic. Baseline characteristics are summarized in Table 1 and did not reveal differences between groups except for haemodynamic parameters. From the entire cohort, 20 patients developed exercise PH: 14 (36%) with a precapillary pattern, and in 6 (15.4%) patients, the abnormal response was described as an abnormal PAWP/CO relationship during exercise. Exercise precapillary PH was documented in 67% of patients with resting PH according to the new PH criteria versus 37% of those without resting PH (Figure 1). Conclusion The functional limitation appears to be attributable to exercise precapillary PH in 36 % of patients with CTED suspicion and absence of significant resting PH. Exercise RHC is a valuable tool for diagnosing CTED and detecting other causes of dyspnoea, such as diastolic dysfunction. New resting PH haemodynamic criteria predict a higher percentage of abnormal exercise response, but one-third of patients develop exPH despite normal haemodynamic at rest.