Pathobiology of left ventricular dyssynchrony and resynchronization.

Left ventricular mechanical dyssynchrony has recently been recognized as a significant contributor to increased morbidity and mortality in some patients with congestive heart failure. Ventricular dyssynchrony compromises global cardiac mechanical efficiency, induces changes in regional hypertrophy and blood flow, and results in local alterations in myocardial protein expression. Cardiac resynchronization therapy has both immediate and long-term beneficial effects on global cardiac function, and has been shown to reduce both morbidity and mortality in heart failure patients. The effects of resynchronization on the tissue-level and molecular consequences of dyssynchrony remain unknown.