Cardiac resynchronization therapy in congestive heart failure: The state of the art and future perspectives

Congestive heart failure (CHF) is one of the leading causes of morbidity and mortality worldwide. Up to 50% of CHF patients have intraventricular conduction disturbances such as left bundle branch block or nonspecific wide QRS complex on the body surface ECG. Intraventricular conduction delays cause dyssynchrony of the ventricles which in turn leads to regional movement abnormalities and worsening of cardiac function. Recent clinical trials have indicated that cardiac resynchronization therapy or biventricular pacing in CHF patients with left bundle branch block or wide QRS complex improves cardiac function class, exercise tolerance, maximum oxygen consumption and quality of life within the first 12 months of therapy. The number of hospitalizations and the use of intravenous medications for worsening heart failure are also reduced by this new therapy. Apart from the short to medium term clinical benefits, cardiac resynchronization therapy has not been shown to reduce overall cardiac mortality. The present article reviews the pathophysiology of ventricular dyssynchrony and evaluates the results of recent clinical trials on resynchronization therapy.