Implantable devices for management of chronic heart failure: defibrillators and biventricular pacing therapy

With chronic heart failure already an epidemic in the USA, its prevalence is expected to rise significantly in the future. Despite improved survival with pharmacologic therapy, the morbidity and mortality of patients with heart failure remain high. The purpose of this review, therefore, is to present recent data on the non-pharmacologic, device-based treatment of patients with chronic heart failure.

The implantable cardioverter-defibrillator has become standard treatment for the prevention of sudden, arrhythmic death. Recent well-designed clinical trials have led to device-based therapy as an important component in the management of patients with systolic left ventricular dysfunction (resulting from both ischemic and non-ischemic etiologies) and symptomatic chronic heart failure. Implantable cardioverter-defibrillator therapy alone (without biventricular pacing) results in a significant reduction in the overall mortality of patients with mild and moderate heart failure. Biventricular pacing (or cardiac resynchronization therapy) with or without a back-up implantable cardioverter-defibrillator, compared with optimal pharmacologic therapy, improves symptoms, quality of life, exercise tolerance, left ventricular function, and the survival of patients with advanced heart failure, a left ventricular ejection fraction of 35% or less, and intraventricular conduction delays (QRS > 120 ms), although up to approximately 30% of patients do not respond to cardiac resynchronization therapy. Ongoing and planned studies should clarify which patients are most likely to respond to cardiac resynchronization therapy and elucidate its role in those with a normal (< 120 ms) QRS (approximately 70% of patients with heart failure).

Device therapy (implantable cardioverter-defibrillator and cardiac resynchronization therapy) should be considered an integral, but adjunctive, part of the management of patients with chronic heart failure who are receiving appropriate medical therapy. The type of device used will depend on the individual patient's clinical characteristics.