[Optimized CRT programming: relevance and practical application].

Cardiac resynchronization therapy (CRT) can result in significant clinical improvement in patients with congestive heart failure. Non-response to CRT might be attributable to suboptimal programming. Follow-up has to ensure effective left ventricular (LV) stimulation at rest and also sufficient exercise-dependent atrial rates. Rate adaptive pacing is required in case of chronotropic incompetence. Specific algorithms may help to restore biventricular pacing or the enhance biventricular pacing rate when intrinsic AV conduction occurs, e.g., during intermittent atrial fibrillation. An individual adaptation of the AV interval is essential to achieve maximal benefit from resynchronization. Optimized AV interval programming synchronizes atrial and ventricular contraction, maximizing the atrial contribution to LV diastolic filling and preventing presystolic mitral regurgitation. Interventricular synchrony and LV contraction might be further harmonized by VV interval adaptation, although the impact of VV optimization on CRT outcome is still under debate. Non-invasive methods of AV and VV interval optimization by electro- and echocardiography are discussed.