[Non-pharmacological therapy of decompensated heart failure: cardiac resynchronization therapy]

Cardiac resynchronization therapy (CRT) is a novel and effective therapy for patients with heart failure. The aim of CRT is to improve the heart's pumping efficiency by the resynchronization of the chambers. Electrical dyssynchrony shows itself as bundle branch block with prolongation of QRS >120 ms. Mechanical dyssynchrony (atrioventricular, interventricular and intraventricular) is evidenced by echocardiographic parameters. A cardioverter-defibrillator function can be included with the pulse generator in patients with high risk of sudden death. The estimate of perioperative death associated with CRT was 0.3% with a low rate of complications, similar to that seen in standard pacemaker placement. In 10% of patients there was an implant failure due to the difficulty in accessing the coronary sinus. Approximately one third of patients are non-responder with no significant improvement after implantation. The beneficial effect of CRT on soft endpoints and mortality (symptoms, NYHA class, 6-min walking test, quality of life score, ejection fraction) was demonstrated in the earliest randomized clinical trials. Current guidelines for CRT are based on inclusion and exclusion criteria in the large randomized trials that have been performed and patients with chronic atrial fibrillation are included. Unresolved issues are the identification of non-responders and the efficacy of CRT in patients with mechanical dyssynchrony without electrical dyssynchrony and in NYHA functional class I/II patients with ejection fraction < or = 35%.