What is the initial treatment for a patient diagnosed with a pulmonary embolus?

Initial Treatment of Pulmonary Embolism

The initial treatment for a patient diagnosed with pulmonary embolism should be anticoagulation with either intravenous heparin or direct oral anticoagulants (DOACs), with treatment selection based on hemodynamic stability and risk stratification. 1

Risk Stratification

Before initiating treatment, risk stratification is essential to determine the appropriate management approach:

• Use validated scales such as PESI (Pulmonary Embolism Severity Index), sPESI (simplified PESI), or Hestia criteria 1
• Evaluate for hemodynamic instability (hypotension, shock)
• Assess for right ventricular dysfunction using echocardiography or CT

Treatment Algorithm

1. Hemodynamically Unstable PE (Massive PE)

For patients with PE and hemodynamic compromise:

• Thrombolytic therapy is recommended as it reduces mortality 1
• Alteplase (rtPA) 100 mg over 2 hours or 0.6 mg/kg over 15 minutes (maximum 50 mg) 1
• For massive PE, a 50 mg bolus of rtPA is recommended 1
• Before thrombolysis, stop heparin; after treatment, resume with maintenance dose 2

Absolute contraindications to thrombolysis:

• Hemorrhagic stroke (any time)
• Ischemic stroke within 6 months
• Central nervous system damage or neoplasms
• Recent major trauma/surgery/head injury
• GI bleeding within the last month
• Known active bleeding 1

2. Hemodynamically Stable PE

A. Parenteral Anticoagulation Options:

• Low Molecular Weight Heparin (LMWH): 1 mg/kg every 12 hours SC or 1.5 mg/kg once daily SC 1
• Unfractionated Heparin (UFH):
  • Initial bolus: 80 units/kg or 5,000-10,000 IU
  • Maintenance: 18 units/kg/hour or 1,300 IU/hour
  • Adjust to maintain APTT 1.5-2.5 times control (45-75 seconds) 2, 1
• Fondaparinux: Another recommended option 1

B. Direct Oral Anticoagulants (DOACs):

• Preferred over vitamin K antagonists in most patients due to better efficacy and safety profile 1
• Apixaban:
  • Can be initiated directly without prior parenteral anticoagulation
  • 10 mg twice daily for 7 days, followed by 5 mg twice daily
  • Consider reduced dose (2.5 mg twice daily) for extended treatment (>6 months) 1, 3
• Rivaroxaban: Another recommended DOAC option 1

C. Vitamin K Antagonists (Warfarin):

• Initial dose: 5-10 mg daily for 2 days
• Subsequent dose: 1-10 mg daily, adjusted to maintain INR 2-3
• Continue parenteral anticoagulation for at least 5 days and until INR ≥2.0 for 24 hours 2

Special Populations

Pregnancy

• LMWH is the treatment of choice
• Warfarin and DOACs should be avoided due to teratogenicity 1

Cancer

• LMWH is preferred over VKAs or DOACs for at least 6 months
• Continue treatment while cancer is active 1

Severe Renal Insufficiency

• Avoid DOACs
• Consider UFH with careful monitoring 1

Triple Positive Antiphospholipid Syndrome

• DOACs not recommended
• Use vitamin K antagonists 3

Monitoring and Follow-up

• After initial UFH bolus: Check APTT in 4-6 hours
• After any dose change: Check APTT in 6-10 hours
• Once therapeutic: Check APTT daily 2
• Discontinue heparin 5 days after starting warfarin if INR ≥2.0 2
• Re-evaluate patients at 3-6 months after the acute episode 1

Duration of Anticoagulation

• Secondary PE due to transient/reversible risk factors: 3 months
• Unprovoked or persistent risk factors: Extended (>3 months)
• Recurrent PE: Indefinite 1

Common Pitfalls and Caveats

• Don't delay anticoagulation while awaiting confirmatory testing if clinical suspicion is high
• Don't use DOACs in hemodynamically unstable patients requiring thrombolysis 3
• Don't miss PE in patients with isolated dyspnea, elderly patients, or those with severe cardiorespiratory disease 2
• Don't remove indwelling epidural/intrathecal catheters earlier than 24 hours after the last dose of apixaban 3
• Don't administer next dose of apixaban earlier than 5 hours after catheter removal 3