HEART-RATE-VARIABILITY USED AS AN ARRHYTHMIA RISK STRATIFIER AFTER MYOCARDIAL-INFARCTION

Heart rate variability (HRV) is considered to represent a noninvasive tool to assess cardiac autonomic tone at the level of the sinus node, It has been shown to have predictive power for risk assessment in pati ents surviving acute myocardial infarction. For this purpose, HRV shou ld be assessed from 24-hour Holter recordings obtained 7-10 days follo wing the infarction. Although there is some recovery of HRV during the first 3 months after infarction, HRV remains reduced in postinfarctio n patients compared to values obtained in healthy individuals. Compare d to assessment of left ventricular function as a risk marker, HRV is superior with respect to prediction of arrhythmic events and sudden de ath whereas both parameters yield comparative power for prediction of total cardiac mortality. Since the predictive power of HRV analysis al one is relatively low, the combined use of HRV measurements together w ith traditional risk markers (such as ventricular ectopic beats, signa l-averaged EGG, or left ventricular function) results in improved risk prediction with positive predictive accuracy in the range of 30%-50%.