Incidence of chronic thromboembolic pulmonary hypertension in patients after acute pulmonary embolism

Background: Recent studies suggest that chronic thromboembolic pulmonary hypertension (CTEPH) following acute pulmonary embolism (PE) may be more common than previously thought. Objective: To investigate the incidence of CTEPH and associated risk factors through a systematic screening in patients after acute PE in China. Methods: A cohort study of consecutive patients with acute PE in a national referral institute was retro and prospectively approached by a questionnaire for the presence of new or increased complaints of dyspnea after acute PE episode. Subsequently, these patients were evaluated for the presence of pulmonary hypertension with echocardiography, perfusion lung scanning and right heart catheterization (RHC) in follow-up period. Pulmonary hypertension was defined as a systolic pulmonary artery pressure ≥50 mmHg at rest in the presence of residual perfusion defects at perfusion lung scanning. Results: From 2006 to 2010, 488 patients with acute PE were screened, and 475 patients were included. Overall mortality after a median follow-up period of 21 months was 12.9%; 74 patients were lost to follow-up. In the remaining patients, nine were diagnosed with pulmonary hypertension by echocardiography, and two of the nine patients underwent right heart catheterization (RHC). The incidence of CTEPH after acute PE was 2.24%. In Cox regression, 173 cases which had no missing data of biomarkers were involved. The analysis showed that protein C deficiency (hazard ratio, 10.40, 95% confidence interval, 1.06 to 102.25) increased the risk of CTEPH after acute PE. Conclusions: The incidence of CTEPH after acute PE was 2.24%. Protein C deficiency may increase the risk of CTEPH.