In an elderly patient with a ventricular demand (VVI) leadless pacemaker implanted for chronic atrial fibrillation with high‑grade atrioventricular block and symptomatic bradycardia, should the beta‑blocker be restarted if the patient continues to experience dizziness and near‑syncope?

Do Not Restart the Beta Blocker

In an elderly patient with a VVI leadless pacemaker for chronic atrial fibrillation with high-grade AV block who continues to experience dizziness and near-syncope, you should NOT restart the beta blocker until the cause of ongoing symptoms is identified and addressed. The pacemaker should be providing adequate ventricular rate support, so persistent symptoms suggest either pacemaker malfunction, inadequate rate programming, or another underlying issue—not inadequate rate control requiring beta blockade.

Why Symptoms Persist Despite Pacing

The VVI pacemaker provides ventricular pacing when the intrinsic ventricular rate falls below the programmed lower rate limit. If symptoms continue, consider:

• Pacemaker malfunction: Failure to capture, sensing issues, or lead problems 1, 2
• Inadequate programming: Lower rate limit set too low (typically should be ≥60-70 bpm, potentially higher in symptomatic patients) 3
• Loss of AV synchrony: VVI pacing eliminates atrial contribution to ventricular filling, which can cause "pacemaker syndrome"—fatigue, dizziness, hypotension, and reduced cardiac output 4, 5
• Chronotropic incompetence: Fixed-rate VVI pacing without rate-responsive features limits cardiac output during activity 6

Critical First Steps

Interrogate the pacemaker immediately to assess:

• Battery status and lead function
• Capture and sensing thresholds
• Percentage of ventricular pacing
• Programmed lower rate limit
• Presence of rate-responsive features

Check for pacemaker syndrome: VVI pacing in patients with intact atrial activity (even in AF) can cause hemodynamic compromise from loss of AV synchrony. This manifests as the exact symptoms your patient has—dizziness and near-syncope 4, 5.

Why Beta Blockers Are Contraindicated Here

The 2024 ESC guidelines clearly state that beta blockers are recommended for rate control in AF with LVEF >40% 3, but this assumes no pacemaker is present. Your patient already has mechanical rate control via the VVI pacemaker.

Adding a beta blocker now would:

1. Suppress any remaining intrinsic ventricular escape rhythm, making the patient completely pacemaker-dependent 7, 8
2. Risk symptomatic bradycardia if pacemaker malfunction occurs 9, 7, 8
3. Potentially worsen symptoms through negative inotropic effects and hypotension 7, 8
4. Mask the underlying problem rather than addressing it

The 2009 ACC/AHA heart failure guidelines specifically warn that bradycardia from beta blockers accompanied by dizziness or lightheadedness requires dose reduction or discontinuation 8. The 2005 guidelines note that beta blocker-induced bradycardia and heart block are particularly problematic in elderly patients 7.

The VVI Pacemaker Problem

VVI pacing is suboptimal for non-AF bradyarrhythmias and even for many AF patients 6. A 2022 Japanese study found that VVI leadless pacemakers in non-AF bradyarrhythmias (including high-grade AV block) resulted in:

• 29% readmission rate for heart failure vs. 2% with dual-chamber pacing
• Trend toward higher all-cause mortality (28% vs. 4%) 6

Even in chronic AF, the loss of any residual AV synchrony with VVI pacing can be hemodynamically significant, especially in elderly patients with reduced ventricular compliance.

Appropriate Management Algorithm

1. Interrogate pacemaker (rule out device malfunction) 2

2. Optimize pacemaker settings:

   • Increase lower rate limit to 70-80 bpm if currently lower 3, 2
   • Enable rate-responsive features if available
   • Consider increasing output if capture threshold is borderline 2

3. Assess for pacemaker syndrome:

   • If present and refractory to programming changes, consider AV node ablation with upgrade to biventricular pacing (CRT) if LVEF ≤40% 3, 10
   • For LVEF >40%, lenient rate control target of <110 bpm resting is acceptable 3, 10

4. Rule out other causes: Orthostatic hypotension, volume depletion, medication effects, neurological causes

5. Only consider rate-controlling drugs if:

   • Pacemaker is functioning properly
   • Programming is optimized
   • Patient has rapid ventricular response during AF (>110 bpm at rest) despite pacing 3
   • In this scenario, digoxin would be preferred over beta blockers in elderly patients with pacemakers, as it provides rate control without suppressing escape rhythms 9, 3

Special Consideration: Drug-Induced vs. Drug-Revealed AV Block

Recent 2025 evidence suggests that AV block associated with beta blockers is rarely truly "drug-induced" but rather "drug-revealed," unmasking underlying conduction system disease 11. The high recurrence rates of AV block after drug discontinuation (even when initially resolving) support this concept. This means:

• The beta blocker likely revealed pre-existing severe conduction disease
• Restarting it risks recurrent symptomatic bradycardia
• The pacemaker was appropriately placed for permanent conduction disease, not a reversible drug effect 11

Bottom Line

Your patient's ongoing symptoms indicate inadequate pacing therapy or pacemaker dysfunction—not inadequate pharmacologic rate control. Restarting the beta blocker before optimizing device function risks worsening symptoms and potentially dangerous bradycardia. Focus on device interrogation and programming optimization first. Only consider adding rate-controlling medication (preferably digoxin, not beta blockers) if rapid ventricular rates persist despite optimal pacing settings.