Indications and Duration of Therapy
Recommended Therapeutic Range and Duration of Therapy with Warfarin
Adapted from the 9th Edition of the CHEST guidelines:
| Indication | INR Range | Duration / Other Considerations |
|---|---|---|
| Antiphospholipid Syndrome | 2.0-3.0 | indefinite (2B) |
| DVT and PE | ||
| Transient/reversible risk factor | 2.0-3.0 | 3 months (1B) |
| Unprovoked | 2.0-3.0 | at least 3 months (1B) then reevaluate |
| Second episode of unprovoked | 2.0-3.0 | extended (1B) |
| Non-Valvular Atrial Fibrillation/Atrial Flutter | ||
| CHADS2 = 0 (low CVA risk) | N/A | no therapy (2B) or ASA 75-325mg (2B) |
| CHADS2 = 1 (intermediate CVA risk) | N/A | dabigatran (2B) |
| CHADS2 ≥ 2 (high CVA risk) | N/A | dabigatran (2B) |
| With mitral stenosis | 2.0-3.0 | long-term (1B) |
| With stable CAD | 2.0-3.0 | long-term (2C) |
| Prior to/following cardioversion to NSR | 2.0-3.0 | 3 weeks/4weeks (1B) |
| Mechanical Heart Valve | ||
| Aortic | 2.0-3.0 | long-term (1B) |
| Mitral | 2.5-3.5 | long-term (2C) |
| Bioprosthetic heart valve | ||
| Aortic | N/A | aspirin 50-100mg (2C) |
| Mitral | 2.0-3.0 | 3 months then switch to ASA (2C) |
| Cardioembolic Ischemic Stroke | N/A | dabigatran (2B) |
Reference:
Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines 2012
Strength of Recommendations Grading System
From the 8th edition of the CHEST guidelines:
| Indication | INR Range | Duration |
| Antiphospholipid Syndrome | ||
| No additional risk factors | 2.0-3.0 | indefinite (1A) |
| Recurrent events with therapeutic INRs | 2.5-3.5 | indefinite (2C) |
| DVT and PE | ||
| Transient/reversible risk factor | 2.0-3.0 | 3 months (1A) |
| Unprovoked | 2.0-3.0 | at least 3 months (1A) then reevaluate (1C) |
| Second episode of unprovoked | 2.0-3.0 | long-term (1A) |
| After 3 months at 2.0-3.0 | 1.5-1.9 | long-term (1A) |
| With active cancer after LMWH for 3-6 months | 2.0-3.0 | indefinite (1A) or until CA resolved (1C) |
| Atrial Fibrillation/Atrial Flutter | ||
| With prior CVA/TIA or systemic embolism | 2.0-3.0 | long-term (1A) |
| CHADS2 = 0 | N/A | aspirin 75-325mg (1B) |
| CHADS2 = 1 | 2.0-3.0 | long-term (1A) or aspirin 75-325mg (1B) |
| CHADS2 ≥ 2 | 2.0-3.0 | long-term (1A) |
| With mitral stenosis | 2.0-3.0 | long-term (1B) |
| Following open heart surgery | 2.0-3.0 | 4 weeks (1B) |
| Prior to/following cardioversion to NSR | 2.0-3.0 | 3 weeks/4weeks (1C) |
| Mechanical Heart Valve | ||
| Aortic bileaflet or tilting disk | 2.0-3.0 | long-term (1B) |
| Mitral bileaflet or tilting disk | 2.5-3.5 | long-term (1B) |
| Aortic or mitral caged ball or caged disk | 2.5-3.5 | long-term (1B) |
| Any valve with additional risk factor | 2.5-3.5 | long-term (1B) |
| Any valve + suffer embolism with target INR | increase + add ASA | long-term (2C) |
| Bioprosthetic heart valve | ||
| Aortic | N/A | aspirin 50-100mg |
| Mitral | 2.0-3.0 | 3 months then switch to ASA (1B) |
| With prior h/o systemic embolism | 2.0-3.0 | 3 months then reassess (1C) |
| With LA thrombus | 2.0-3.0 | until resolution (1C) |
| Cardioembolic Ischemic Stroke | 2.0-3.0 | long-term (1A) |