Prognostic value of analysis of heart rate variability in chronic heart failure.

Analysis of heart rate variability is an attractive, non-invasive method fo r studying the cardiac response to stimulation by the autonomic nervous sys tem 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 commo nest 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 SO ms is a s ign of parasympathetic activity and is not found to be an independent progn ostic factor by all workers. The results of values of low frequency on spectral analysis are contradicto ry. Finally, the Poincare graphic method showing an abnormal graph is one of th e only predictive factors of sudden death. Blood pressure variability will probably complete the analysis of heart rat e variability as a prognostic factor of chronic heart failure.