RISK STRATIFICATION AFTER MYOCARDIAL-INFA RCTION - VALUE OF HEART-RATE, ITS VARIABILITY, AND LEFT-VENTRICULAR EJECTION FRACTION

Heart rate variability is a useful parameter for risk stratification a fter myocardial infarction. However, the relationship between heart ra te itself and its variability has not been adequately studied. The aut hors compared the average RR interval of 24 hours recorded by Holter m onitoring with the variability of heart rate and of left ventricular e jection fraction to assess the risk of death after myocardial infarcti on. A total of 579 patients was followed up for 2 years after acute my ocardial infarction. During this period, there were 54 deaths, 42 of c ardiac origin, 26 being classified as sudden death. The positive predi ctive value of left ventricular ejection fraction was lower than those of mean RR interval and the variability of heart rate for overall mor tality, cardiac mortality and sudden death. The three indices were ess entially equivalent for the prediction of non-sudden cardiac death. Th e positive predictive value of heart rate variability was better than the mean RR interval for sensitivities < 40%, for all cause mortality. However, for sensitivities > 40%, the two parameters were equivalent or slightly in favour of the mean heart rate over 24 hours. The author s conclude that the mean RR interval over 24 hours is an important pro gnostic index after myocardial infarction. This index is more powerful than left ventricular ejection fraction and comparable to heart rate variability.