Chronic thromboembolic disease refers to the presence of chronic thrombotic pulmonary vascular thrombosis without pulmonary hypertension (PH) at rest but with exercise limitation after pulmonary embolism (PE). Our aim was to evaluate the hemodynamic response to exercise in these patients and its correlation with the values reached in cardiopulmonary exercise testing.

We included symptomatic patients with persistent pulmonary thrombosis after PE. We excluded patients with left heart disease or significant PH (mean pulmonary arterial pressure [mPAP] >25mmHg, pulmonary vascular resistance >3 WU, and pulmonary capillary wedge pressure [PCWP] >15mmHg). Cardiopulmonary exercise testing and exercise right heart catheterization were performed. Exercise-induced precapillary PH was defined as mPAP/CO slope >3 and PCWP/CO slope <2mmHg/l/min. The hemodynamic response and the values obtained in cardiopulmonary exercise testing were compared between patients with and without exercise-induced precapillary PH.

We studied 36 patients; 4 were excluded due to incomplete hemodynamic data. Out of the 32 patients analyzed; 3 developed a pathological increase in PCWP. Among the remaining 29 patients (mean age, 49.4±13.7 years, 34.5% women), 13 showed exercise-induced PH. Resting mPAP was higher in those who developed exercise-induced PH (23.3±5.4 vs 19.0±3.8mmHg; P=.012), although CO was similar in the 2 groups. Patients with exercise-induced PH exhibited data of ventilatory inefficiency with reduced values of end-tidal CO2 pressure at the anaerobic threshold (32.8±3.0 vs 36.2±3.3mmHg; P=.021) and a higher Ve/VCO2 slope (34.2±4.8 vs 30.7±5.0; P=.049).

Exercise limitation and ventilatory inefficiency could be attributable to exercise-induced precapillary PH in a subgroup of patients with persistent pulmonary thrombosis and dyspnea.