What is the disposition for a patient with complete atrioventricular (AV) block?

Management of Complete Atrioventricular Block

All patients with complete atrioventricular (AV) block require permanent pacemaker implantation, regardless of symptoms, and should be admitted to a monitored setting until pacemaker placement. 1

Initial Assessment and Stabilization

• Assess hemodynamic stability immediately:

  • If unstable (hypotension, altered mental status, chest pain, heart failure):
    • Initiate temporary transcutaneous pacing
    • Consider IV atropine 0.5mg every 3-5 minutes (maximum 3mg) as bridging therapy 1, 2
  • Monitor continuously due to risk of sudden death, especially with distal (infranodal) block 1

• Evaluate ECG characteristics:

  • Narrow QRS escape rhythm: Block likely at AV node or His bundle (better prognosis)
  • Wide QRS escape rhythm: Block likely within or below His bundle (worse prognosis) 1

Risk Stratification

• High-risk features requiring urgent intervention: 3, 1

  • Escape rhythm <40 beats/min
  • Documented asystole ≥3.0 seconds
  • Symptomatic bradycardia (syncope, near-syncope, confusion)
  • Congestive heart failure
  • Need for medications that suppress escape pacemakers

• Evaluate for potentially reversible causes: 1, 4

  • Acute myocardial ischemia (consider revascularization)
  • Electrolyte abnormalities
  • Drug toxicity (especially AV nodal blocking agents)
  • Inflammatory conditions (myocarditis, sarcoidosis)

Definitive Management

• Permanent pacemaker implantation: 3, 1

  • Class I indication for all patients with complete heart block
  • DDD or DDDR pacing mode typically preferred
  • Consider cardiac resynchronization therapy if left ventricular dysfunction is present

• Special considerations:

  • Alternating bundle branch block: Implies unstable conduction disease and requires permanent pacing due to high risk of developing complete AV block 3
  • If complete heart block occurs with acute MI: Follow specific guidelines for pacing in post-MI setting 3
  • In patients with atrial fibrillation/flutter with complete heart block: Permanent pacing indicated if bradycardia is unrelated to digitalis or drugs known to impair AV conduction 3

Disposition

1. Admit all patients with complete AV block to a monitored setting 1
2. Arrange for permanent pacemaker implantation without delay, even if patients appear stable 1
3. Continuous cardiac monitoring until pacemaker implantation due to risk of sudden death, particularly with infranodal block 1
4. Post-pacemaker implantation:
   • Routine follow-up to ensure proper device function
   • Address any underlying cardiac conditions

Pitfalls and Caveats

• Do not delay permanent pacemaker implantation even in asymptomatic patients with complete heart block, as they remain at risk for sudden death 3, 1
• Avoid AV nodal blocking agents as they may worsen the block 1, 2
• Transcutaneous pacing is only a temporary measure and should not delay definitive therapy with permanent pacemaker implantation 5
• Recognize that some cases of complete AV block may have rare etiologies (sarcoidosis, lymphoma) that require specific treatment in addition to pacing 6