[Brief analysis of heart rate variability in for determining prognosis in the post-myocardial infarct period: methodologically reliable alternative to long-term ECG?].

Heart rate variability (HRV) has been established as an important risk parameter in patients surviving myocardial infarction. Recently, analysis of HRV-particularly of the standard deviation of NN intervals (SDNN)--from short term ECG recordings has been proposed as an alternative to that from 24 hour Holter monitorings. The present study is the first to compare SDNN from short term recordings to that from 24 hour recordings with respect to risk stratification after myocardial infarction. In 60 patients at the time of discharge from the hospital, SDNN from Holter monitoring averaged 93 +/- 30 ms compared to 39 +/- 18 determined from short term recordings. Patients with a prospectively defined clinical endpoint differed significantly from those with an uneventful course with respect to age, left ventricular ejection fraction, mean 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 Hotler recording (71 +/- 27 vs 97 +/- 29 ms; p < 0.001). However, patients with and without a clinical event could not be separated 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 stratification of patients after myocardial infarction. Analysis of HRV should be performed using 24 hour Holter monitoring, which provides more information and reflects circadian fluctuation in autonomic tone.