What are the indications for pacemaker implantation?

Indications for Pacemaker Implantation

Permanent pacemakers are primarily indicated for symptomatic bradycardia due to sinus node dysfunction, acquired atrioventricular block, and certain fascicular blocks, with the goal of reducing symptoms, improving quality of life, and in certain patient populations, improving survival. 1, 2

Class I Indications (Definite Indications)

Complete Heart Block

• Complete heart block (permanent or intermittent) at any anatomic level with:
  • Symptomatic bradycardia 1
  • Congestive heart failure 1
  • Medical conditions requiring drugs that suppress escape pacemakers 1
  • Documented asystole ≥3.0 seconds or escape rate <40 beats/min in asymptomatic patients 1
  • Confusional states that clear with temporary pacing 1
  • Post-AV junction ablation or myotonic dystrophy 1

Second Degree AV Block

• Second degree AV block (regardless of type or site) with symptomatic bradycardia 1
• Type II second degree AV block (permanent or intermittent) even when asymptomatic 1

Bifascicular and Trifascicular Block

• Bifascicular block with intermittent complete heart block and symptomatic bradycardia 1
• Bifascicular or trifascicular block with intermittent type II second-degree AV block without symptoms 1

Sinus Node Dysfunction

• Sinus node dysfunction with documented symptomatic bradycardia 1, 2
• Bradycardia-tachycardia syndrome when drugs other than digitalis are needed 1

Post-Myocardial Infarction

• Persistent advanced second degree or complete heart block after acute MI with block in the His-Purkinje system 1
• Transient advanced AV block with associated bundle branch block 1

Class II Indications (May Be Beneficial)

• Asymptomatic complete heart block with ventricular rates ≥40 beats/min 1
• Asymptomatic type II second degree AV block 1
• Bifascicular or trifascicular block with syncope not proven due to complete heart block 1
• Markedly prolonged HV interval (>100 msec) 1
• Sinus node dysfunction with heart rates <40 beats/min without clear association between symptoms and bradycardia 1

Special Considerations

Pediatric Indications

• Second or third degree AV block with symptomatic bradycardia 1
• Advanced second or third degree AV block with exercise intolerance 1
• Congenital AV block with wide QRS escape rhythm 1
• Advanced second or third degree AV block persisting 10-14 days after cardiac surgery 1

Tachyarrhythmia Management

• Symptomatic recurrent supraventricular tachycardia when drugs fail or produce intolerable side effects 1
• Symptomatic recurrent ventricular tachycardia when other therapies are not applicable 1

Heart Failure

• Biventricular pacing (cardiac resynchronization therapy) for advanced heart failure with major intraventricular conduction defects, predominantly left bundle branch block 1, 2

Device Selection Considerations

• In older patients, dual-chamber pacemakers that maintain synchrony between atria and ventricles are preferred as they maintain the increased contribution of atrial contraction to ventricular filling 1, 2, 3
• Rate-responsive devices are generally preferred as they better simulate physiologic sinus node function 1
• Dual-chamber pacemakers have been shown to reduce reoperation rates compared to single-chamber atrial pacemakers, primarily due to development of AV block requiring device upgrade 4
• Dual-chamber pacing may reduce the risk of paroxysmal atrial fibrillation compared to single-chamber atrial pacing 4

Contraindications (Class III)

• First degree AV block without symptoms 1
• Fascicular block without AV block or symptoms 1
• Transient AV conduction disturbances without intraventricular conduction defects 1
• Sinus node dysfunction in asymptomatic patients 1
• Tachycardias that are accelerated or converted to fibrillation by pacing 1

Clinical Pearls and Pitfalls

• Temporary pacing requirement during acute myocardial infarction does not by itself constitute an indication for permanent pacing 1
• Mobitz type I (Wenckebach) second degree AV block is not benign in patients ≥45 years of age and should be considered for pacing even without symptoms 5
• Pacemaker implantation should be considered in patients with Mobitz type II AV block even when asymptomatic due to high risk of progression to complete heart block 1
• Temporary pacemakers can have significant complications (22% of patients), including electrode displacement requiring repositioning (9%), and rarely death (6%) 6
• The decision to implant a pacemaker should be based primarily on the presence of symptoms attributable to bradycardia, but certain high-risk conduction abnormalities may warrant prophylactic pacing even in asymptomatic patients 1