Approaches to experimental arrhythmias in heart failure

Sudden cardiac death accounts for at least 50% of the mortality of patients with heart failure. Available clinical evidence suggests that lethal ventricular arrhythmias are responsible for the vast majority of cases of sudden death in heart failure. However, despite extensive clinical investigation over the last decade, there has been relatively little experimental study of the mechanisms underlying the development of lethal ventricular arrhythmias in heart failure. In addition to the original process leading to myocardium alterations, the role of other arrhythmogenic mechanisms such as ventricular overload and neuro endocrine activation remains to be elucidated. In ventricular hypertrophy both reentry and triggered activity may induce arrhythmias. Some studies on experimental models of heart failure did not provide consistent results concerning electrophysiological modifications and their relations with arrhythmias. Few studies in man in vivo are in favor of prolongation as well as increased dispersion of repolarisation in patients undergoing heart transplantation for idiopathic dilated cardio-myopathy. Further studies will need to be undertaken to clarify mechanisms underlying arrhythmias in heart failure.