The agent of choice in the initial management of pulmonary embolism is?

Heparin is the agent of choice in the initial management of pulmonary embolism due to its rapid onset of action and ability to be closely monitored through activated partial thromboplastin time (aPTT) measurements. When treating a pulmonary embolism, immediate anticoagulation is essential to prevent further clot extension and promote the body’s natural fibrinolytic mechanisms to dissolve the existing clot.

Heparin can be administered intravenously, allowing for dose adjustments based on the patient's response. This is particularly important in acute settings where rapid control of anticoagulation is needed. It can also be used in the context of patients with renal impairment, where other anticoagulants may not be advisable.

While other options like warfarin, fondaparinux, and direct oral anticoagulants (DOACs) play significant roles in long-term management and alternative treatment pathways, they do not offer the same rapid therapeutic effect needed to address acute pulmonary embolism effectively. Warfarin requires several days for therapeutic anticoagulation to be achieved and must be bridged with heparin initially. Fondaparinux also has anticoagulant properties but is typically utilized after the initial heparin phase. Direct oral anticoagulants are generally considered for outpatient