[Prognostic value of study of heart rate variability in chronic cardiac insufficiency].

Analysis of heart rate variability is an attractive, non-invasive method for studying the cardiac response to stimulation by the autonomic nervous system which is decreased in chronic cardiac failure. The prognostic value of heart rate variability in cardiac failure has been the subject of recent research. The 24-hour standard deviation is the commonest parameter with an independent predictive value for mortality. However, its threshold value is variable according to the different studies. The percentage of successive RR intervals varying by more than 50 ms is a sign of parasympathetic activity and is not found to be an independent prognostic factor by all workers. The results of values of low frequency on spectral analysis are contradictory. Finally, the Poincaré graphic method showing an abnormal graph is one of the only predictive factors of sudden death. Blood pressure variability will probably complete the analysis of heart rate variability as a prognostic factor of chronic heart failure.