What is the best course of action for a 75-year-old female patient with a 5-year history of atrial fibrillation, currently experiencing episodes of rapid and irregular heartbeat, dizziness, and blurring of vision, with normal blood pressure, tachycardia, and on a medication regimen including telmisartan, febuxostat, sitagliptin, clopidogrel, carvedilol, rosuvastatin, metformin, and amlodipine?

Immediate Management of Atrial Fibrillation with Rapid Ventricular Response

This patient requires immediate rate control with intravenous beta-blockers, followed by optimization of her chronic oral beta-blocker therapy, and urgent evaluation for stroke risk given her symptoms of dizziness and visual changes. 1

Critical Initial Assessment

Evaluate for hemodynamic instability and stroke immediately. The combination of dizziness and blurring of vision in a 75-year-old with AF raises concern for:

• Hypoperfusion from inadequate rate control (though BP is currently 120/80) 2
• Acute stroke or TIA (visual changes are a red flag) 3
• Rate-related cardiac ischemia 3

Document the rhythm with 12-lead ECG to confirm AF with rapid ventricular response versus other arrhythmias, measure QT interval (important given her medications), and assess for ischemic changes 3

Immediate Rate Control Strategy

Administer IV metoprolol 2.5-5 mg over 2 minutes for immediate rate control since she is hemodynamically stable (BP 120/80) but symptomatic with heart rate of 90 bpm at rest 1. The target heart rate is 80-110 bpm at rest 1.

Reassess after 5 minutes and repeat IV metoprolol doses (up to 3 total) as needed to achieve adequate rate control 1. Metoprolol is effective within 5 minutes and controls rate both at rest and during exercise 1.

Why Beta-Blockers First

• She is already on carvedilol chronically, indicating beta-blockers are tolerated 1
• Beta-blockers are Class I (Level A) first-line agents for rate control in AF 1
• IV beta-blockers are preferred over amiodarone for rate control in stable patients 1

Critical Safety Concern: Current Medication Regimen

This patient is NOT adequately anticoagulated. She is only on clopidogrel (an antiplatelet agent), which is insufficient for stroke prevention in AF 3.

Calculate her stroke risk immediately:

• Age 75 years = 2 points
• Female = 1 point
• Likely hypertension (on telmisartan and amlodipine) = 1 point
• Minimum CHA₂DS₂-VASc score = 4 points 3

She requires oral anticoagulation with a vitamin K antagonist (INR 2.0-3.0) or direct oral anticoagulant, NOT just clopidogrel 3. This is a Class I (Level A) recommendation for patients with multiple stroke risk factors 3.

Optimization of Chronic Rate Control

Increase her home carvedilol dose since she is experiencing breakthrough rapid ventricular response despite being on chronic beta-blocker therapy 1. Consider increasing to 25-100 mg twice daily equivalent dosing 1.

If beta-blocker alone is inadequate, add digoxin as the second drug (Class I, Level B recommendation) for synergistic AV nodal blockade 1. The combination is more effective than either agent alone 1.

NEVER combine more than two of the following: beta-blocker, digoxin, and amiodarone due to risk of severe bradycardia, third-degree AV block, and asystole 1.

Evaluation for Cardioversion

Do NOT pursue immediate cardioversion for several reasons:

• She has known AF for 5 years (likely persistent or permanent) 3
• Duration >48 hours requires either 3 weeks of therapeutic anticoagulation OR transesophageal echocardiography to exclude LA thrombus before cardioversion 3
• She is currently inadequately anticoagulated 3
• Rate control strategy is appropriate for her age and comorbidities 3, 4

If cardioversion is considered later, she would need:

• Therapeutic anticoagulation for at least 3 weeks prior 3
• Consider amiodarone pretreatment to improve success and prevent immediate recurrence 1
• Continued anticoagulation indefinitely afterward given her high stroke risk 3

Workup for Precipitating Factors

Assess for reversible causes of AF with RVR:

• Thyroid function tests (she is on multiple medications that could affect thyroid) 3
• Electrolytes, particularly potassium and magnesium 3
• Troponin if concern for acute coronary syndrome (though not universally required in recurrent paroxysmal AF similar to prior episodes) 2
• Chest X-ray to evaluate for heart failure or pulmonary disease 3
• Echocardiogram if not recently performed to assess for valvular disease, LV function, and atrial size 3

Neurological Evaluation

Urgent neurological assessment for the visual changes and dizziness is mandatory:

• These symptoms could represent TIA or stroke 3
• 70% of strokes in AF patients occur when anticoagulation is stopped or subtherapeutic 3
• She is currently inadequately anticoagulated with only clopidogrel 3

If stroke/TIA is confirmed, this changes anticoagulation urgency - she would need immediate therapeutic anticoagulation (likely with heparin bridge) 3.

Disposition and Follow-Up

Admit for observation if:

• Visual changes or dizziness persist or worsen 2
• Rate control cannot be achieved in the ED 2
• Troponin is elevated 2
• New heart failure or ischemia is identified 3, 2

Discharge is appropriate only if:

• Rate control achieved (HR 80-110 at rest) 1
• Neurological symptoms fully resolved and stroke ruled out 2
• Appropriate anticoagulation initiated 3
• Close cardiology follow-up arranged within 1-2 weeks 3

Key Pitfalls to Avoid

Do not use calcium channel blockers (diltiazem/verapamil) in addition to her current regimen - she is already on amlodipine (a dihydropyridine), and adding non-dihydropyridine calcium channel blockers to beta-blockers increases risk of heart block 3, 1.

Do not stop anticoagulation once initiated - most strokes in AF occur when anticoagulation is interrupted or subtherapeutic 3.

Do not use digoxin as sole agent for rate control in paroxysmal AF (Class III recommendation) 3.

Do not dismiss the visual symptoms - they require urgent evaluation and may represent the most serious complication of inadequate anticoagulation 3.