High Frequency QRS Analysis From Orthogonal Leads

We analysed high frequency averaged QRS (HFQRS) in orthogonal leads and different passbands. Three groups of subjects were compared: healthy subjects, ischemic heart disease (IHD) and dilated cardiomyopathy (DCM) patients. Among the IHD group, those with heart failure (HF) symptoms were identified. Investigated parameters included HFQRS maximal amplitude, HFQRS power, and HFQRS fragmentation based on normalized length of the HFQRS line. The study aimed at assessing (1) group differences in relation to the passband, lead, and parameter, and (2) the reproducibility of parameters. Results: Significant differences were found between healthy subjects and IHD or DCM in all parameters and passbands. Some singularities of significance existed between IHD and DCM. Significant differences were also found between IHD sub-groups with and without HF symptoms, and these existed over more frequency bands. Conclusion: HFQRS parameters are frequency dependent and this dependency should be tested to eliminate singularities in statistical significances. Differences between groups with or without HF symptoms were found mainly at higher passbands, regardless of deterioration of reproducibility. Lead X appeared to be the lead with maximal differences between groups.