Biventricular and novel pacing mechanisms in heart failure.

Biventricular pacing, often referred to as cardiac resynchronization therapy (CRT), improves subjective and objective measures and promotes reverse ventricular remodeling in patients with chronic New York Heart Association (NYHA) class III or IV heart failure despite optimal medical therapy, QRS duration of more than 130 ms, and left ventricular ejection fraction of less than 35%. However, there are many nonresponders and other patients who do not meet criteria for CRT, limiting the efficacy of therapy. Recent investigations (eg, the REVERSE trial) have shown that patients with minimal symptoms (NYHA class I-II) can benefit from the mechanical and functional effects of CRT, specifically reverse remodeling. Ongoing investigations include the possibility of earlier intervention in the postinfarct period with CRT. Additionally, a novel pacing mechanism known as cardiac contractility modulation has also shown promise in improving remodeling of the failing heart. In this article, we review CRT's effects on reverse remodeling in an expanding patient population and as a novel pacing mechanism, its cardiac contractility modulation, and its benefits in patients with heart failure.