Derivation of a clinical prediction score for chronic thromboembolic pulmonary hypertension after acute pulmonary embolism

Introduction: Validated risk factors for the diagnosis of chronic thromboembolic pulmonary hypertension (CTEPH) after acute pulmonary embolism (PE) are currently lacking. Methods: This is a post hoc patient-level analysis of three large prospective cohorts with a total of 772 consecutive patients with acute PE, without major cardiopulmonary or malignant comorbidities. All underwent echocardiography after a median of 1.5 years. In cases with signs of pulmonary hypertension, additional diagnostic tests to confirm CTEPH were performed. Baseline demographics and clinical characteristics of the acute PE event were included in a multivariable regression analysis. Independent predictors were combined in a clinical prediction score. Results: CTEPH was confirmed in 22 patients (2.8%) by right heart catheterization. Unprovoked PE, known hypothyroidism, symptom onset > 2 weeks before PE diagnosis, right ventricular dysfunction on computed tomography or echocardiography, known diabetes mellitus and thrombolytic therapy or embolectomy were independently associated with a CTEPH diagnosis during follow-up. The area under the receiver operating charateristic curve (AUC) of the prediction score including those six variables was 0.89 (95% confidence interval [ CI] 0.84-0.94). Sensitivity analysis and bootstrap internal validation confirmed this AUC. Seventy-three per cent of patients were in the low-risk category (CTEPH incidence of 0.38%, 95% CI 0-1.5%) and 27% were in the high-risk category (CTEPH incidence of 10%, 95% CI 6.5-15%). Conclusion: The 'CTEPH prediction score' allows for the identification of PE patients with a high risk of CTEPH diagnosis after PE. If externally validated, the score may guide targeting of CTEPH screening to at-risk patients.