The aims of follow-up of pulmonary thromboembolism (PTE) are to avoid recurrence and possible sequels, such as pulmonary hypertension and postthrombotic syndrome of the lower limbs. Recurrences are reduced by anticoagulant therapy. In most PTE triggered by a transitory risk factor, without additional risk factors, the duration of oral anticoagulant therapy (OAT) is well established. However, in at least half of all cases, the triggering factors are not clear, the risk of recurrence is higher, and the duration of OAT has not been well-defined. Consequently, the factors that increase the risk of recurrence should be identified and monitored. These factors include cancer, some thrombophilias, and recurrent PTE or deep veinous thrombosis (DVT). In the last few years, idiopathic etiology, residual venous thrombosis, and other factors such as persistent right ventricular dysfunction, have also been demonstrated to be markers of recurrence. In some patients, D-dimers also seem to predict the risk of recurrence. Finally, the duration of OAT will be defined by periodically weighing the risk of recurrence against hemorrhagic risk in each individual patient. Current evidence on the balance of risks indicates a tendency toward indefinite anticoagulation, especially in idiopathic PTE. Moreover, functional monitoring through echocardiography, at least in the first 2 years, is essential to detect pulmonary hypertension associated with chronic pulmonary thromboembolism
