What is the optimal treatment for a 71-year-old male with intermittent atrial fibrillation, currently taking atenolol (beta-blocker) 25 mg and one baby aspirin (acetylsalicylic acid) daily?

Management of Intermittent Atrial Fibrillation in a 71-Year-Old Male

This patient requires oral anticoagulation with a vitamin K antagonist or direct oral anticoagulant (DOAC) due to his age and risk of thromboembolism, while continuing beta-blocker therapy for rate control.

Stroke Risk Assessment

The patient's profile indicates significant stroke risk factors:

• Age 71 years (major risk factor)
• Intermittent atrial fibrillation

Based on the CHA₂DS₂-VASc scoring system, this patient has at least 2 points (age ≥ 75 years = 2 points) which places him at high risk for thromboembolism 1.

Anticoagulation Therapy

Recommended Approach:

1. Initiate oral anticoagulation therapy:

   • Preferred: Direct oral anticoagulant (DOAC) due to superior safety profile compared to vitamin K antagonists 1
   • Alternative: Warfarin with target INR 2.0-3.0 if DOACs are contraindicated 2

2. Discontinue aspirin monotherapy:

   • Current aspirin monotherapy is inadequate for stroke prevention at this age
   • Research shows aspirin has no discernible protective effect against stroke in AF and may even increase risk in elderly patients 3
   • Class I recommendation indicates oral anticoagulation for patients aged ≥75 years 2

Rate Control Management

Current and Recommended Approach:

1. Continue beta-blocker therapy:

   • Current dose of atenolol 25mg is at the lower end of therapeutic range
   • Consider titrating atenolol to 50mg daily if heart rate is not adequately controlled 4
   • Beta-blockers are recommended as first-line agents for rate control in AF (Class I recommendation) 2

2. Monitoring parameters:

   • Target heart rate at rest: 60-80 bpm
   • Target heart rate during moderate exercise: <110 bpm
   • Monitor for symptoms of bradycardia, especially with dose increases

Rhythm Control Considerations

For this patient with minimal symptoms (only palpitations):

• Rate control strategy is appropriate as first-line approach
• Rhythm control with cardioversion or antiarrhythmic drugs could be considered if symptoms worsen despite adequate rate control
• Class IIa recommendation supports immediate electrical cardioversion only if associated with acute MI, symptomatic hypotension, angina, or cardiac failure 2

Follow-up Plan

1. Anticoagulation monitoring:

   • If warfarin is chosen: Check INR weekly during initiation, then monthly when stable 2
   • If DOAC is chosen: Regular assessment of renal function and medication adherence 1

2. Rate control assessment:

   • Evaluate heart rate response both at rest and during exercise
   • Consider combination therapy with digoxin if beta-blocker alone is insufficient (Class IIa) 2

Important Caveats

• Do not use aspirin as monotherapy for stroke prevention in AF patients of this age group 3
• Do not use digoxin as sole agent for rate control (Class III recommendation) 2
• Reevaluate need for anticoagulation at regular intervals (Class I recommendation) 2
• Do not discontinue anticoagulation if sinus rhythm is restored, as the risk of thromboembolism persists 1

The evidence strongly supports transitioning this patient from aspirin to oral anticoagulation while maintaining beta-blocker therapy for rate control, as this approach will significantly reduce his risk of stroke and associated mortality.