Cardiac resynchronization therapy in heart failure. Doubts and certainties.

Cardiac resynchronization therapy (CRT) is an effective and useful electrical treatment for appropriately selected heart failure patients with complete left bundle branch block, even for those with mild symptoms. It has been calculated that 3-12% of heart failure patients could benefit from a CRT device. According to the results of a series of trials, biventricular pacing improves quality of life and haemodynamic parameters and this is associated with a reduction in heart failure hospitalizations and mortality. The efficacy of CRT has been proven by a series of randomized controlled studies, and consensus guidelines now give precise recommendations for selecting candidates for CRT not only among patients with moderate to severe heart failure, but also among patients with mild heart failure. Despite some uncertainties concerning a series of issues (selection of candidates, prediction of response, phrenic nerve stimulation, optimization of device programming), CRT is now an accepted treatment for selected patients with heart failure and specific indications are included in consensus guidelines for heart failure treatment. Devices for CRT have a relatively high upfront cost, but when CRT is applied to appropriately selected patients it may be a worthwhile investment not only for our patients but also for our healthcare systems.