The role of heart rate variability in risk stratification for adverse postoperative cardiac events.

There is growing evidence of a strong association between the compromised autonomic nervous system and sudden cardiac death. Heart rate variability (HRV) measures are widely used to measure alterations in the autonomic nervous system. Several studies with cardiac patients show that decreased HRV as well as baroreceptor dysfunction are more powerful predictors for sudden cardiac death than established clinical predictors such as left ventricular ejection fraction. One-third of all postoperative complications and more than half of the deaths are due to cardiac complications. Several risk indices are useful for immediate perioperative short-term, but not for long-term outcome risk stratification of an individual patient. Currently, there are no clinically assimilated methods for long-term postoperative risk assessment. Recently, few studies have shown that preoperatively decreased HRV can independently predict postoperative long-term mortality. Further studies with surgical patients are needed to establish a possible predictive value of preoperative baroreceptor dysfunction, alone and combined with HRV, for short- and long-term postoperative outcome.