Last update:
10-Dec-2008

Cardiac resynchronization therapy (CRT) has been shown to improve both the hemodynamic parameters and longterm functional capacity in patients with ventricular dysynchrony, which very often characterizes patients with heart failure. Studies have shown that CRT contributes to a significant improvement in left ventricular (LV) structure and function, improved NYHA functional class, better exercise tolerance and quality of life, and, finally, to a lower morbidity and mortality. The selection of patients for cardiac resynchronization therapy is based on clinical, electrocardiographic and echocardiographic criteria and includes NYHA class III or IV patients treated with optimal medical therapy, with a QRS duration >130 ms, EF <=35% and LVEDD >55 mm. Several clinical trials have demonstrated the safety and efficacy of the method of CRT. The majority of these trials reported a positive effect reflected in a reduction of mortality and in the incidence of readmissions during follow-up for major cardiovascular events. The main indications for inclusion in these trials were LVEF <=35%, and a QRS >120 ms. Many of these trials also showed a diminution of LV and systolic diameter or volume, even in NYHA class II patients. However, some unanswered questions still remain as regards the agreement on electrical or electromechanical dysynchrony criteria. In conclusion, CRT, either alone or in combination with an ICD system, improves symptoms, and reduces major morbidity and mortality in patients with congestive heart failure.

Key words: Biventricular pacing, Cardiac resynchronization, Congestive heart failure, Implantable cardioverter defibrillator-ICD, Ventricular dysynchrony.