Click on image to view larger version.

Figure 1 Decrease in heart rate variability (HRV) before ischemic events. Top: A significant decrease in high frequency (hf) (p = 0.04) occurred in the period from 60 min to 10 min before the ischemic event, followed by a further depression during the 4 min preceding the event. Low frequency (lf) HRV decreased significantly at 4 min before the ischemic event but not at earlier time points. Lower: Changes in heart rate (HR) in the hour surrounding ischemic events. *p < 0.05; **p < 0.01, unadjusted p levels comparing target and preceding HRV or HR level.