Incidence of chronic thromboembolic pulmonary hypertension after a first episode of pulmonary embolism.

Study Objective: To assess the incidence of chronic thromboembolic pulmonary hypertension (CTPH) after the first episode of objectively confirmed pulmonary embolism (PE).

Design: Prospective cohort study in 12 Italian medical centers.

Patients: Consecutive patients treated with oral anticoagulants for the first episode of PE, either idiopathic or associated with temporary risk factors, were followed up for at least 3 years. Patients were excluded from the study if they had a known persistent risk factor for venous thromboembolism (VTE).

Interventions: At the follow-up visits, patients were evaluated for persistent dyspnea, either at rest or on exertion. All patients who were referred with dyspnea were assessed by transthoracic echocardiography, with evaluation of the systolic and mean pulmonary artery pressures. Patients with evidence of pulmonary hypertension on echocardiography underwent perfusion lung scans and pulmonary angiography to confirm the diagnosis of CTPH.

Results: Overall, 259 patients were included in the study. PE was idiopathic in 135 patients, while it was associated with at least a temporary risk factor for VTE in 124 patients. After an average follow-up period of 46 months, 37 patients were found to have persistent dyspnea that was unexplained in 5 patients. Among these patients, a diagnosis of CTPH was confirmed in two patients with idiopathic PE (0.8% of the overall study population [95% confidence interval (CI), 0.0 to 1.9]; 1.5% of patients with idiopathic PE [95% CI, 0.0 to 3.6]). The diagnosis was made 14 and 22 months, respectively, after the acute PE.

Conclusions: The incidence of CTPH observed in this study was about 1%. CTPH was observed in two patients with idiopathic PE.