2008 ACC/AHA/HRS Guidelines for Device-Based Therapy of Cardiac Rhythm Abnormalities: Clinical Implications

Dr. Liem provides a brief summary on the recently revised ACC/AHA/HRS guidelines for device-based therapy. The 2008 ACC/AHA/HRS Guidelines for Device-Based Therapy of Cardiac Rhythm Abnormalities1 are a further expansion to those published in 2002. There were significant modifications to the 2002 AHA/ACC/NASPE guidelines, mainly by incorporation of the ACC/AHA/ESC 2006 guidelines for sudden death prevention.2,3 Also importantly, these evidence-based guidelines reflect recently published data and therefore incorporate additional recommendations accordingly, with the most notable being items relating to cardiac resynchronization therapy. In the section under permanent pacemaker recommendations, there were only few modifications and additions. There were no new guidelines or alterations in the indications for sick sinus syndrome, atrioventricular (AV) block, bifascicular and trifascicular blocks, hypersensitive carotid sinus and neurocardiogenic syncope, cardiomyopathy (hypertrophic and dilated) in patients with congenital heart disease, or for pacing for prevention and termination of tachyarrhythmias. Reflective of the concern for the effect of rhythm abnormality on left ventricular (LV) dysfunction (as also outlined below), a class I pacemaker indication is noted for patients with asymptomatic persistent third-degree AV block at any site with heart rates of 40 or above in the presence of cardiomegaly or LV dysfunction. Asymptomatic complete heart black is a common scenario in patients with congenital AV blocks. In this case, bradycardia-induced LV remodeling is the key concern. One additional section refers to pacing to prevent atrial fibrillation (AF), which states that it is not indicated (thus, class III) in the absence of any other indication for pacemaker implantation. A new section discussed the choice between a single-chamber atrial pacemaker, single-chamber ventricular pacemaker, dual-chamber pacemaker, or single-lead, atrial-sensing ventricular pacemaker. A new indication section is for cardiac resynchronization therapy (CRT). The indication follows the Medicare recommendation in 2005, namely in patients with LV ejection fraction (LVEF) of less than 35% and QRS duration of greater than 0.12 seconds. Class I indication is for patients with sinus rhythm, while those with AF fall within a class IIa indication. It is important to note that in this section, patients without a QRS of > 0.12 seconds but who are likely to be ventricularly paced are considered to be a candidate for CRT with class IIb indication. With respect to implantable cardioverter-defibrillator (ICD) therapy, a section is devoted to primary prevention for sudden death. Thus, under class I indication, patients would qualify for an ICD for primary prevention of sudden death when they have an LVEF of ≤ 35% and are considered NYHA class II or III, whether the etiology is ischemic or non-ischemic. A cut-off of 30% is required in patients with NYHA class I and ischemic cardiomyopathy. Under Class IIa indications, specific conditions such as long QT syndrome, Brugada syndrome, hypertrophic cardiomyopathy, arrhythmogenic right ventricular dysplasia, cardiac sarcoidosis, giant cell myocarditis, Chagas disease, and those awaiting transplantation are included. A special section on ICD indication is also devoted to pediatric patients and patients with congenital heart disease. The guidelines are quite comprehensive and provide clear-cut indications on pacemaker and ICD implantation. These will assist in patient selection, administrative work, and staff education. The inclusion of issues affecting LV function is reflective of the intricate interaction between rhythm abnormality and heart failure, yet underscores the need for corroborative work between the two disciplines. It also underscores the importance of device-based therapy in these patients. Guidelines such as these will continue to evolve as will the field of electrophysiology, which is now closely intertwined with the field of congestive heart failure. 1. Epstein AE, DiMarco JP, Ellenbogen KA, at el. ACC/AHA/HRS 2008 guidelines for device-based therapy of cardiac rhythm abnormalities: Executive summary. Heart Rhythm 2008;5:934-955. 2. Borgreffe M, Buxton AE, Chaitman B, et al. ACC/AHA/ESC 2006 guidelines for management of patients with ventricular arrhythmias and the prevention of sudden death — Executive summary. J Am Coll Cardiol 2006;48:1064-1108. 3. Gregoratos G, Abrams J, Epstein AE, et al. ACC/AHA/NASPE 2002 guideline update for implantation of cardiac pacemaker and antiarrhythmia devices: Summary article. Circulation 2002;106:2145-2161.