Inclusion Criteria:  definite PE with expected life expectancy of more than 3 months - Age ≥ 18 years old. Patients with a first episode of symptomatic pulmonary embolism, diagnosed by CT angiography or pulmonary scintigraphy and treated in a conventional manner. Having received oral information about the study and having expressed a non-opposition to participate to the study Benefiting from a social security scheme  Exclusion Criteria:  Patients with pulmonary hypertension. Patients who have already had a recurrence of pulmonary embolism or deep vein thrombosis of the lower limbs. Patients with a contraindication to performing a lung ventilation-perfusion scintigraphy. Patients at high risk of recurrence of venous thromboembolic disease (severe thrombophilia or active cancer). Classical contraindications to anticoagulants. Vulnerable patients: pregnant women, under guardianship or curatorship Premature termination of participation Recurrent pulmonary embolism diagnosed by CT angiography, or deep vein thrombosis diagnosed by venous Doppler ultrasound of the lower limbs within the first 3 or 6 months depending on the nature of the VTE. Occurence of pulmonary hypertension detected by trans-thoracic ultrasound (systolic pulmonary arterial pressure more than 35 mmgh).