Incidence and Predictors of Chronic Thromboembolic Pulmonary Hypertension (CTEPH) following acute pulmonary embolism

Background: Late obstructive pulmonary artery remodeling presented as CTEPH portends adverse sequelae and therapeutic challenges. Although progressive dyspnea on exertion beyond three-month period of treatment with anticoagulants is a diagnostic cornerstone, uncertainty still surrounds early identification and treatment of the patients.Methods: We have conducted a prospective study for 310 patients survived after first episode of acute pulmonary embolism (PE) who were treated by anticoagulants for at least 3 months. Patients with preexisting pulmonary hypertension (PH), severe chronic obstructive pulmonary disease (COPD), and low ejection fraction (EF) in baseline echocardiography (EF<30%) were excluded. Complete follow-up for 290 subjects were performed. Demographic, clinical, electrocardiogram (ECG) features, and imaging findings of participants were recorded. According to a predetermined stepwise diagnostic protocol, patients with exertional Dyspnea and PH probable features in echocardiography underwent lung perfusion scan.Results: Cumulative incidence of CTEPH was 8.6% (n=25). There was no patient with normal baseline right ventricular (RV) function in CTEPH group. In the same way none of these patients had only segmental involvement in baseline CT angiography (CTA) in CTEPH group. Greater proportion of CTEPH group received fibrinolytic therapy, however the difference was nonsignificant (2.6% versus 8 %, P: 0.16). Multivariate logistic regression demonstrated significant association of baseline RV diameter in echocardiography as well as RV strain in CTA with development of CTEPH. Corresponding odds ratios were 1.104(1.038 -1.175, P: 0.002) per 1mm increase in RV diameter and 2.387 (0.941- 6.054, P: 0.051), respectively.Conclusion: We found that incidence of CTEPH was relatively high in the present investigation. RV diameter and RV dysfunction were independent predictors of CTEPH.