Pulmonary Embolism — CTA Filling Defect

A 58-year-old woman, 10 days post-total knee replacement, presents with sudden-onset dyspnea, pleuritic chest pain, hemoptysis, and syncope. Vitals: BP 92/60 mmHg, HR 128/min, RR 28/min, SpO₂ 86% on room air. Wells score is 7 (high probability). CT pulmonary angiogram (CTPA) is performed and shows the finding marked **A** in the diagram — a large intraluminal filling defect in the right main pulmonary artery extending into lobar branches. Bedside echocardiography demonstrates McConnell's sign, and troponin and BNP are elevated. Which of the following is the most appropriate immediate management for this patient?