T Wave Alternans in high arrhythmic risk patients: Analysis in time and frequency domains: A pilot study

Background T wave alternans (TA) is a repolarisation phenomenon manifesting as a microvolt beat to beat change in the amplitude of the T wave and ST segment. TA has been shown to be a predictor of arrhythmic risk in unselected myocardial infarction populations. TA has not been used to differentiate risk within the ischaemic cardiomyopathy population. Methods The subjects investigated comprised, Group 1: 7 stable patients with remote (>20 months) extensive myocardial scarring and no arrhythmic events (NYHA 3 and 4). Group2: 9 post infarction patients with malignant arrhythmia and implantable defibrillator. During breath holding, 20 continuous QRST complexes from each patients X, Y and Z leads were digitally recorded. Time domain, resultant absolute difference vectors (ATA), were calculated for alternate resultant T wave sequences. Group differences between the magnitude and temporal distribution of mean ATAs and their spectral and cross-spectral analysis were compared. Results Group 1 v Group 2 mean ATAs were 10.7 (7.17) v 11.7 (8.48) respectively, not significant. Each group had a homogenous temporal distribution of ATAs. Both group's largest mean ATA frequency components were between 0 to 25 Hz, the largest ATA component being at the DC frequency. Cross spectral analysis showed no significant differences in group ATA frequency content. Conclusion The frequency content and microvolt magnitude of T wave alternans was not significantly different in these two groups. The specificity of T wave alternans for differentiating arrhythmic risk in post infarction scarring and heart failure needs investigation.

                                            [
  "009:25"
]
                                        

                                            {
  "fn": "NIH",
  "@type": "vcard:Contact",
  "hasEmail": "mailto:info@nih.gov"
}
                                        

                                            [
  {
    "@type": "dcat:Distribution",
    "title": "Official Government Data Source",
    "mediaType": "text/html",
    "description": "Visit the original government dataset for complete information, documentation, and data access.",
    "downloadURL": "https://www.ncbi.nlm.nih.gov/pmc/articles/PMC101381/"
  }
]
                                        

                                            [
  "arrhythmic-risk",
  "electrophysiology",
  "myocardial-infarction",
  "nih",
  "t-wave-alternans"
]
                                        

                                            [
  "009:032"
]
                                        

                                            {
  "name": "National Institutes of Health",
  "@type": "org:Organization"
}
                                        

                                            [
  "NIH"
]