Heart failure. The pacing therapy.

Several medical therapies, including digoxin, angiotensin-converting enzyme inhibitors, and beta-blockers, have reduced the number of re-hospitalizations and slowed the progression of congestive heart failure (CHF) improving survival. Despite these benefits, medical therapy frequently fails to improve quality of life. Since 1990, there has been a growing interest in using cardiac pacing as additional treatment in severe CHF. Biventricular pacing is used in CHF patients with left bundle branch block (LBBB) to improve ventricular activation sequence which may lead to a more coordinated and efficient ventricular contraction. Since its introduction in CHF in 1994, biventricular pacing has been widely applied with many clinical trials and the development of new specific technology. With the development of new technology, the left ventricular catheterization via a coronary sinus vein, increased from 56% to over 95% during the last 2 years with an acceptable number of complications. Despite encouraging acute and short-term results, pacing strategies for CHF are still limited and currently regarded as investigational. It is clear that while some patients respond remarkably, this is high variable. Clinical trials are currently underway to assess the impact of cardiac resynchronization therapy on morbi-mortality and to assess the association with ventricular defibrillation. The whole validation process of cardiac resynchronization therapy should be completed on 2004-2005. Another novel mode of pacing therapy, which may be clinically appropriate for a broader range of CHF patients irrespective of the presence of LBBB, is contractility modulation, which involves sub-threshold pacing to increase intracellular calcium and enhance inotropy.