Pharmacotherapy Case Study 10: Atrial Fibrillation By: Dr. Nehad Ahmed

 

Chief Complaint:

A 57-year-old male presents to the emergency department with complaints of palpitations, dizziness, and shortness of breath. He describes experiencing irregular, rapid heartbeats for the past few hours. He also mentions lightheadedness and feels fatigued.

Subjective Data:

History of Present Illness (HPI):
The patient reports feeling a "fluttering" or "racing" sensation in his chest, which started around 3 hours ago while he was watching TV. The palpitations are described as irregular and rapid, occurring intermittently. He also feels lightheaded and has mild shortness of breath but denies chest pain, nausea, or sweating. The palpitations have not improved with rest, and he has not tried any interventions at home.

Past Medical History (PMH):

Hypertension (diagnosed 15 years ago, poorly controlled)

Hyperlipidemia (diagnosed 5 years ago)

Type 2 Diabetes Mellitus (diagnosed 10 years ago)

Obesity (BMI 34 kg/m²)

Chronic Kidney Disease (CKD) (stage 2)

Previous history of myocardial infarction (MI), 3 years ago, with angioplasty and stent placement in the left anterior descending artery (LAD).

Atrial fibrillation (previously diagnosed but poorly controlled, non-compliant with anticoagulation therapy)

 

Medications:

Lisinopril 20 mg daily

Amlodipine 10 mg daily

Atorvastatin 40 mg nightly

Metformin 1000 mg twice daily

Aspirin 81 mg daily

Warfarin 5 mg daily (non-compliant, missed doses in the past week)

Allergies:

No known drug allergies.

Family History:

Father died of a heart attack at age 58.

Mother has a history of hypertension and type 2 diabetes.

Social History:

Smoking history: Former smoker (1 pack/day for 20 years, quit 5 years ago).

Drinks alcohol occasionally (2-3 drinks per week).

Sedentary lifestyle, reports no regular exercise.

Diet high in sodium and fat, with low intake of fruits and vegetables.

Review of Systems:

Cardiovascular: Palpitations, lightheadedness, and dizziness. No chest pain or discomfort.

Respiratory: Mild shortness of breath with activity. No wheezing or cough.

Gastrointestinal: No nausea, vomiting, or abdominal pain.

Neurological: No syncope, confusion, or weakness.

Musculoskeletal: No joint pain or swelling.

Objective Data:

Vital Signs upon Arrival:

Blood Pressure: 138/85 mmHg

Heart Rate: 130 bpm (irregularly irregular)

Respiratory Rate: 18 breaths/min

Temperature: 36.8°C

Oxygen Saturation: 96% on room air

Weight: 110 kg (BMI 34 kg/m²)

Height: 175 cm

Physical Exam:

General: Patient appears alert but anxious. Slightly diaphoretic.

Cardiovascular:

Irregularly irregular rhythm with a heart rate of 130 bpm.

Normal S1 and S2, no murmurs or gallops heard.

Peripheral pulses are normal but slightly diminished in lower extremities.

Respiratory:

Clear breath sounds bilaterally, no wheezing or crackles.

No signs of respiratory distress.

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

Extremities:

No edema.

Normal capillary refill and peripheral pulses.

Neurological:

Alert and oriented to time, place, and person.

No focal neurological deficits.

Laboratory Results:

Electrolytes: Sodium 140 mEq/L, Potassium 4.1 mEq/L, Chloride 101 mEq/L

Creatinine: 1.4 mg/dL (slightly elevated, baseline due to CKD)

Blood Glucose: 162 mg/dL (elevated, stress hyperglycemia)

Troponin I: 0.1 ng/mL (within normal limits)

Complete Blood Count (CBC): Normal white blood cell count, hemoglobin 14.2 g/dL, hematocrit 42%

Coagulation Profile:

INR: 1.9 (due to non-compliance with warfarin therapy, slightly elevated)

Lipid Profile:

Total Cholesterol: 215 mg/dL

LDL: 135 mg/dL

HDL: 38 mg/dL

Triglycerides: 200 mg/dL

Electrocardiogram (ECG):

Irregularly irregular rhythm with a ventricular rate of 130 bpm.

