GLIDING WINDOW FAST FOURIER-TRANSFORM ANALYSIS - A NEW METHOD FOR DISCOVERING THE CONTRIBUTION OF HIGHER FREQUENCIES IN SIGNAL-AVERAGED ECG

OBJECTIVE: An attempt to detect the 'parasitic contribution' of high f requencies in the electrocardiogram signal. DESIGN: A new method - gli ding window fast Fourier transform analysis (GWFFTA) - was developed. It was applied in healthy subjects and in patients with acute myocardi al infarction. SETTING: Faculty of Medicine and University Hospital. P ATIENTS: The GWFFTA was used in 29 healthy volunteers and in a group o f 30 patients with myocardial infarction, on day 7 to 14 after admissi on to a coronary unit. INTERVENTION: Noninvasive examination, performe d under standard conditions. MAIN RESULTS: GWFFTA provides better repr oducible results compared with 'classic' fast Fourier transform analys is. The parasitic contribution of high frequencies within QRS complex and ST segment in patients with acute myocardial infarction is indepen dent of presence or absence of late potentials. Contribution of high f requencies are three times higher in patients with acute myocardial in farction than in healthy probands. CONCLUSIONS: GWFFTA is a reproducib le method of detection of high frequencies during whole heart activati on. Contribution of high frequencies in patients with acute myocardial infarction reflects the state of the entire myocardium. It is also co nfirmed by the lack of correlation with the presence or absence of lat e potentials. Late potentials are more reflective of focal changes.