[Arrhythmia risk stratification in patients with heart failure: prognostic evaluation of arrhythmia risk]

Sudden cardiac death is one of the more frequent causes of death in patients with heart failure. Thus, identification of patients at risk is a major clinical problem not only for the unpredictability of the event but also for the continuous growth of patients' number. The most widely used parameter for risk stratification is ejection fraction. Unfortunately, its predictive accuracy is limited and often it is impossible to distinguish patients with an increased arrhythmic mortality from those with an increased mortality due to pump failure. Heart rate variability and baroreflex sensitivity analysis has been largely utilized to obtain information on autonomic modulation of sinus node as well as to identify patients at risk. However, at variance with results observed in post-myocardial infarction patients, lower values of both parameters have been reported in patients with either an increased total or arrhythmic mortality. More recently, T wave alternans analysis has been found effective in identifying patients with an increased arrhythmic risk. Ongoing studies will provide evidence to support the use of this non-invasive technique in patients with cardiac insufficiency. Finally, the role of programmed electrical stimulation in heart failure patients appears limited. Inducibility of monomorphic sustained ventricular tachycardia seems to correlate better with the presenting clinical arrhythmia than with patient outcome. In conclusion, our capability of identifying heart failure patients at risk for arrhythmic death is far from being satisfactory. It is possible that the combination of results of multiple non-invasive tests such as reduction in ejection fraction and positivity for T wave alternans may not only provide general prognostic information but also facilitate the appropriate identification of patients at risk who may benefit from antiarrhythmic therapy.