[Anticoagulation after an acute pulmonary embolism]

In order to determine the optimal duration of anticoagulation after an acute pulmonary embolism, the benefit risk balance needs to be analysed based on the risk of recurrent venous thromboembolism in the absence of anticoagulation and the risk of bleeding while on anticoagulant therapy. Such evaluation take in account the frequency and the severity of the risks; clinical variables appear more informative to predict recurrent venous thromboembolism than biochemical or morphological variables. Three major results are now available: (1) the minimal duration of anticoagulation for pulmonary embolism is 3 months; (2) after pulmonary embolism that was provoked by a major transient risk factor, the risk of recurrence is low and does not justify to prolong anticoagulation beyond 6 months; and (3), in patients with an unprovoked pulmonary embolism (high risk of recurrence), the prolongation of anticoagulation up to 1 or 2 years as compared to 3 or 6 months is not associated with a long term reduction in the risk of recurrence and, consequently, these patients should be treated either during 3 to 6 months or indefinitely. This last observation has two major implications: first, to identify, among patients with unprovoked pulmonary embolism, those who have a low risk of recurrence and who do not require indefinite anticoagulation; and second, in those who are eligible for indefinite anticoagulation, to reduce the risk of bleeding. If direct oral anticoagulant therapies are promising, however, additional clinical trials are needed to help physician for the daily practice.