Guidelines for implantation of cardiac pacemakers have been established by a task force formed jointly by the American College of Cardiology, the American Heart Association, and the Heart Rhythm Society (ACC/AHA/HRS) [1,2]. Although there are occasional cases that cannot be categorized according to these guidelines, they are, for the most part, all-encompassing and have been widely endorsed. Similar and concordant guidelines have also been established by the European Society of Cardiology .
Some indications for permanent pacing are relatively certain or unambiguous, while others require considerable expertise and judgment. It is helpful to divide the indications for pacemaker implantation into three specific categories, or classes, as defined by the ACC/AHA/HRS guidelines [1,2]:
●Class I – Conditions in which permanent pacing is definitely beneficial, useful, and effective. In such conditions, implantation of a cardiac pacemaker is considered acceptable and necessary, provided that the condition is not due to a transient cause.
●Class II – Conditions in which permanent pacing may be indicated but there is conflicting evidence and/or divergence of opinion; class IIA refers to conditions in which the weight of evidence/opinion is in favor of usefulness/efficacy, while class IIB refers to conditions in which the usefulness/efficacy is less well established by evidence/opinion.
●Class III – Conditions in which permanent pacing is not useful/effective and in some cases may be harmful.