What is the appropriate management plan for an 80‑year‑old with new‑onset atrial fibrillation, mild heart‑failure with preserved ejection fraction, moderate mitral regurgitation, ventricular rate 87 bpm, dyspnea, light‑headedness, and hypothyroidism on levothyroxine with persistently elevated TSH?

Management Plan for New-Onset Atrial Fibrillation with HFpEF, Mitral Regurgitation, and Hypothyroidism

Start a beta-blocker immediately for rate control, optimize levothyroxine to normalize TSH, initiate anticoagulation based on stroke risk, and aggressively manage volume status with diuretics. 1

Immediate Priorities

1. Optimize Thyroid Function First

• Increase levothyroxine dose immediately to restore euthyroid state, as elevated TSH indicates inadequate thyroid replacement and may be contributing to or exacerbating the atrial fibrillation 2
• Beta-blockers provide dual benefit by controlling heart rate AND blocking peripheral conversion of T4 to T3 in the setting of thyroid dysfunction 2
• Target TSH within normal reference range with monthly monitoring until stable 2
• Critical pitfall: Do NOT attempt cardioversion or use antiarrhythmic drugs until euthyroid state is achieved, as they are generally unsuccessful while thyroid dysfunction persists 2

2. Rate Control Strategy

Beta-blocker is the Class I, Level B recommendation for persistent or permanent AF in patients with HFpEF 1

• Start with oral beta-blocker (metoprolol, carvedilol, or bisoprolol) as first-line therapy 1
• Target resting heart rate of 60-80 bpm, with 90-115 bpm during moderate activity 3
• Assess heart rate during exercise and adjust pharmacological treatment since the patient is symptomatic with dyspnea and lightheadedness 1
• If beta-blocker alone is insufficient, add digoxin for combination therapy (Class IIa, Level B recommendation) 1
• Avoid calcium channel blockers if there is any evidence of right ventricular dysfunction given the mitral regurgitation and potential for elevated right-sided pressures 4

3. Anticoagulation Assessment

Initiate oral anticoagulation immediately based on CHA₂DS₂-VASc score calculation 2, 4:

• Age 80 years = 2 points
• Heart failure (HFpEF) = 1 point
• Total score ≥3 mandates anticoagulation regardless of thyroid status 2
• Use warfarin with target INR 2.0-3.0, or direct oral anticoagulant (DOAC) 2, 4
• Monitor INR monthly once stable if using warfarin 4
• Do NOT withhold anticoagulation based on thyroid dysfunction—use CHA₂DS₂-VASc score exclusively 2

4. Volume Management

Aggressive diuretic therapy is essential given the combination of HFpEF, mitral regurgitation, and symptomatic dyspnea 4:

• Initiate or uptitrate loop diuretic to relieve congestion 4
• Monitor for signs of volume overload at rest and during activity 4
• The mitral regurgitation in this setting is likely atrial functional MR (AFMR) due to left atrial dilatation from AF, which impairs prognosis in HFpEF 5
• Assess volume status at each visit given the hemodynamic burden 4

Rhythm Control Consideration

If symptoms persist despite adequate rate control and volume optimization, consider rhythm control strategy (Class IIa, Level C) 1, 6:

• Rhythm control may be particularly beneficial in HFpEF patients with paroxysmal or early persistent AF 6
• Amiodarone can be considered when rate control with beta-blocker or digoxin (alone or in combination) is insufficient (Class IIb, Level C) 1
• However, defer any rhythm control decisions until thyroid function is normalized (approximately 4 months after achieving euthyroid state) 2
• Catheter ablation may be considered if pharmacological rhythm control fails or is not tolerated (Class IIa, Level B) 1

Monitoring Parameters

• Weekly thyroid function tests during levothyroxine dose adjustments, then monthly once stable 2
• Heart rate at rest and with activity to guide rate control medication adjustments 1
• INR monitoring if on warfarin (weekly during initiation, monthly when stable) 4
• Symptoms of dyspnea and lightheadedness to assess adequacy of rate and volume control 1
• Exercise tolerance to determine if rhythm control strategy becomes necessary 4

Critical Pitfalls to Avoid

• Never use amiodarone if hyperthyroidism is present (risk of thyroid storm), though this patient has hypothyroidism with elevated TSH 2
• Never use digoxin as monotherapy for acute rate control—always combine with beta-blocker in HFpEF 1
• Never perform AV node ablation without first attempting pharmacological rate control (Class III: Harm) 1
• Never use IV beta-blockers or calcium channel blockers if overt congestion or hypotension is present 1
• Never delay anticoagulation while optimizing other therapies—stroke risk is immediate 2, 4

Salvage Option

If rate control cannot be achieved despite optimized medical therapy, AV node ablation with permanent pacing is reasonable (Class IIa, Level B), especially if tachycardia-mediated cardiomyopathy is suspected 1, 3, 4