Indications for the use of permanent pacemakers have extended beyond sinus node dysfunction and atrioventricular block. The third revision of the American College of Cardiology (ACC) and the American Heart Association (AHA) guidelines for indications for permanent pacing were published in 1998. Hayes summarizes the latest indications for permanent cardiac pacing.
Improvement of hemodynamics is the newest area of interest for the use of pacing. In patients with hypertrophic obstructive cardiomyopathy with significant left ventricular outflow obstruction gradient, pacing may reduce symptoms of angina and dyspnea, and improve exercise tolerance. Long-term outcomes are less clear. Patients with symptomatic first-degree atrioventricular block, or those with type 1 second-degree atrioventricular block with hemodynamic compromise associated with atrioventricular dyssynchrony and not necessarily bradycardia, may be considered for permanent pacing.
Patients with neurally mediated syncope (defined as syncope induced by a head-up tilt test) are generally not helped by pacing because the lack of atrioventricular synchrony aggravates the peripheral vasodilation that usually accompanies this condition. However, patients with subtypes of neurally mediated syncope that occur with significant bradycardia or asystole that is greater than three seconds may benefit from pacing. The North American Vasovagal Pacemaker Study was a randomized trial that demonstrated a relative risk reduction of 85 percent for syncopal spells in patients with frequent syncope and a positive head-up tilt test result with use of a dual-chamber pacemaker.
Atrial fibrillation and atrial flutter may be controlled with dual-site atrial pacing. Pacing for the prevention of atrial fibrillation is currently investigational. Pacing after cardiac transplantation is useful in patients with sinus node dysfunction.
The author concludes that indications for permanent pacing continue to evolve. The ACC/AHA guidelines provide an update on the use of pacing to improve hemodynamic function.