What are the Guidelines for Permanent Pacemaker Implantation? In April 1998, an executive summary of a joint task force of the American College of Cardiology and the American Heart Association published updated guidelines for the implantation of cardiac pacemakers and antiarrhythmia devices. A complete summary can be found in JACC, Vol.31, No.5, April, 1998: 1175-201 and in Circulation, Vol. 97, April 7, 1998: 1325-1335. In typical ACC/AHA fashion, indications are ranked Class I, Class II, and Class III. Class I indications are those for which there is evidence and/or general agreement that pacemaker implantation is beneficial, useful, and effective. Class II indications are those where there is conflicting evidence and/or divergence of opinion as to the usefulness or effectiveness of pacemaker implant. Class III indications are conditions where there is evidence or general agreement that pacemaker implant may be harmful and where there is no benefit or effectiveness in implantation. Only the most common indications will be presented here. For further indications, please refer to the above-listed publications. Class I Indications for pacing in acquired AV block in adults include: Third-degree AV block at any anatomic level associated with: Bradycardia with symptoms presumed to be AV block; Arrhthymias that require drugs that result in symptomatic bradycardia; Documented asystole > 3 seconds or an escape rate < 40 bpm in awake, symptom-free patients; Following catheter ablation of the AV junction; Postoperative AV block not expected to resolve; Second-degree AV block regardless of site or type of block with associated symptomatic bradycardia Class II indications for pacing in acquired AV block include: Asymptomatic third-degree AV block at any anatomic site with average awake ventricular rates of 40 bpm or faster; Asymptomatic type II second-degree AV block; Asymptomatic type I second-degree AV block at intra- or infra-His levels found incidentally; First-degree AV block with symptoms suggestive of pacemaker syndrome Class I indications for Pacing in Sinus Node Dysfunction (SND) include: Sinus node dysfunction with documented symptomatic bradycardia or symptomatic sinus pauses; Symptomatic chronotropic incompetence. Class II indications for pacing in SND include: SND occurring spontaneously or as a result of necessary drug therapy, with heart rate < 40 bpm when a clear association between symptoms and bradycardia has been documented Chronic heart rates below 30 bpm in awake minimally symptomatic patients Class I Indications for Pacing in Hypersensitive Carotid Sinus Syndrome include: Recurrent syncope caused by carotid sinus stimulation; Minimal carotid sinus pressure inducing ventricular asystole > 3 seconds; Class II indications for pacing in Hypersensitive Corotid Sinus Syndrome include: Recurrent syncope without clear provocative events and with a hypersensitive cardioinhibitory response. Syncope of unknown etiology when abnormal sinus node dysfunction is identified at electrophysiology studies