PREDICTIVE POWER OF INCREASED HEART-RATE VERSUS DEPRESSED LEFT-VENTRICULAR EJECTION FRACTION AND HEART-RATE-VARIABILITY FOR RISK STRATIFICATION AFTER MYOCARDIAL-INFARCTION - RESULTS OF A 2-YEAR FOLLOW-UP-STUDY

Objectives. The aim of this study was to compare the predictive value of mean RR interval assessed from predischarge Holter recordings with that of heart rate variability and left ventricular ejection fraction for risk stratification after myocardial infarction. Background. Heart rate variability is a powerful tool for risk stratification after myo cardial infarction, Although heart rate variability is related to hear t rate, little is known of the prognostic value of 24-h mean heart rat e. Methods, A total of 579 patients surviving the acute phase of myoca rdial infarction were followed up for at least 2 years, Pre discharge heart rate variability, 24 h mean RR interval and left ventricular eje ction fraction were analyzed. Results, During the first 2 gears of fol low-up, there were 54 deaths, 42 of which were cardiac (26 sudden), Sh orter mean RR interval was a better predictor of all-cause mortality a s well as cardiac and sudden death than depressed left ventricular eje ction fraction, Depressed heart rate variability predicted the risk of death better than mean RR interval for sensitivities < 40%. For sensi tivities greater than or equal to 40%, mean RR interval was as powerfu l as heart rate variability, All three variables performed equally wel l in predicting nonsudden cardiac death, For cardiac death prediction, a left ventricular ejection fraction <35% had a 40% sensitivity, 78% specificity and 14% positive predictive accuracy; a mean RR interval < 700 ms had a 45% sensitivity, 85% specificity and 20% positive predict ive accuracy; and a heart rate variability <17 U had a 40% sensitivity , 86% specificity and 20% positive predictive accuracy. Conclusions. P redischarge 24-h mean heart rate is a strong predictor of mortality af ter myocardial infarction that can compete with left ventricular eject ion fraction and heart rate variability.