Seeing is believing: acute haemodynamic response to predict long-term outcome in cardiac resynchronization therapy.

Many heart failure specialists still believe that the pathophysiology of cardiac resynchronization therapy (CRT) is incompletely understood; however, it must be emphasized that the main effects of biventricular pacing have already been described more than a decade ago. In 1994, Cazeau et al. reported how biventricular pacing improves clinical signs and symptoms of heart failure, acutely increases cardiac output and decreases pulmonary capillary wedge pressure and that those effects were likely mediated by better synchronization of left ventricular (LV) mechanical contraction. However, despite the obvious clinical success of this novel therapeutic approach, the authors were very modest with speculations on the impact on mortality: