Coumadin (Warfarin) to Heparin Conversion Before and After Elective Surgery

Number: 0200


Aetna considers continuous intravenous heparin infusion medically necessary for members taking oral anti-coagulants (warfarin) who require the maintenance of anti-coagulation prior to and after diagnostic or therapeutic procedures.  For most members, pre-procedure weaning of the oral anti-coagulant may be safely accomplished on an outpatient basis.  When circumstances arise that might compromise the member's state of anti-coagulation such that thrombotic complications may occur, up to 3 inpatient pre-procedure days may be considered medically necessary.


The most common indications for warfarin therapy are atrial fibrillation, the presence of a mechanical heart valve, prior thromboembolism, a documented left ventricular thrombus or a history of venous thromboembolism with or without a pulmonary embolism.

Patients receiving long-term warfarin therapy may present a problem if they require surgery because the interruption of anti-coagulant therapy increases their risk of thromboembolism.  Rational decisions regarding the appropriateness of peri-operative anti-coagulation depends on individual patient factors and can only be made when the risk of peri-operative thromboembolism is balanced against the risk of peri-operative bleeding.

After warfarin therapy is discontinued, it generally takes several days for its anti-thrombotic effect to recede.  Most invasive procedures can be performed safely when the international normalized ratio (INR) is less than 1.5.

Finlay et al (2010) stated that many patients undergoing catheter ablation of atrial flutter (AFL) require peri-procedural anti-coagulation.  These researchers compared a strategy of conversion to low-molecular-weight heparin (LMWH) peri-procedure to uninterrupted warfarinization in a non-randomized, case-controlled study.  A total of 101 consecutive patients requiring peri-procedural anti-coagulation for catheter ablation of typical AFL were studied.  The first 51 patients underwent conversion to LMWH (enoxaparin 1 mg/kg body weight) with a warfarin pause (LMWH group), the subsequent 50 continued with uninterrupted oral anti-coagulation (warfarin group).  Primary endpoint was a composite of major and minor bleeding complications and groin symptoms.  Fewer patients in the warfarin group reached the primary endpoint (36.0 % versus 56.8 %, p = 0.013).  Four patients in the LMWH group but no patient in the warfarin group required hospital admission for bleeding-related complications.  Cost analysis showed mean cost per patient of anti-coagulation with LMWH to be pounds sterling 100.9 (95 % confidence interval [CI]: 94.46 to 107.30) compared to pounds sterling 10.23 (95 % CI: 4.49 to 15.97) in the warfarin group (p < 0.0001).  Trans-esophageal echocardiography (TEE) was performed prior to ablation in 11 patients in the warfarin group and in 3 patients in the LMWH (p = 0.019).  When TEE costs were included, costs were pounds sterling 125.00 ($188.25) (95 % CI: 96.80 to 153.60) for the LMWH strategy and pounds sterling 108.5 ($163.40) (95 % CI: 54.92 to 162.1) for the warfarin group (p < 0.0001).  The authors concluded that catheter ablation of typical AFL without interruption of warfarin appears safer and more cost-effective than peri-procedural conversion to LMWH.  It could be used as a routine anti-coagulation strategy for the ablation of right-sided arrhythmias.

Pre-Procedure Regimen

The treating physician should determine the INR targets required for best protection against thromboembolism while minimizing the risk of bleeding for the planned procedure.  For most patients, the literature indicates that warfarin therapy may be discontinued 3 to 4 days prior to the date of the planned elective surgery to allow the INR to fall spontaneously.  On the 2nd day after discontinuing warfarin, the INR may be checked as an outpatient and when the anti-thrombotic threshold value is reached, the patient may be admitted to the hospital for continuous intravenous heparin infusion.  In most cases, this occurs on the day before or the day of the planned procedure.

Post-Procedure Regimen

When the physician decides to restart oral anti-coagulation after the procedure, an effort should be made to time the discontinuance of intravenous heparin with the establishment of adequate anti-thrombotic protection in the inpatient setting.  The literature indicates that conversion back to pre-procedure levels of oral anti-coagulation can also be bridged by using subcutaneous injections of LMWH in the home setting after discharge.

Table: CPT Codes / HCPCS Codes / ICD-10 Codes
Code Code Description

Information in the [brackets] below has been added for clarification purposes.   Codes requiring a 7th character are represented by "+":

HCPCS codes covered if selection criteria are met:

S9336 Home infusion therapy, continuous anticoagulant infusion therapy (e.g., heparin), administrative services, professional pharmacy services, care coordination, and all necessary supplies and equipment (drugs and nursing visits coded separately), per diem

Other HCPCS codes related to the CPB:

J1642 Injection, heparin sodium, (Heparin Lock Flush), per 10 units
J1643 Injection, heparin sodium (pfizer), not therapeutically equivalent to J1644, per 1000 units
J1644 Injection, heparin sodium, per 1,000 units

ICD-10 codes covered if selection criteria are met:

Z79.01 Long term (current) use of anticoagulants

The above policy is based on the following references:

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  2. Borman RJ, Danby D, Turner RC. Management of the anticoagulated patient for elective surgery. J Foot Surg. 1991;30(3):308-309.
  3. Douketis JD, Crowther MA, Cherian SS, et al. Physician preferences for perioperative anticoagulation in patients with a mechanical heart valve who are undergoing elective noncardiac surgery. Chest. 1999;116(5):1240-1246.
  4. Douketis JD, Crowther MA, Cherian SS. Perioperative anticoagulation in patients with chronic atrial fibrillation who are undergoing elective surgery: Results of a physician survey. Can J Cardiol. 2000;16(3):326-330.
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  7. Finlay M, Sawhney V, Schilling R, et al. Uninterrupted warfarin for periprocedural anticoagulation in catheter ablation of typical atrial flutter: A safe and cost-effective strategy. J Cardiovasc Electrophysiol. 2010;21(2):150-154.
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