Anticoagulant treatment for acute pulmonary embolism: a pathophysiology-based clinical approach

The management of patients with acute pulmonary embolism is made challenging by its wide spectrum of clinical presentation and outcome, which is mainly related to patient haemodynamic status and right ventricular overload. Mechanical embolic obstruction and neurohumorally mediated pulmonary vasoconstriction are responsible for right ventricular overload. The pathophysiology of acute pulmonary embolism is the basis for risk stratification of patients as being at high, intermediate and low risk of adverse outcomes. This risk stratification has been advocated to tailor clinical management according to the severity of pulmonary embolism. Anticoagulation is the mainstay of the treatment of acute pulmonary embolism. New direct oral anticoagulants, which are easier to use than conventional anticoagulants, have been compared with conventional anticoagulation in five randomised clinical trials including >11 000 patients with pulmonary embolism. Patients at high risk of pulmonary embolism (those with haemodynamic compromise) were excluded from these studies. Direct oral anticoagulants have been shown to be as effective and at least as safe as conventional anticoagulation in patients with pulmonary embolism without haemodynamic compromise, who are the majority of patients with this disease. Whether these agents are appropriate for the acute-phase treatment of patients at intermediate–high risk pulmonary embolism (those with both right ventricle dysfunction and injury) regardless of any risk stratification remains undefined.