What is the recommended duration of heparin (Heparin) therapy for patients with pulmonary embolism (PE)?

Duration of Heparin Therapy for Pulmonary Embolism

Heparin therapy for pulmonary embolism should be continued for at least 5 days and until the INR is between 2.0 and 3.0 for at least 2 consecutive days when transitioning to oral anticoagulants. 1

Initial Heparin Therapy

Unfractionated Heparin (UFH)

• Initial bolus: 5,000-10,000 IU
• Maintenance dose: 1,300 IU/hour or 18 IU/kg/hour
• Adjust to maintain APTT ratio of 1.5-2.5 times control (45-75 seconds) 1
• APTT monitoring schedule:
  • After initial bolus: 4-6 hours later
  • After any dose change: 6-10 hours later
  • Once therapeutic: Daily 1

Low Molecular Weight Heparin (LMWH)

• Weight-adjusted dosing (e.g., enoxaparin 1 mg/kg twice daily or dalteparin 200 U/kg once daily)
• Preferred over UFH for hemodynamically stable patients 1
• No routine monitoring required except in severe renal failure or pregnancy 1

Duration of Heparin Therapy

The European Society of Cardiology guidelines clearly state that:

• Parenteral anticoagulation (UFH, LMWH, or fondaparinux) should be continued for at least 5 days 1
• Heparin should be discontinued when the INR is between 2.0-3.0 for at least 2 consecutive days on vitamin K antagonist therapy 1
• Oral anticoagulants (warfarin) should be initiated as soon as possible, preferably on the same day as initial anticoagulant 1

Transition to Oral Anticoagulation

• Start warfarin at 5-7.5 mg (preferred over higher doses, especially in older patients) 1
• Continue heparin and warfarin together for at least 5 days
• Stop heparin only when INR is between 2.0-3.0 for at least 2 consecutive days 1

Special Considerations

High-Risk PE (with shock or hypotension)

• Intravenous UFH is preferred over LMWH or fondaparinux 1
• Consider thrombolytic therapy if appropriate 1

Cancer Patients

• LMWH is recommended for at least 6 months rather than transitioning to vitamin K antagonists 1
• Continue anticoagulation as long as cancer remains active 1

Duration of Overall Anticoagulation Therapy

• First PE with major transient/reversible risk factor: 3 months 2
• Unprovoked PE or persistent risk factors: Extended treatment (>3 months) 2
• Recurrent PE: Indefinite anticoagulation 2

Common Pitfalls to Avoid

1. Premature discontinuation of heparin: Never stop heparin before 5 days of therapy, even if INR reaches therapeutic range earlier 1

2. Inadequate APTT monitoring: For UFH, failure to achieve adequate anticoagulation (APTT >1.5 times control) is associated with a high risk (25%) of recurrent venous thromboembolism 3

3. Excessive initial warfarin dosing: Starting with 10 mg doses can lead to excessive anticoagulation, especially in older patients 1

4. Overlooking renal function: In patients with severe renal failure (creatinine clearance <25-30 ml/min), UFH with careful monitoring is preferred over LMWH 1

5. Missing the transition window: Ensure overlap between heparin and oral anticoagulant for at least 5 days to prevent thrombotic complications 1