[Improving left ventricular contractility by stimulation during the absolute refractory period--cardiac contractility modulation (CCM)].

Cardiac contractility modulation (CCM) is a treatment option for patients with systolic ventricular dysfunction, independent of QRS duration, moderate to severe systolic heart failure and symptoms despite optimal medical therapy. In contrast to cardiac resynchronization therapy (CRT) which has been an established therapy in patients with wide QRS and ventricular asynchrony, CCM can enhance cardiac contractility in patients independent of QRS duration. Whereas inotropic drugs increase oxygen demand, CCM works without additional myocardial oxygen need and without reference to asynchrony. Non-excitatory signals applied during the absolute refractory period have been shown to enhance the strength of left ventricular contraction in animals and humans with heart failure probably due to normalization of myocardial gene expression. Several multicenter studies have demonstrated safety and efficacy of CCM in patients with medically refractory heart failure. We describe the specific technical aspects and conditions in clinical application of CCM.