Indications for Bradycardia Pacing:

AHA/ACC Guidelines(49):

Acquired A/V block in Adults

Class I: There is general agreement that permanent pacemakers should be implanted.

a) Complete heart block, permanent or intermittent, at an anatomic level associated with any on of the following complications:

• Symptomatic bradycardia. In the presence of complete heart block symptoms must be presumed to be due the heart block unless proved otherwise
• Congestive heart failure
• Ectopic rhythms and other medical conditions that require drugs that suppress the automaticity of escape rhythms and result in symptomatic bradycardia.
• Documented periods of asystole >= 3.0 s or any escape rate <40/min. in symptom free patients
• Confusional states that clear with temporary pacing
• Post A/V junctional ablation, myotonic dystrophy

b) Second degree A/V block permanent or intermittent, regardless of the type or the site of the block, with symptomatic bradycardia.

c) Atrial fibrillation, Atrial flutter and rare cases of SVT with complete or advanced A/V block, bradycardia and any of the conditions in A1. The bradycardia must be unrelated to digitalis or drugs known to impair A/V conduction.

Class II: Conditions in which permanent pacemakers are frequently used but there is some divergence of opinion about whether they are needed.

• Asymptotic complete heart block, permanent or intermittent, at any anatomic site, with ventricular rates of 40/min. or faster
• Asymptomatic type ll second degree block, permanent or intermittent
• Asymptomatic type I second degree block at intra-His or infra-His levels.

Class III: Conditions in which there is general agreement that pacemakers are not necessary.

• First degree A/V block
• Asymptomatic type 1 second degree A/V block at the supra-his level.

AV Block Associated with Myocardial Infarction:

Class I: There is general agreement that permanent pacemakers should be implanted.

• Persistent advanced second degree A/V block or complete heart block after acute myocardial infarction with block in he His-Purkinje system
• Patients with transient advanced A/V block and associated bundle branch block

Class II: Conditions in which permanent pacemakers are frequently used but there is some divergence of opinion about whether they are needed.

• Patients with persistent advanced block in the A/V node

Class III: Conditions in which there is general agreement that pacemakers are not necessary.

• Transient A/V conduction disturbances in the absence of intraventricular conduction defects
• Transient A/V block in the presence of isolated left anterior hemiblock
• Acquired left anterior hemiblock in the absence of A/V block.

Bifasicular and Trifasicular Block (chronic)

Class I: There is general agreement that permanent pacemakers should be implanted.

• Bifasicular block with intermittent complete heart block associated with symptomatic bradycardia
• Bifasicular or Trifasicular block with intermittent type ll second degree A/V block without symptoms attributable to the hear block.

Class II: Conditions in which permanent pacemakers are frequently used but there is some divergence of opinion about whether they are needed.

• Bifasicular or trifasicular block with syncope that is not proved to be due to complete heart block, but other possible causes for syncope are not identifiable
• Markedly prolonged HV (>100ms)
• Pacing-induced infra-His block

Class III: Conditions in which there is general agreement that pacemakers are not necessary.

• Fasicular block without A/V block or symptoms
• Fasicular block with first degree block without symptoms

Sinus Node Dysfunction:

Class I: There is general agreement that permanent pacemakers should be implanted.

• Sinus node dysfunction with documented symptomatic bradycardia. In some patients this will occur as a consequence of long-term (essential) drug therapy of type and dose for which there are no acceptable alternatives.

Class II: Conditions in which permanent pacemakers are frequently used but there is some divergence of opinion about whether they are needed.

• Sinus node dysfunction occurring spontaneously or as a result of necessary drug therapy, with heart rates <40/min. when a clear association between significant symptoms consistent with bradycardia and the actual presence of bradycardia has not been documented.

Class III: Conditions in which there is general agreement that pacemakers are not necessary.

• Sinus node dysfunction in asymptomatic patients including those in whom substantial sinus bradycardia (heart rate < 40/min.) is a consequence of long-term drug treatment
• Sinus node dysfunction in patients in whom symptoms suggestive of bradycardia are clearly documented not to be associate with a slow heart rate.

Hypersensitive Carotid Sinus and Neurovascular Syndromes

Class I: There is general agreement that permanent pacemakers should be implanted.

• Recurrent syncope associates with clear, spontaneous events provoked by carotid sinus stimulation; minimal carotid sinus pressure induces asystole of >3 sec. duration in the absence of a medication that depresses the sinus node or A/V node

Class II: Conditions in which permanent pacemakers are frequently used but there is some divergence of opinion about whether they are needed.

• Recurrent syncope without clear, provocative events and with a hypersensitive cadrioinhibitory response.
• Syncope with associated bradycardia reproduced by a head-up tilt with or without isoproterenol or other forms of provocative maneuvers and in which a temporary pacemaker and second provocative test can establish the likely benefits of a permanent pacemaker

Class III: Conditions in which there is general agreement that pacemakers are not necessary.

• A hyperactive cardioinhibitory response to carotid sinus stimulation in the absence of symptoms.
• Vague symptoms, such s dizziness or light-headedness or both, with a hyperactive cardioinhibitory response to carotid sinus stimulation.
• Recurrent syncope, light-headedness or dizziness in the absence of a cardioinhibitory response.

Indications for pacing not covered by the AHA/ACC recomendations:

There are new indications(50) that include:

• The prevention of atrial fibrillation(51)(52)
• Improving cardiac function in hypertrophic cardiomyopathy(53)
• Improving cardiac function in Congestive heart failure with four chamber pacing(54)
• Monitoring for patients with recurrent syncope
• RF ablation and pacemaker/defibrillators(55)