Cardiac resynchronisation therapy (CRT) aims to restore left ventricular electrical/mechanical dyssynchrony, which can underlie impaired systolic left ventricular (LV) function and congestive heart failure. Several large prospective studies were able to document clearly that chronic electrical synchronisation does improve the systolic dysfunction and ameliorates symptoms, patient functioning and prognosis. If the conventional criteria are applied, this positive response can be observed in roughly 70% of patients, depending on the definition used for ‘positive response’.
