Debate on Cardiac Resynchronisation Therapy

Intraventricular delay, especially left bundle branch block (LBBB), is present in up to 20% of patients with heart failure due to left ventricular (LV) dysfunction and can be considered a marker of disease. Although LBBB has been always considered a consequence rather than a cause of LV impairment, the delayed movement of the lateral wall towards the interventricular septum leads to a waste of energy and a reduced efficacy of LV contraction.