Electrocardiographic signal-averaging during atrial pacing and effect of cycle length on the terminal QRS in patients with and without inducible ventricular tachycardia

Mark S. Kremers, William H. Black, Richard Lange, Peter J. Wells, Martha Solo

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16 Scopus citations


Electrocardiographic signal-averaging during sinus rhythm (61 to 99 beats/man) and atrial pacing (100 to 171 beats/min) were performed to determine the effect of heart rate on late potentials in 15 patients without (group 1) and 7 patients with (group 2) inducible sustained ventricular tachycardia (VT). In sinus rhythm (79 ± 12 vs 77 ± 12 beats/min, difference not significant), the duration of the low-amplitude signal <40 μV was longer in group 2 than group 1 (43 ± 21 vs 26 ± 8 ms, p = 0.034) and more patients had late potentials (57 vs 7%, p = 0.021), but QRS duration (121 ± 32 vs 98 ± 19 ms) and terminal voltage (33 ± 33 vs 50 ± 26 ms) were not significantly different. With atrial pacing in group 1 (128 ± 16 beats/ min), 3 patients developed a simultaneous decrease in terminal voltage and an increase in terminal QRS duration consistent with a late potential, but mean total and terminal durations were unchanged. Terminal voltage increased (50 ± 26 to 59 ± 40) but not significantly. With atrial pacing in group 2 (119 ± 12 beats/min) all patients either had a late potential or developed a simultaneous decrease in terminal voltage and an increase in terminal QRS duration (p = 0.001 vs group 1). Root mean square voltage decreased (33 ± 23 to 22 ± 23) and became significantly different from group 1 (p = 0.017). Mean QRS duration, root mean square terminal voltage and low-amplitude terminal QRS duration, however, were unchanged. At rates from 61 to 171 beats/min, the signal-averaged electrocardiogram is largely independent of heart rate, but there is a trend toward a decrease in terminal voltage and an increase in low-amplitude terminal QRS duration in patients with inducible VT. This may be the result of decremental conduction in arrhythmogenic tissue.

Original languageEnglish (US)
Pages (from-to)1095-1098
Number of pages4
JournalThe American journal of cardiology
Issue number15
StatePublished - Nov 1 1990


ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine

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