Lack of impact of myocardial ischemia on the signal-averaged ECG assessment by time-domain analysis

Michael A.E. Schneider, Christoph A. Nienaber

Research output: Contribution to journalArticlepeer-review


Background: Late potentials represent an arrhythmogenic substrate in chronically infarcted myocardium. It is hypothesized that acute transient ischemia enhances anisotropic electrical ventricular activation and facilitates reentry mechanisms. Study aim was the prospective assessment of the impact of dipyridamole-induced myocardial ischemia on the signal-averaged ECG. Methods: Dipyridamole stress thallium-201 SPECT imaging was utilized to avoid noise contamination of the signal-averaged ECG from exercise and to document evidence and localization of myocardial ischemia or persistent perfusion defects in 68 patients with suspected coronary artery disease. Before and during dipyridamole-induced vasodilatation serial signal-averaged ECG was performed to evaluate the influence of transient ischemia on the occurrence of late potentials. Results: There was a significant difference between heart rate at rest and heart rate under dipyridamole influence in patients with inducible ischemia (70 ± 13 vs. 87 ± 13; P < 0.0001) in contrast to patients without dipyridamole-induced ischemia (74 ± 20 vs. 80 ± 16; n.s.). The number of averaged beats and achieved noise level was comparable between both groups. Thirty-three of 68 patients (49%) revealed dipyridamole-induced ischemia; however, no changes of the SAECG parameters, such as QRS, RMS, LAS at 25-250 and 40-250 Hz bandpass filtering in the leads X, Y, Z and vector magnitude, respectively, were observed as a result of ischemia. Conclusion: These results suggest that transient myocardial ischemia does not affect the signal-averaged ECG. Clinically, the signal-averaged ECG analysis seems not to be helpful in identifying patients with silent ischemia.

Original languageEnglish
Pages (from-to)191-197
Number of pages7
JournalAnnals of Noninvasive Electrocardiology
Issue number3
StatePublished - Jul 2002


  • Dipyridamole
  • Late potential
  • Myocardial ischemia
  • Signal-averaged ECG
  • Thallium-201 SPECT imaging


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