Indications for pacemakers

Associate Editor:

Class I

 * 1) Sinus node dysfunction with documented symptomatic bradycardia, including frequent sinus pauses that produce symptoms. In some patients, bradycardia is iatrogenic and will occur as a consequence of essential long-term drug therapy of a type and dose for which there are no acceptable alternatives.
 * 2) Symptomatic chronotropic incompetence.

Class IIa

 * 1) Sinus node dysfunction occurring spontaneously or as a result of necessary drug therapy with heart rate <40 bpm when a clear association between significant symptoms consistent with bradycardia and the actual presence of bradycardia has not been documented.

Class IIb

 * 1) In minimally symptomatic patients, chronic heart rate <30 bpm while awake.

Class III

 * 1) Sinus node dysfunction in asymptomatic patients, including those in whom substantial sinus bradycardia (heart rate <40 bpm) is a consequence of long-term drug treatment.
 * 2) Sinus node dysfunction in patients with symptoms suggestive of bradycardia that are clearly documented as not associated with a slow heart rate.
 * 3) Sinus node dysfunction with symptomatic bradycardia due to nonessential drug therapy.

Class I

 * 1) Third-degree AV block at any anatomic level associated with any one of the following conditions:
 * 2) Bradycardia with symptoms presumed to be due to AV block.
 * 3) Arrhythmias and other medical conditions that require drugs that result in symptomatic bradycardia.
 * 4) Documented periods of asystole  3.0 seconds or any escape rate <40 beats per minute (bpm) in awake, symptom-free patients.
 * 5) After catheter ablation of the AV junction.
 * 6) Postoperative AV block that is not expected to resolve.
 * 7) Neuromuscular diseases with AV block such as myotonic muscular dystrophy, Kearns-Sayre syndrome, Erb's dystrophy (limb-girdle), and peroneal muscular atrophy.
 * 8) Second-degree AV block regardless of type or site of block, with associated symptomatic bradycardia.

Class IIa

 * 1) Asymptomatic third-degree AV block at any anatomic site with average awake ventricular rates of 40 bpm or faster.
 * 2) Asymptomatic type II second-degree AV block.
 * 3) Asymptomatic type I second-degree AV block at intra- or infra-His levels found incidentally at electrophysiological study for other indications.
 * 4) First-degree AV block with symptoms suggestive of pacemaker syndrome and documented alleviation of symptoms with temporary AV pacing.

Class IIb

 * 1) Marked first-degree AV block (>0.30 second) in patients with LV dysfunction and symptoms of congestive heart failure in whom a shorter AV interval results in hemodynamic improvement, presumably by decreasing left atrial filling pressure.

Class III

 * 1) Asymptomatic first-degree AV block.
 * 2) Asymptomatic type I second-degree AV block at the supra-His (AV node) level or not known to be intra- or infra-Hisian.
 * 3) AV block expected to resolve and unlikely to recur (eg, drug toxicity, Lyme disease).

Class I

 * 1) Intermittent third-degree AV block.
 * 2) Type II second-degree AV block.

Class IIa

 * 1) Syncope not proved to be due to AV block when other likely causes have been excluded, specifically ventricular tachycardia (VT).
 * 2) Incidental finding at electrophysiological study of markedly prolonged HV interval ( 100 milliseconds) in asymptomatic patients.
 * 3) Incidental finding at electrophysiological study of pacing-induced infra-His block that is not physiological.

Class IIb

 * 1) None.

Class III

 * 1) Fascicular block without AV block or symptoms.
 * 2) Fascicular block with first-degree AV block without symptoms.

Class I

 * 1) Recurrent syncope caused by carotid sinus stimulation; minimal carotid sinus pressure induces ventricular asystole of >3 seconds' duration in the absence of any medication that depresses the sinus node or AV conduction.

Class IIa

 * 1) Recurrent syncope without clear, provocative events and with a hypersensitive cardioinhibitory response.
 * 2) Syncope of unexplained origin when major abnormalities of sinus node function or AV conduction are discovered or provoked in electrophysiological studies.

Class IIb

 * 1) Neurally mediated syncope with significant bradycardia reproduced by a head-up tilt with or without isoproterenol or other provocative maneuvers.

Class III

 * 1) A hyperactive cardioinhibitory response to carotid sinus stimulation in the absence of symptoms.
 * 2) A hyperactive cardioinhibitory response to carotid sinus stimulation in the presence of vague symptoms such as dizziness, light-headedness, or both.
 * 3) Recurrent syncope, light-headedness, or dizziness in the absence of a hyperactive cardioinhibitory response.
 * 4) Situational vasovagal syncope in which avoidance behavior is effective.