Management of INR 5.96 in a Patient with Prosthetic Heart Valve on Warfarin
For a patient with a prosthetic heart valve and INR of 5.96 without active bleeding, immediately hold warfarin and administer oral vitamin K 2.5-5 mg, with INR rechecked within 24 hours. 1, 2, 3
Immediate Assessment
- Evaluate for any signs of bleeding including gross hemorrhage, occult bleeding (melena, hematuria), intracranial hemorrhage symptoms (headache, altered mental status), or bleeding at any site. 2
- Assess bleeding risk factors including advanced age (≥65 years), renal insufficiency, history of gastrointestinal bleeding or stroke, concomitant antiplatelet agents or NSAIDs, and alcohol use. 4, 2
- Determine valve type and position as this influences thrombosis risk during anticoagulation interruption—mitral mechanical valves carry higher thrombotic risk than aortic valves. 4
Management Algorithm for INR 5.96 WITHOUT Active Bleeding
The risk of major bleeding rises considerably when INR exceeds 4.5 and exponentially above 6.0, requiring reversal of anticoagulation. 4, 1
Primary Intervention:
- Stop warfarin immediately. 4, 1, 2
- Administer oral vitamin K1 2.5-5 mg (some guidelines support up to 5-10 mg for INR approaching 6.0). 1, 2, 3
- Expect INR reduction within 24-48 hours—oral vitamin K reduces INR in 95% of patients within 24 hours. 2, 3
- Recheck INR within 24 hours to ensure appropriate response. 1, 2, 3
Critical Consideration for Prosthetic Valves:
- In patients with prosthetic heart valves, intravenous vitamin K should NOT be used because rapid INR reduction creates risk of valve thrombosis. 4, 1
- Allow INR to fall gradually with oral vitamin K rather than aggressive IV reversal. 4
- The patient should be admitted to hospital for monitoring given the prosthetic valve and elevated thrombotic risk during subtherapeutic anticoagulation. 4
Management Algorithm for INR 5.96 WITH Active Bleeding
If bleeding is present:
- Administer vitamin K 5-10 mg by slow IV infusion immediately. 4, 1, 2
- Give prothrombin complex concentrate (PCC) as it normalizes INR within 15 minutes and is preferred over fresh frozen plasma. 1
- Fresh frozen plasma (FFP) is an alternative if PCC unavailable—it immediately drops INR to approximately 2.4. 1
- Vitamin K must be given in combination with PCC/FFP to maintain effect since Factor VII half-life is only 6 hours. 1
Resuming Anticoagulation
- Once INR normalizes and bleeding risk is controlled, warfarin can be resumed at a lower dose than previously required. 4
- Consider bridging with heparin if the patient is at high thrombotic risk (mitral mechanical valve, history of thromboembolism, atrial fibrillation, older-generation valve). 4
- Target INR for mechanical aortic valve is 2.5 (range 2.0-3.0) for current-generation bileaflet valves without additional risk factors. 4
- Target INR for mechanical mitral valve is 3.0 (range 2.5-3.5) for all mechanical valves. 4, 5
Investigate Underlying Cause
Identify precipitating factors for the elevated INR: 1, 2
- Drug interactions (antibiotics, amiodarone, NSAIDs, azole antifungals)
- Dietary changes (increased vitamin K intake or decreased intake)
- Acute illness or infection
- Liver dysfunction or heart failure decompensation
- Medication non-adherence or dosing errors
Common Pitfalls to Avoid
- Avoid high-dose vitamin K (>10 mg) routinely as it can create warfarin resistance and induce a hypercoagulable state. 4, 2
- Never use IV vitamin K in stable prosthetic valve patients due to valve thrombosis risk from rapid overcorrection. 4, 1, 2
- Do not restart warfarin at the same dose—the INR elevation indicates the previous dose was excessive. 2
- Avoid LMWH in prosthetic valve patients unless anti-Xa levels are monitored, as FDA and guidelines warn against its use for thromboprophylaxis in this population. 4