[Sudden cardiac death, a major scientific challenge]

Sudden death is responsible for 350,000 deaths each year in Europe, or 1000 deaths each day, equivalent to the combined mortality from the most lethal cancers (breast, lung and colorectal). Unfortunately, sudden death is widely considered to be "natural", being due to unknown but critical cardiac disorders leading to sudden arrest of cardiac activity. Awareness of its potential preventability is inadequate. Indeed, 80% of cases of sudden death are associated with extremely rapid heartbeats, an "electric tornado" called ventricular fibrillation, caused by ultrarapid firing of ectopic foci or chaotic wave propagation. This arrhythmia strikes like lightning Although it can be associated with myocardial infarction, most victims have structurally normal or slightly altered hearts. The cells which cause this ultrarapid firing originate from the Purkinje system, which constitutes just a fraction (2%) of total cardiac mass. This is borne out by the fact that the risk of fatal arrhythmic events can be reduced by focal thermoablation. What is most important is to identify subjects at risk of such events. It has been suggested that there exists an unidentified subclinical electrical disharmony, which converts into a tornado of ultimately fatal clinical events at a certain threshold level. High-resolution bioelectrical cardiac mapping, functional imaging, and treatment of electrical field disorders are major scientific challenges given their complexity, intraindividual dynamics and interindividual variability.