Cardiac contractility modulation: an effective treatment strategy for heart failure beyond reduced left ventricular ejection fraction?

ABSTRACT

Heart failure (HF) with preserved ejection fraction (HFpEF) causes a progressive limitation of functional capacity, poor quality of life (QoL) and increased mortality, yet unlike HF with reduced ejection fraction (HFrEF) there are no effective device-based therapies. Both HFrEF and HFpEF are associated with dysregulations in myocardial cellular calcium homeostasis and modifications in calcium-handling proteins, leading to abnormal myocardial contractility and pathological remodelling. Cardiac contractility modulation (CCM) therapy, based on a pacemaker-like implanted device, applies extracellular electrical stimulation to myocytes during the absolute refractory period of the action potential, which leads to an increase in cytosolic peak calcium concentrations and thereby the force of isometric contraction promoting positive inotropism. Subgroup analysis of CCM trials in HFrEF has demonstrated particular benefits in patients with LVEF between 35% and 45%, suggesting its potential effectiveness also in patients with higher LVEF values. Available evidence on CCM in HFpEF is still preliminary, but improvements in terms of symptoms and QoL have been observed. Future large, dedicated, prospective studies are needed to evaluate the safety and efficacy of this therapy in patients with HFpEF.