Absence of heart rate variability predicts mortality in HF

Among patients with heart failure (HF), the absence of heart rate variability, defined as a standard deviation of RR intervals (SDNN) less than 50 msec was associated with a 51.4 percent annual mortality compared to 5.5 percent in those who had an SDNN greater than 100 msec and 12.7 percent in those who had an SDNN of 50 to 100 msec (p<0.0001).