When is an Automated Implantable Cardioverter-Defibrillator (AICD) with pacemaker recommended over an AICD only?

When to Use AICD with Pacemaker vs. AICD Only

An AICD with pacemaker functionality (dual-chamber device) is recommended over an AICD-only device when patients have an indication for bradycardia pacing, require antitachycardia pacing for VT termination, or need cardiac resynchronization therapy. 1

Indications for AICD with Pacemaker

Definite Indications (Class I)

• Symptomatic sinus node dysfunction requiring atrial pacing 1
• Documented second- or third-degree AV block requiring pacing 1
• Sustained pause-dependent ventricular tachycardia, with or without QT prolongation 1
• Bradycardia limiting the use of necessary beta-blockers or other negative chronotropic medications 1

Reasonable Indications (Class IIa)

• Bradycardia-induced or pause-dependent ventricular tachyarrhythmias (such as in long QT syndrome with torsades de pointes) 1
• High-risk patients with congenital long-QT syndrome who require both defibrillation and pacing capabilities 1

Possible Indications (Class IIb)

• Documented history of atrial arrhythmias (but not permanent atrial fibrillation) where atrial pacing may be beneficial 1
• Hypertrophic cardiomyopathy with significant resting or provocable left ventricular outflow tract gradient where AV synchrony is important 1

When AICD-Only is Appropriate

• No indication for bradycardia pacing and no anticipated need for pacing in the future 1
• Permanent or longstanding persistent atrial fibrillation with no plans to restore sinus rhythm 1
• Conditions likely to result in VF rather than monomorphic/polymorphic VT without bradycardia-induced mechanisms (e.g., idiopathic ventricular fibrillation, Brugada syndrome, catecholaminergic polymorphic VT, short QT syndrome) 1

Clinical Evidence and Considerations

• In the MADIT-II trial, approximately 5.2% of patients with post-MI reduced ejection fraction required pacemaker or CRT implantation during a median follow-up of 20 months, with symptomatic sinus bradycardia being the most common indication (37%) 2

• Risk factors for subsequent pacemaker need include:

  • PR interval >200 ms (HR = 3.07)
  • Prior CABG (HR = 6.88) 2

• The DAVID trial demonstrated that unnecessary dual-chamber pacing (DDDR-70) in patients without pacing indications was associated with worse outcomes compared to minimal ventricular backup pacing (VVI-40), highlighting the importance of appropriate device selection 3

Subcutaneous ICD Considerations

• Subcutaneous ICDs should NOT be implanted in patients with:

  • Indications for bradycardia pacing
  • Need for cardiac resynchronization therapy
  • Requirement for antitachycardia pacing for VT termination 1

• Subcutaneous ICDs are recommended (Class I) for patients who:

  • Meet criteria for an ICD
  • Have inadequate vascular access or high infection risk
  • Have no need for pacing functions 1

Practical Algorithm for Decision-Making

1. Assess for pacing indications:

   • Evaluate for symptomatic bradycardia, conduction disorders, or pause-dependent arrhythmias 1
   • Review ECG for PR prolongation (>200 ms) or other conduction abnormalities 2

2. Consider cardiac condition:

   • Patients with certain conditions (long QT syndrome, hypertrophic cardiomyopathy) may benefit from dual-chamber devices 1
   • Assess for atrial arrhythmias that might benefit from atrial pacing 1

3. Evaluate future pacing needs:

   • Consider risk factors for developing bradycardia (medications, comorbidities) 1
   • Weigh the morbidity of potential future upgrade procedures against initial dual-chamber implantation 1

Common Pitfalls to Avoid

• Unnecessary dual-chamber device implantation in patients without pacing indications can lead to increased complications and potentially worse outcomes 3

• Failure to recognize existing or potential bradycardia requiring pacing support, particularly in patients on beta-blockers or other negative chronotropic agents 1

• Implanting a subcutaneous ICD in patients who may develop a need for pacing, necessitating a future system replacement 1