What are the indications for pacemaker implantation?

Indications for Pacemaker Implantation

Permanent pacemaker implantation is primarily indicated for symptomatic bradycardia, complete heart block, advanced AV block, and sinus node dysfunction with symptoms, as these conditions significantly impact mortality and quality of life when left untreated. 1

Primary Indications (Class I)

Atrioventricular Block

• Complete heart block (permanent or intermittent) with:

  • Symptomatic bradycardia (syncope, dizziness, fatigue, confusion)
  • Congestive heart failure
  • Documented periods of asystole or escape rate <40 beats/min
  • Confusional states that clear with temporary pacing
  • Post-AV junction ablation 2

• Second or third-degree AV block with:

  • Symptomatic bradycardia
  • Moderate to marked exercise intolerance 2
  • Advanced second or third-degree AV block persisting 10-14 days after cardiac surgery 2

Sinus Node Dysfunction

• Sinus node dysfunction (sick sinus syndrome) with:
  • Symptomatic bradycardia
  • Documented correlation between symptoms and bradycardia 2, 1
  • Bradycardia-tachycardia syndrome requiring antiarrhythmic drugs 2

Bifascicular and Trifascicular Block

• Bifascicular block with intermittent complete heart block and symptomatic bradycardia
• Bifascicular or trifascicular block with intermittent type II second-degree AV block 2

Special Conditions

• External ophthalmoplegia with bifascicular blocks 2
• Congenital AV block with wide QRS escape rhythm or block below the His bundle 2
• Hypersensitive carotid sinus syndrome with recurrent syncope and documented asystole >3 seconds during carotid sinus stimulation 2
• Symptomatic recurrent supraventricular tachycardia when drugs fail to control the arrhythmia 2
• Long QT syndrome with recurrent syncope or seizures, especially when refractory to beta-blockers 3

Secondary Indications (Class II)

• Asymptomatic complete heart block with ventricular rates ≥40 beats/min
• Asymptomatic second or third-degree AV block with ventricular rate <45 beats/min when awake
• Sinus node dysfunction with heart rates <40 beats/min without clear association between symptoms and bradycardia 2, 1
• Bifascicular or trifascicular block with syncope not proven due to complete heart block but with no other identifiable causes 2, 1
• Recurrent syncope with hypersensitive cardioinhibitory response without clear provocative events 2

Not Indicated (Class III)

• Asymptomatic sinus node dysfunction
• Sinus node dysfunction with symptoms clearly documented not to be associated with bradycardia
• First-degree AV block
• Asymptomatic fascicular block without AV block
• Transient AV block that returns to normal conduction within 1 week 2

Special Considerations in Children

Pacemaker indications in children are similar to adults but require:

• Greater emphasis on concurrent observation of symptoms with bradycardia
• Careful consideration in bradycardia-tachycardia syndrome requiring antiarrhythmic drugs, as medications like propranolol and amiodarone can severely depress sinus node function 2, 1

Clinical Impact and Outcomes

• Permanent pacing significantly reduces symptoms such as fatigue, dizziness, and syncope 1
• Survival rates differ based on presenting symptoms - patients with dizziness (Adams-Stokes equivalents) show better survival than those with syncope (Adams-Stokes attacks) or heart failure 4
• Pacemaker therapy reduces mortality in certain populations and prevents complications associated with bradyarrhythmias 1
• Careful monitoring is needed after implantation, as sudden death can occur despite pacing, particularly in the first year after implantation for patients with Adams-Stokes attacks 4

Pitfalls and Caveats

• Before implanting a pacemaker for hypersensitive carotid sinus syndrome, determine the relative contribution of cardioinhibitory and vasodepressor components, as pacing alone may not resolve symptoms if there is a significant vasodepressor component 2
• Late pacemaker requirement after heart transplantation may indicate transplant coronary artery disease 5
• Temporary pacemakers, while lifesaving, carry significant complication risks (22%), including electrode displacement (9%), and even death (6%) 6
• In patients with sick sinus syndrome, dual-chamber pacemakers are generally cost-effective compared to single-chamber atrial pacemakers, with an ICER of £6,506 7

The decision to implant a pacemaker should be guided by clear documentation of symptomatic bradycardia or high-risk conduction disorders that impact mortality and quality of life, with careful consideration of patient-specific factors and potential complications.