Butterworth bi-directional and BiSpec™ filters in the assessment of ventricular late potentials:: A comparative study

The Ventricular Late Potentials (VLP) are low amplitude signals originated from electrically unstable regions of damaged myocardium. Due to low amplitude, VLP are defected on the body surface by statistical techniques and band-pass filtering to reduce the baseline noise and exclude high-energy components BiSpec(TM) filter is currently in use as an alternative for VLP analysis, but no clinical study validating ifs application has been performed so far. To accomplish this task if was conducted a clinical study to compare BiSpec 40 Hz filter (BS) and four pole 40-250 Hz band-pass Butterworth bidirectional filter (BD) regarding their diagnostic properties. If was studied retrospectively 170 patients without bundle branch block, with signal-averaged EGG, using Predictor SAECG System (ART, Texas) and divided into three group The variables analyzed were DUR, RMST, RMS40 and LAS40. It was found significant differences between BS and ED for RMST in all groups (p much less than0.001), DUR in GI (p<0.05) and LAS40 in GII (p<0.05). The distribution of diagnostic results were significantly different in GII and GIII (p<0.05) and linear correlation were <0.7 in GI and GII Sensitivity was lower for BS than ED (p<0.05). This study demonstrates that BS and ED provide significantly different diagnostic results and suggests that normality intervals should be reevaluated for BS.