The Effects of 40 Hz Low-Pass Filtering on the Magnitude of the Spatial Ventricular Gradient

The magnitude of the spatial ventricular gradient (MSVG) is an attractive parameter in electrocardiogram (ECG) monitoring applications.The MSVG is most commonly obtained from 150 Hz low-pass filtered resting ECGs. However, monitoring applications typically utilize 40 Hz low-pass filtered ECG data. The extend to which the value of the MSVG is affected by the utilization of 40 Hz low-pass monitoring ECG filters over the commonly used 150 Hz low-pass resting ECG filters has not previously been reported.The aim of this research was to quantify the differences between MSVG values computed using 40 Hz low-pass filtered ECG data (MSVG40) and 150 Hz low-pass filtered ECG data (MSVG150). The differences between the MSVG40 and the MSVG150 were quantified as systematic error (mean difference) and random error (span of Bland-Altman 95% limits of agreement) using a study population of 726 subjects. The systematic error was found to be 0.013 mV ms [95% confidence interval: 0.008 mV ms to 0.018 mV ms]. The random error was quantified as 0.282 mV ms [95% confidence interval: 0.266 mV ms to 0.298 mV ms].Our findings suggest that it is possible to record accurate MSVG values using 40 Hz low-pass filtered ECG data.