Pharmacotherapy Case 13: Chronic Anticoagulation Management By: Dr. Nehad Ahmed

 

Chief Complaint:

A 72-year-old female presents for routine follow-up to assess the management of her chronic anticoagulation therapy. The patient has a history of atrial fibrillation and deep vein thrombosis (DVT). She is concerned about managing her anticoagulation therapy, specifically her recent difficulty in maintaining therapeutic INR levels.

Subjective Data:

History of Present Illness (HPI):
The patient reports feeling generally well, but she is concerned about maintaining an appropriate therapeutic range for her international normalized ratio (INR). She mentions that over the past 6 months, her INR levels have fluctuated despite consistent adherence to her prescribed warfarin regimen. Her most recent INR was 2.9, which is at the higher end of the therapeutic range. She denies any significant bleeding or clotting events. The patient also reports occasional dizziness when standing up quickly but denies any chest pain, shortness of breath, or swelling in her legs. She is worried about the risk of bleeding or developing a clot due to her fluctuating INR.

Past Medical History (PMH):

Atrial fibrillation (AF), diagnosed 4 years ago

Deep vein thrombosis (DVT) in the left lower extremity, diagnosed 3 years ago

Hypertension, diagnosed 10 years ago

Type 2 diabetes mellitus, diagnosed 5 years ago

Hyperlipidemia, diagnosed 8 years ago

Osteoarthritis, managed with acetaminophen

No prior history of major bleeding or stroke.

Medications:

Warfarin 5 mg daily (currently adjusted based on INR)

Lisinopril 20 mg daily for hypertension

Metformin 500 mg twice daily for diabetes

Simvastatin 20 mg nightly for hyperlipidemia

Acetaminophen 325 mg every 6 hours as needed for osteoarthritis

No other medications or herbal supplements reported.

Allergies:

No known drug allergies (NKDA).

Family History:

Father had a history of stroke at age 75 and hypertension.

Mother had type 2 diabetes and cancer.

Social History:

Smoking: Never smoked.

Alcohol: Drinks wine socially, about 2-3 glasses per week.

Physical activity: Limited physical activity due to osteoarthritis. Walks around the house but avoids strenuous activity.

Diet: Generally balanced, but occasionally eats a high-fat, high-sodium diet.

 

Review of Systems:

Cardiovascular: No palpitations, chest pain, or swelling in the extremities.

Respiratory: No shortness of breath or cough.

Gastrointestinal: No nausea, vomiting, or abdominal pain.

Neurological: Occasional dizziness, no confusion, or loss of coordination.

Musculoskeletal: Pain in knees due to osteoarthritis but manageable with acetaminophen.

Objective Data:

Vital Signs upon Arrival:

Blood Pressure: 132/78 mmHg

Heart Rate: 78 bpm (regular rhythm)

Respiratory Rate: 16 breaths/min

Temperature: 36.7°C (98°F)

Oxygen Saturation: 97% on room air

Weight: 82 kg (BMI 28.4 kg/m²)

Height: 162 cm

Physical Exam:

General: Alert, oriented, and in no acute distress.

Cardiovascular:

Regular rate and rhythm, no murmurs or gallops.

Peripheral pulses intact, no edema in the lower extremities.

Respiratory: Clear lung fields bilaterally, no wheezes or crackles.

Abdomen: Soft, non-tender, no hepatomegaly or ascites.

Musculoskeletal: Mild tenderness in both knees due to osteoarthritis.

Neurological: No focal deficits, cranial nerves intact, normal strength and sensation.

Laboratory Results:

INR (most recent): 2.9 (therapeutic range for atrial fibrillation: 2.0-3.0)

Complete Blood Count (CBC): Normal white blood cell count, hemoglobin 13.8 g/dL, hematocrit 41.5%.

