The patient’s presentation with sudden-onset shortness of breath, tachycardia, pleuritic chest pain, and recent leg swelling suggests a high probability of pulmonary embolism (PE). Immediate anticoagulation with heparin is critical to prevent clot propagation and reduce mortality. Simultaneously, CT pulmonary angiography (CTPA) is the diagnostic test of choice to confirm PE due to its high sensitivity and specificity. Delaying anticoagulation until imaging risks worsening thromboembolism. This management aligns with current guidelines emphasizing prompt treatment in suspected PE with hemodynamic stability.

Reference: Harrison’s Principles of Internal Medicine, J. Larry Jameson et al., 20th Edition.