What are the indications for pacemaker implantation?

Indications for Pacemaker Implantation

Pacemaker implantation is definitively indicated for complete heart block with symptomatic bradycardia, second-degree AV block type II (even when asymptomatic), and sinus node dysfunction with documented symptomatic bradycardia. 1

Class I Indications (Definitive - General Agreement Required)

Atrioventricular (AV) Block

• Complete (third-degree) heart block with symptomatic bradycardia, congestive heart failure, or requiring medications that suppress escape rhythms 1
• Second-degree AV block type II, regardless of symptoms 1
• Second-degree AV block with symptomatic bradycardia 1
• Advanced second- or third-degree AV block associated with ventricular dysfunction or low cardiac output 2

Sinus Node Dysfunction

• Documented symptomatic bradycardia - the key is correlation of symptoms (syncope, presyncope, dizziness) with bradycardia on ambulatory monitoring or implantable loop recorder 2, 1
• Bradycardia-tachycardia syndrome requiring antiarrhythmic drugs (other than digitalis) that cause symptomatic bradycardia 2

Bifascicular/Trifascicular Block

• Intermittent complete heart block with symptomatic bradycardia 1
• Intermittent type II second-degree AV block without symptoms 1

Post-Myocardial Infarction

• Persistent advanced second-degree or complete heart block 1
• Transient advanced AV block with associated bundle branch block 1

Pediatric Patients

• Second- or third-degree AV block with symptomatic bradycardia 1
• Advanced second- or third-degree AV block with moderate to marked exercise intolerance 2
• Congenital AV block with wide QRS escape rhythm or block below the His bundle 2
• Advanced AV block persisting 10-14 days after cardiac surgery 2

Special Indications

• Symptomatic recurrent supraventricular or ventricular tachycardia when other therapies have failed or are not applicable 1
• Recurrent syncope from carotid sinus hypersensitivity with spontaneous or provoked stimulation 1

Class II Indications (Frequently Used but Some Divergence of Opinion)

Asymptomatic Conduction Disease

• Asymptomatic complete heart block with ventricular rates ≥40 beats/min 1
• Asymptomatic type II second-degree AV block 1

Bifascicular Block with Syncope

• Syncope not definitively proven due to complete heart block when other causes excluded 1
• Markedly prolonged HV interval (>100 msec) on electrophysiology study 1

Pediatric Class II

• Bradycardia-tachycardia syndrome requiring antiarrhythmic drugs 2
• Asymptomatic second- or third-degree AV block with ventricular rate <45 beats/min when awake 2
• Complete AV block with average ventricular rate <50 beats/min when awake 2
• Long QT syndrome 2

Class III Indications (Contraindications - General Agreement Against)

Do not implant pacemakers for: 1

• First-degree AV block without symptoms
• Fascicular block without AV block or symptoms
• Transient AV conduction disturbances without intraventricular conduction defects
• Asymptomatic sinus node dysfunction
• Tachycardias that are accelerated or converted to fibrillation by pacing

Special Considerations for Device Selection

Biventricular Pacing (Cardiac Resynchronization Therapy)

• Advanced heart failure with major intraventricular conduction defects, predominantly left bundle branch block 1
• This represents a distinct indication beyond traditional bradycardia pacing 3

Pacing Mode Selection

When choosing between single-chamber versus dual-chamber pacing, consider: 2

• Dual-chamber pacing is preferred in older patients to maintain AV synchrony and atrial contribution to ventricular filling 4
• Avoid ventricular-only pacing if it causes pacemaker syndrome (loss of AV synchrony causing symptoms) 2
• For sinus node dysfunction with intact AV conduction, atrial pacing (AAI mode) is appropriate 2

Important Caveats

• Age-dependent heart rate criteria: A heart rate of 45 bpm may be normal in an adolescent but represents profound bradycardia in a newborn 2
• Correlation is critical: Symptoms must be documented to occur simultaneously with bradycardia, not just both present at different times 2
• Exclude reversible causes: Medications, electrolyte abnormalities, sleep apnea, neurocardiogenic mechanisms, and seizures must be ruled out before attributing symptoms to intrinsic conduction disease 2
• Right ventricular apical pacing may be harmful long-term, potentially increasing atrial fibrillation and heart failure risk 3, 5