What are the current guidelines for pacing and cardioversion?

Current Guidelines for Pacing and Cardioversion

Cardiac pacing and cardioversion should be implemented according to specific evidence-based guidelines that prioritize reducing morbidity and mortality while improving quality of life.

Cardiac Pacing Guidelines

Indications for Permanent Pacing

Sinus Node Dysfunction

• Permanent pacing is indicated for symptomatic sinus node dysfunction, including bradycardia-tachycardia syndrome, when symptoms are clearly correlated with bradyarrhythmia 1
• Atrial-based pacing (AAI or DDD) is preferred over ventricular pacing (VVI) as it significantly reduces stroke risk (HR: 0.81) and atrial fibrillation (HR: 0.80) 1
• The DANPACE study showed that DDDR pacing is associated with lower incidence of paroxysmal AF than AAIR pacing 1

Atrioventricular Block

• Permanent pacing is indicated for third-degree and advanced second-degree AV block with symptomatic bradycardia, asystole >3 seconds, or escape rhythm <40 bpm 1
• Pacing prevents recurrence of syncope and improves survival in patients with AV block 1
• For first-degree AV block and type I second-degree AV block with marked PR prolongation, dual-chamber pacing may provide symptomatic and functional improvement 1

Pacing Mode Selection

• For sinus node dysfunction, dual-chamber pacing (DDD) is preferred over single-chamber ventricular pacing (VVI) to reduce atrial fibrillation, signs of heart failure, and improve quality of life 2
• In patients with AV block who have normal sinus function, DDD pacing is preferred to maintain AV synchrony 1
• Patients with chronic atrial fibrillation should receive ventricular-based pacing (VVI/R) 1

Cardiac Resynchronization Therapy (CRT)

• CRT is indicated for heart failure patients with LVEF ≤35%, NYHA class III-IV symptoms despite optimal medical therapy, and QRS duration ≥120 ms (particularly with left bundle branch block) 1
• Biventricular pacing is the preferred mode, though LV pacing alone may be acceptable in selected patients 1
• For patients with a conventional pacemaker who develop severe LV dysfunction (LVEF ≤35%) and NYHA class III symptoms, upgrading to biventricular pacing is indicated 1

Special Considerations

• Patients with hypertrophic obstructive cardiomyopathy may benefit from right ventricular apical pacing in DDD mode to induce left bundle branch block and improve hemodynamics 1
• In patients with long QT syndrome, AAI/DDD pacing at sufficiently high rates may suppress ventricular tachyarrhythmias 1
• Flecainide can increase pacing thresholds and should be used with caution in patients with pacemakers 3

Cardioversion Guidelines

Electrical Cardioversion

• Synchronized electrical cardioversion is the treatment of choice for hemodynamically unstable atrial fibrillation 1
• Biphasic energy is more effective than monophasic energy, particularly in patients with large body surface area (>2.05 m²) 4
• For patients with implanted pacemakers or defibrillators, special precautions are needed during cardioversion 5:
  • Position cardioversion pads/paddles as far from the device as possible
  • Use anterior-posterior pad placement when possible
  • Use the lowest effective energy
  • Check device function after cardioversion

Internal Cardioversion

• Implantable atrial defibrillators have been developed but have limited utility due to patient discomfort at energies >1J 1
• These devices may be considered for patients with infrequent episodes of poorly tolerated AF who are also candidates for ventricular defibrillators 1

Post-Cardioversion Management

• After DC cardioversion in patients with pacemakers, careful evaluation of pacing thresholds is essential as selective ventricular threshold increases can occur 5
• High-output pacing should be available immediately after cardioversion to ensure consistent capture, particularly in pacemaker-dependent patients 5

Common Pitfalls and Caveats

• Failure to recognize reversible causes of bradyarrhythmias (drug effects, electrolyte disturbances, ischemia) before permanent pacemaker implantation 1
• Inappropriate use of ventricular pacing in patients with sinus node dysfunction, which increases risk of atrial fibrillation and heart failure 2
• Overlooking the need for device interrogation and reprogramming after cardioversion in patients with implanted devices 5
• Not considering upgrade to CRT in patients with conventional pacemakers who develop heart failure and LV dysfunction 1

By following these evidence-based guidelines, clinicians can optimize outcomes for patients requiring cardiac pacing or cardioversion, reducing morbidity and mortality while improving quality of life.