Reproducibility of the spectral turbulence analysis of the signal‐averaged electrocardiogram

Spectral turbulence analysis (STA) of the signal-averaged electrocardiogram (SAECG) is a recently proposed technique to identify patients with ventricular tachycardia as well as patients at risk for arrhythmic events after acute myocardial infarction (MI). The short-term reproducibility of this technique has been previously reported; our study evaluates the reproducibility of STA by shifting the reference points. Twenty patients with acute MI were recruited. SAECG was recorded 13 days after onset of the acute MI. Unfiltered data were transferred and analyzed by personal computer software for spectral turbulence analysis according to the standard condition; reference points of the segment of interest were shifted from QRS offset -10 ms and QRS onset -10 ms to QRS offset +10 ms and QRS onset +10 ms, step 2 ms. Thus, 10 analyses were computed. Reproducibility of the results was calculated using the coefficient of variation (CV) and the relative error (RE). The reproducibility of the classification (RC) was defined as the percentage of the identical classification compared with the standard segment. CV of the intersegment correlation standard deviation was statistically higher than the other parameters regardless of the lead considered. RE was not different in each parameter and in each lead. RC was > 90% in all parameters, except in spectral entropy which showed an RC > 80%. Reproducibility of the STA introducing a temporal shift in the analyzed segments was high in all considered parameters.