A 58-year-old man with a 3-day history of acute dyspnea and pleuritic chest pain undergoes CT pulmonary angiography (CTPA) for suspected pulmonary embolism. The scan confirms a filling defect in the right lower lobar pulmonary artery. Additionally, the structure marked **C** in the diagram shows an RV/LV diameter ratio of 1.1 on axial imaging. His blood pressure is 128/82 mmHg, heart rate 98 bpm, and troponin I is elevated at 0.08 ng/mL (normal < 0.04). Based on these findings, which of the following is the most appropriate management strategy?

Explanation

## Why Anticoagulation alone with a DOAC is right The patient is hemodynamically stable (BP 128/82, no shock), but demonstrates RIGHT VENTRICULAR STRAIN on CTPA (RV/LV ratio 1.1, which exceeds the 0.9 threshold) combined with elevated troponin. This constellation defines INTERMEDIATE-RISK (SUBMASSIVE) PE per current risk stratification guidelines (PESI/sPESI + RV imaging + biomarkers). According to Robbins 10e Ch 4 and Harrison 21e Ch 279, intermediate-risk PE with RV dysfunction and elevated biomarkers in hemodynamically stable patients is managed with anticoagulation (DOACs preferred over warfarin for most patients) and close clinical monitoring. Systemic thrombolysis is reserved for HIGH-RISK/MASSIVE PE (hypotension or shock), which this patient does not have. Catheter-directed thrombolysis may be considered in select intermediate-high-risk cases with rapid clinical deterioration, but is not first-line for stable patients. Observation without anticoagulation would be inappropriate and dangerous given confirmed PE. ## Why each distractor is wrong - **Systemic thrombolysis (alteplase)**: Reserved for HIGH-RISK/MASSIVE PE with hemodynamic instability (hypotension, shock). This patient is hemodynamically stable; systemic thrombolysis carries significant bleeding risk and is not indicated. - **Observation without anticoagulation**: Confirmed PE with RV strain and elevated biomarkers requires anticoagulation. Observation alone risks recurrent thromboembolism and clinical deterioration. - **Immediate surgical embolectomy or catheter-directed thrombolysis**: These invasive approaches are reserved for massive PE with shock, thrombolysis contraindication, or rapid hemodynamic deterioration. They are not first-line for stable intermediate-risk patients. **High-Yield:** RV strain (RV/LV > 0.9) + elevated biomarkers in a hemodynamically stable patient = INTERMEDIATE-RISK PE → anticoagulation + monitoring, NOT thrombolysis. [cite: Robbins 10e Ch 4; Harrison 21e Ch 279]