Ventricular arrhythmias are a major cause of sudden cardiac death in Europe (350,000 deaths / year). The majority of these deaths cannot be anticipated and prevented due to the low sensitivity of current risk criteria. Cardiac mapping of surviving patients has shown the presence of distinctive electrical signals in areas generating arrhythmias. These signals are currently recorded by invasive measurement (catheters) as they are not perceived by electrocardiography or electrical mapping on the surface of the thorax. Detection of the magnetic components of these signals would allow a vector measurement including currents electrically invisible consequence of an altered myocardial zone. The aim of the MAESTRO project is to implement a network of ultrasensitive magnetometers on models of pathological hearts (ex-vivo and in-vivo) in order to develop a non-invasive method of identifying signals associated with a high risk of sudden cardiac death.