What is the best course of treatment for a 70-year-old patient with a diagnosis of pulmonary embolism (PE), presenting with tachycardia, stable blood pressure, and hypoxemia on room air, with a computed tomography (CT) scan showing emboli in the right lower and upper lobes?

Management of Segmental and Subsegmental PE in a 70-Year-Old with Stable Hemodynamics

This patient should be admitted for initiation of therapeutic anticoagulation with either a direct oral anticoagulant (DOAC) or low-molecular-weight heparin (LMWH), as they have confirmed pulmonary embolism with intermediate-risk features including tachycardia and borderline hypoxemia. 1, 2

Risk Stratification

This patient falls into the intermediate-risk category based on the following assessment:

• Hemodynamically stable: Current blood pressure 138/69 mmHg (not meeting high-risk criteria of SBP <90 mmHg) 2
• Tachycardia present: Heart rate 96-110 bpm suggests physiologic stress 2
• Borderline hypoxemia: Oxygen saturation 94% on room air indicates impaired gas exchange 2
• Normal RV/LV ratio: CT shows no right ventricular dysfunction, which is reassuring 1, 2
• Normal IVC contrast reflux: No evidence of right heart strain 1

The European Society of Cardiology explicitly states that thrombolytic therapy should NOT be routinely administered in intermediate- or low-risk PE patients. 1 This patient does not meet criteria for high-risk PE (massive PE with shock or persistent hypotension), so thrombolysis is not indicated. 1, 2

Admission Decision

This patient requires hospital admission based on multiple exclusion criteria for outpatient management:

• Heart rate >110 bpm (intermittently) 2
• Oxygen saturation <95% on room air 2
• Age 70 years (elderly patients warrant closer monitoring) 2
• Respiratory rate reached 32/min (indicating respiratory distress) 1

The European Society of Cardiology states that heart rate >110 bpm or oxygen saturation <90% are specific contraindications to outpatient management. 2 While this patient's oxygen saturation is 94% (not <90%), the combination of borderline hypoxemia, tachycardia, and variable respiratory rate (19-32) warrants inpatient monitoring. 2

Initial Anticoagulation Strategy

Preferred approach: Direct Oral Anticoagulant (DOAC)

The European Society of Cardiology recommends NOACs (rivaroxaban, apixaban, edoxaban, or dabigatran) as preferred over traditional LMWH-VKA regimens for hemodynamically stable PE patients. 1, 3

Specific DOAC options:

• Rivaroxaban: 15 mg twice daily with food for 21 days, then 20 mg once daily 4
• Apixaban: 10 mg twice daily for 7 days, then 5 mg twice daily 1, 3

These agents have demonstrated non-inferiority to enoxaparin/warfarin with similar or reduced bleeding risk. 5, 6

Alternative approach: LMWH bridging to warfarin

If DOACs are contraindicated (e.g., severe renal impairment with CrCl <15 mL/min, drug interactions), use LMWH overlapped with warfarin until INR reaches 2.0-3.0 (target 2.5). 1, 3

Supplemental Oxygen Management

Administer supplemental oxygen to maintain SaO₂ ≥90%. 2 This patient's current saturation of 94% on room air is borderline, and oxygen should be readily available if saturation drops below 90%. 2

Monitoring During Hospitalization

Monitor for:

• Hemodynamic deterioration: Worsening hypotension, increasing heart rate, or development of shock would necessitate escalation to thrombolysis 1
• Respiratory status: Increasing oxygen requirements or respiratory rate 1
• Bleeding complications: Particularly given the initial blood pressure reading of 150/123 mmHg (though this has normalized) 1
• Right ventricular function: Serial echocardiography if clinical deterioration occurs 1, 7

Duration of Anticoagulation

Minimum 3 months of therapeutic anticoagulation is required for all PE patients. 1, 3

The decision to continue beyond 3 months depends on:

• Provoked vs. unprovoked PE: If this PE is related to a major transient/reversible risk factor (surgery, trauma, prolonged immobilization), discontinue after 3 months 1, 3
• Unprovoked PE or persistent risk factors: Consider indefinite anticoagulation 1, 3
• Bleeding risk assessment: Reassess at regular intervals during extended therapy 1

Special Considerations for Subsegmental PE

The CT report mentions "probable embolus within a subsegmental branch" of the right upper lobe. The British Thoracic Society notes that subsegmental PE confined to this level may have uncertain clinical significance, and some evidence suggests untreated minor PE has low recurrence rates. 1 However, given this patient's symptoms (tachycardia, hypoxemia, tachypnea) and the presence of segmental PE in the right lower lobe, full anticoagulation is clearly indicated. 1

Follow-Up Care

The European Society of Cardiology recommends routine re-evaluation at 3-6 months post-PE to assess for:

• Persistent dyspnea or functional limitation 1, 3
• Signs of chronic thromboembolic pulmonary hypertension (CTEPH) 1, 3
• Need for continued anticoagulation 1, 3

If symptoms persist beyond 3 months with mismatched perfusion defects on V/Q scan, refer to a pulmonary hypertension/CTEPH expert center. 1

Common Pitfalls to Avoid

• Do not use thrombolysis in this intermediate-risk patient unless hemodynamic deterioration occurs 1, 2
• Do not routinely place IVC filters - these are reserved for patients with absolute contraindications to anticoagulation or recurrent PE despite adequate anticoagulation 1
• Do not delay anticoagulation - treatment should begin immediately upon diagnosis confirmation 1, 3
• Do not discharge this patient for outpatient management given the exclusion criteria present 2