A 68-year-old woman comes to the office for follow-up of her anticoagulation therapy. Her medical problems include chronic atrial fibrillation, hypertension, congestive heart failure (CHF) NYHA II, and coronary artery disease. Her medications include daily warfarin 6 mg, lisinopril, furosemide, and carvedilol. She started taking an over-the-counter supplement 2 weeks ago to help increase her energy level but cannot recall the name. She denies bleeding episodes. Echocardiogram performed 2 months ago shows a dilated left atrium and moderately depressed left ventricular ejection fraction. Laboratory evaluation done early in the morning shows an international normalized ratio (INR) of 4.3 with a prothrombin time of 46 sec. Which of the following is the most appropriate next step in management?

Question

A 68-year-old woman comes to the office for follow-up of her anticoagulation therapy.  Her medical problems include chronic atrial fibrillation, hypertension, congestive heart failure (CHF) NYHA II, and coronary artery disease.  Her medications include daily warfarin 6 mg, lisinopril, furosemide, and carvedilol.  She started taking an over-the-counter supplement 2 weeks ago to help increase her energy level but cannot recall the name.  She denies bleeding episodes.  Echocardiogram performed 2 months ago shows a dilated left atrium and moderately depressed left ventricular ejection fraction.  Laboratory evaluation done early in the morning shows an international normalized ratio (INR) of 4.3 with a prothrombin time of 46 sec.  Which of the following is the most appropriate next step in management?

Quizplus · Accepted Answer

Explanation: 11ec2b69_bf5b_af60_8f63_f3335ee09b58_MD0005_00 The algorithm for treatment of a patient with supratherapeutic INR depends on the INR level and presence of clinically serious bleeding. Studies have shown that oral vitamin K is as effective as intravenous vitamin K in lowering the INR in 24 hours. Since intravenous vitamin K has a risk of anaphylaxis, oral vitamin K is the preferred route. Patients INR <4.5 and no clinical evidence of serious bleeding should have their warfarin held for 1 or 2 days and then restarted when the INR is in the therapeutic range. Patients with INR 4.5-10 and no serious bleeding should have their warfarin held and be given a low dose (1-2.5 mg) of oral vitamin K if there is an increased risk of future bleeding (eg, history of prior bleed) (Choice A). Patients with INR >10 and no serious bleeding should have their warfarin held and be given a higher dose (2.5-5 mg) of oral vitamin K. Patients with serious bleeding, regardless of the INR, should have their warfarin held and receive intravenous vitamin K as well as prothrombin complex concentrate (PCC) (Choices C and E). This patient's supratherapeutic INR is likely due to a drug interaction between the supplement and the warfarin. She has no evidence of bleeding, has INR <4.5, and can be managed by holding her warfarin for 1 or 2 days and monitoring her INR. Giving this patient higher doses of vitamin K or PCC would completely reverse anticoagulation and potentially increase the risk of future thrombotic events given her risk factors of CHF, atrial fibrillation, and dilated atrium. (Choice B) Subcutaneous vitamin K is not as effective as either oral or intravenous vitamin K and only slightly better than placebo in lowering the INR within 24 hours. As a result, it is not recommended to treat supratherapeutic INR. Educational objective: Patients with supratherapeutic international normalized ratio (INR) <4.5 on warfarin and no serious bleeding should have their warfarin held and restarted when the INR is therapeutic. Patients with supratherapeutic INR 4.5-10 and increased risk of bleeding, as well as those with supratherapeutic INR >10 and no serious bleeding, should receive oral vitamin K in addition to having their warfarin held. Oral vitamin K is the preferred route at any supratherapeutic INR unless there is serious bleeding. References: Pharmacology and management of the vitamin K antagonists: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition). (http://www.ncbi.nlm.nih.gov/pubmed/18574265) Treatment of excessive anticoagulation with phytonadione (vitamin K): a meta-analysis. (http://www.ncbi.nlm.nih.gov/pubmed/16505257)

A 68-Year-Old Woman Comes to the Office for Follow-Up of Her