Diagnostic Strategy for Suspected Pulmonary Embolism Based on 4PEPS

The increased use of diagnostic imaging and especially computed tomography pulmonary angiography in patients suspected of pulmonary embolism (PE) is an important point of concerns. The goal of this pragmatic cluster-randomized trial is to compare the diagnostic strategy based on the four-level pulmonary embolism probability score (4PEPS) and current practices. The main questions it aims to answer is: "Does the diagnostic strategy based on 4PEPS significantly reduce the use of thoracic imaging without increasing the risk of serious adverse events as compared to current diagnostic practices?" Patients suspected of having PE in the participating emergency departments will be included and followed for 90 days. In ten centers, the emergency physicians will apply the 4PEPS strategy and in ten other centers, the emergency physicians will be free to do as they see fit. Researchers will compare the two groups of patients to see if the rate of diagnostic thoracic imaging tests and the rate of adverse events related to diagnostic strategies will differ.

Inclusion Criteria: * Admission to an emergency department participating in the study. * Suspected PE due to thoracic symptoms (dyspnea, chest pain, or hemoptysis) and/or syncope without any other obvious explanation after clinical examination and possible additional first-line tests (ECG, chest X-ray, or routine lab work-up). Exclusion Criteria: * Age \< 18 years. * Known result of a specific diagnostic imaging examination for PE (thoracic CT angiography, pulmonary scintigraphy, or venous ultrasound of the lower limbs). * Hemodynamic instability (systolic blood pressure \< 90 mmHg or more than 40 mmHg lower than usual for more than 15 min). * Curative dose of anticoagulant in place for more than two days prior to inclusion. * Pregnant or parturient patient. * Patient in detention by judicial or administrative decision. * Patient undergoing compulsory psychiatric treatment. * Patient placed under a legal protection measure. * Patient who objects to participating in the research (preliminary phase) or is unable to give free and informed consent (active phase).