[Arrhythmia risk stratification based on etiological and anatomo-structural factors].
In patients with heart failure, sudden death is very common, particularly in subjects in NYHA functional class II and III (respectively 50-80% and 30-50% of all deaths). The mechanisms at the root of sudden death depend on whether heart failure is secondary to an ischemic or non-ischemic heart disease. In ischemic heart disease, sudden death is mainly arrhythmic (ventricular tachycardia/ventricular fibrillation caused by the reentry circuits in the infarct area or by acute ischemic episodes or bradyarrhythmia). In non-ischemic heart disease, the percentage of arrhythmic sudden deaths seems to be lower. Furthermore, a percentage of sudden death cases with heart failure can be linked to electromechanical dissociation and to pulmonary or systemic embolism. Moreover the risk stratification level differs depending on whether heart failure is caused by an ischemic or a non-ischemic heart disease. The various non-invasive studies mainly employed in patients with ischemic heart disease cannot be reliably used to study patients with non-ischemic heart disease. Even the programmed ventricular stimulation demonstrated prognostic reliability only in cases involving ischemic heart disease. The therapeutic approach may also be conditioned by the heart disease responsible for heart failure. To date, for example, all the studies published on primary prevention of sudden death with an implantable defibrillator have been carried out in patients with ischemic heart disease.