SHORT-TERM ANALYSIS OF HEART-RATE-VARIABI LITY FOR RISK STRATIFICATION AFTER MYOCARDIAL-INFARCTION - A METHODOLOGICALLY EFFICIENT ALTERNATIVE TO HOLTER MONITORING

Heart rate variability (HRV) has been established as an important risk parameter in patients surviving myocardial infarction. Recently, anal ysis of HRV - particularly of the standard deviation of NN intervals ( SDNN)-from short term ECG recordings has been proposed as an alternati ve to that from 24 hour Holter monitorings. The present study is the f irst to compare SDNN from short term recordings to that from 24 hour r ecordings with respect to risk stratification after myocardial infarct ion. In 60 patients at the time of discharge from the hospital, SDNN f rom Holter monitoring averaged 93 +/- 30 ms compared to 39 +/- 18 dete rmined from short term recordings. Patients with a prospectively defin ed clinical endpoint differed significantly from those with an unevent ful course with respect to age, left ventricular ejection fraction, me an RR interval from Holter recording (753 +/- 153 vs 921 +/- 132 ms), mean RR from short term recording (783 +/- 153 vs 914 +/- 163 ms), and SDNN from the Holter recording (71 +/- 27 vs 97 +/- 29 ms; p < 0.001) . However, patients with and without a clinical event could not be sep arated by means of SDNN measured from short term ECG registrations (35 +/- 22 vs 41 +/- 19 ms; p = NS). Thus, SDNN measured from short term ECG recordings does not seem to be useful regarding risk stratificatio n of patients after myocardial infarction. Analysis of HRV should be p erformed using 24 hour Holter monitoring, which provides more informat ion and reflects circadian fluctuation in autonomic tone.