No clear P waves, indicating atrial fibrillation.

Wide QRS complexes, consistent with ventricular arrhythmia.

No ST elevation or depression.

Premature ventricular complexes (PVCs) observed intermittently.

No evidence of acute ischemia or infarction.

Chest X-ray:

No acute findings. Cardiomegaly not present. No signs of pulmonary edema.

Assessment:

The patient presents with ventricular arrhythmia, likely associated with his underlying heart disease and hypertension. His previous myocardial infarction, along with poorly controlled hypertension and diabetes, increases his risk for arrhythmias. The ECG shows an irregularly irregular rhythm, with PVCs and a heart rate of 130 bpm, which suggests a ventricular arrhythmia in the setting of atrial fibrillation.

The patient's non-compliance with anticoagulation therapy (warfarin) and the elevated INR put him at an increased risk for thromboembolic events. His elevated blood glucose may be indicative of stress-induced hyperglycemia. The patient is also at risk for heart failure due to the combination of hypertension, diabetes, and previous myocardial infarction.

Plan:

Immediate Management:

IV access: Establish two large-bore IV lines for medication administration.

Monitor continuously for arrhythmias, hemodynamics, and oxygen saturation.

IV Metoprolol (5 mg every 5 minutes, up to 3 doses) to control heart rate and prevent further arrhythmias. Consider transitioning to oral beta-blockers once stabilized.

IV Amiodarone (150 mg bolus over 10 minutes) to control the ventricular arrhythmia if metoprolol is insufficient.

Electrolyte correction: Administer potassium 20 mEq IV if potassium levels fall below 3.5 mEq/L.

Anticoagulation: Transition to heparin IV to manage anticoagulation in the short-term until INR stabilizes and warfarin therapy can be resumed.

Lidocaine can be considered as an alternative antiarrhythmic in case of ventricular arrhythmia exacerbation.

Oxygen: Administer 4 L/min via nasal cannula to maintain SpO2 > 94%.

Pharmacotherapy upon Stabilization:

Oral beta-blockers: Continue metoprolol 50 mg daily to control heart rate and reduce the risk of arrhythmias.

Amiodarone: Continue oral therapy as an outpatient if the arrhythmia is refractory to beta-blockers.

Warfarin: Resume warfarin therapy with adjusted dosing to maintain an INR of 2-3 for stroke prevention in atrial fibrillation.

Aspirin 81 mg daily to prevent thromboembolic events.

Statin therapy: Continue atorvastatin 40 mg nightly to reduce cholesterol and prevent plaque progression.

ACE Inhibitor (lisinopril 20 mg daily) for blood pressure control and to reduce heart failure risk.

Lifestyle modifications: Recommend weight loss, smoking cessation, and improved dietary habits (low sodium, heart-healthy diet).

Monitor for Complications:

ECG monitoring: Continuous telemetry to monitor for arrhythmias and any progression.

Blood pressure monitoring: Ensure that the patient’s blood pressure remains well-controlled, especially with the use of beta-blockers.

Renal function: Regular monitoring of creatinine due to CKD.

Follow-up:

Cardiology follow-up within 1 week for further arrhythmia management and medication optimization.

Primary care follow-up for blood pressure, diabetes, and kidney function management.

Discussion:

This case highlights the complexity of managing ventricular arrhythmias in a patient with multiple cardiovascular risk factors. The underlying cause of his arrhythmia is multifactorial, including a history of myocardial infarction, poorly controlled hypertension, diabetes, and non-compliance with anticoagulation. Early antiarrhythmic therapy with beta-blockers and amiodarone, along with IV anticoagulation therapy, is essential to prevent further arrhythmia episodes and thromboembolic events. Long-term therapy involves beta-blockers, anticoagulation, and statin therapy, alongside lifestyle changes to mitigate the risk of future cardiovascular events.

Prognosis:
The patient's prognosis will depend on his response to antiarrhythmic therapy, adherence to medications, and management of underlying risk factors. Proper anticoagulation and blood pressure management will be critical in reducing the risk of stroke and heart failure in the long-term.