[Cardiac resynchronization therapy-current status and future perspectives]

Cardiac resynchronization therapy (CRT) by pacemakers is a new therapeutic principle in the treatment of advanced heart failure. It aims to correct the intracardiac conduction disturbances that are frequently associated with left ventricular dysfunction and thus reduce their negative hemodynamic consequences. In early studies on CRT, acute improvement in cardiac hemodynamics could be shown. Nowadays it is accepted that cardiopulmonary exercise capacity is also improved in the long term with CRT. In addition, reduction of functional mitral regurgitation and reverse left ventricular remodeling have been demonstrated in the majoriy of patients. The results of recent studies demonstrate a reduction in mortality and hospitalizations by CRT. The results of these trials have led to an accepted indication for CRT as an adjunct treatment in heart failure in the updated US guidelines. However, about 30% of patients undergoing device implantation according to currently accepted implant criteria will show no substantial improvement with CRT. Therefore, other indicators to identify therapy responders must be developed in the future, e.g. by using echocardiographic techniques. Moreover, it is yet unclear in how many patients a defibrillator backup is necessary for a CRT patient. This article summarizes the current status of CRT with regard to indications and clinical results. In addition, unresolved issues are discussed and potential developments for the future highlighted.