Electrolytes: Sodium 140 mEq/L, Potassium 4.2 mEq/L, Chloride 103 mEq/L

Creatinine: 0.8 mg/dL (normal renal function)

Liver Function Tests (LFTs): Normal

Blood Glucose: 112 mg/dL (within target range for diabetes)

Lipid Profile:

Total Cholesterol: 190 mg/dL

LDL: 110 mg/dL

HDL: 60 mg/dL

Triglycerides: 140 mg/dL

 

Electrocardiogram (ECG):

Sinus rhythm, no signs of atrial fibrillation, or other arrhythmias.

No ST-segment changes or evidence of ischemia.

Ultrasound of Lower Extremities:

No signs of deep vein thrombosis (DVT) in the legs.

Assessment:

The patient is a 72-year-old female with a history of atrial fibrillation (AF) and DVT, currently on chronic anticoagulation therapy with warfarin. Her most recent INR is 2.9, which is within the therapeutic range for stroke prevention in atrial fibrillation (INR target: 2.0-3.0). The patient reports no signs or symptoms of bleeding, clotting, or any other complications related to anticoagulation therapy. She expresses concern about her fluctuating INR levels, but there are no significant signs of over-anticoagulation or bleeding risk at this time. The patient is stable on her current regimen, and there is no evidence of DVT or other acute complications.

Plan:

Anticoagulation Management:

Continue warfarin therapy at the current dose of 5 mg daily, as the patient’s INR is within the target range of 2.0-3.0.

Monitor INR regularly (every 1-2 weeks) to ensure that it remains stable.

Advise the patient on consistency in her diet (especially regarding vitamin K intake), as fluctuations in vitamin K-rich foods (e.g., leafy greens) can cause changes in INR.

Encourage the patient to avoid over-the-counter medications (especially NSAIDs) and ensure she reports any changes in medication or new prescriptions.

Consider transitioning to a direct oral anticoagulant (DOAC) (e.g., apixaban or rivaroxaban) if the patient continues to experience difficulty managing warfarin, provided there are no contraindications (e.g., renal insufficiency).

Lifestyle Modifications:

Dietary education: Reinforce the importance of maintaining a consistent intake of vitamin K-rich foods to prevent fluctuations in INR. Recommend consulting with a nutritionist for personalized dietary advice.

Smoking cessation: Although the patient does not smoke, continue to encourage maintaining a healthy lifestyle, including a balanced diet, exercise, and avoiding excessive alcohol intake.

Physical activity: Recommend gentle exercises to help manage weight and improve cardiovascular health, considering the patient’s osteoarthritis.

Pressure and Diabetes Management:

Continue lisinopril for blood pressure management and metformin for diabetes management. Monitor blood pressure and glucose levels regularly.

Regular monitoring of renal function and liver enzymes given the long-term use of warfarin.

Pain Management:

Continue using acetaminophen for osteoarthritis pain. Avoid NSAIDs due to potential bleeding risk with warfarin therapy.

Follow-up:

Follow-up in 1-2 weeks for a repeat INR check and review of any changes in health status.

Continue regular visits every 3-6 months to monitor for potential complications of anticoagulation therapy (e.g., bleeding or thrombosis).

Follow-up with a cardiologist if there are concerns about atrial fibrillation control or the need for alternative anticoagulation therapy.

Patient Education:

Educate the patient about the signs of major bleeding (e.g., bruising, blood in stool, urine, or vomit) and thrombosis (e.g., swelling, pain, or redness in the extremities).

Reinforce the importance of consistent INR monitoring, the potential risks of warfarin, and how to manage them.

Encourage regular exercise and weight management as part of overall health maintenance.

Discussion:

Chronic anticoagulation therapy is essential in patients with atrial fibrillation and a history of venous thromboembolism to prevent stroke and recurrent thrombotic events. Managing warfarin therapy can be challenging due to fluctuations in INR levels, but with regular monitoring, education, and adjustments, therapeutic levels can be maintained. Switching to a direct oral anticoagulant (DOAC) could provide more stable anticoagulation without the need for frequent monitoring.

In this case, the patient’s INR is within the target range, and she does not report any complications, indicating good anticoagulation management. Continued monitoring and patient education are key to preventing complications such as bleeding or thrombosis.