PREDICTIVE VALUE OF WAVELET CORRELATION-FUNCTIONS OF SIGNAL-AVERAGED ELECTROCARDIOGRAM IN PATIENTS AFTER ANTERIOR VERSUS INFERIOR MYOCARDIAL-INFARCTION

Objectives. This study sought to evaluate the prognostic value of wave let correlation functions of the signal averaged electrocardiogram (EC G) for arrhythmic events in patients after myocardial infarction. Back ground. Wavelet transform of the signal-averaged ECG has been shown to be a nonstationary analysis technique describing the time evolution o f frequency spectra throughout the QRS complex, To quantify the wavele t transform, we introduced the new concept of the wavelet correlation function, Methods. The relation among wavelet correlation functions, v entricular late potentials and the site of infarction was investigated in 769 men <66 Sears old who survived the acute phase of myocardial i nfarction (351 [46%] anterior, 418 [54%] inferior infarctions), Signal -averaged ECG recordings were obtained 2 to 3 weeks after infarction, During 6 months of follow-up, 33 patients (4.3%) experienced a maligna nt arrhythmic event, Wavelet correlation functions of the signal-avera ged ECG were evaluated in a time-frequency plane ranging from 25 ms be fore QRS onset to 25 ms after QRS offset in the frequency range betwee n 40 and 100 Hz. Results. Patients with an anterior infarction had low er mean wavelet correlation coefficients (p < 0.001) and a lower incid ence of ventricular late potentials than patients with an inferior inf arction (32.3% vs. 42.7%, p = 0.003). The combination of wavelet corre lation functions and late potentials increased the total predictive ac curacy from 52% to 72% for inferior and from 64%, to 76% for anterior infractions. Conclusions. Spectral changes in the signal-averaged QRS complex are more prominent in anterior than inferior infarctions. Comb ination of late potential analysis and wavelet correlation functions i ncreases the prognostic value for serious arrhythmic events after myoc ardial infarction.