Failure of signal-averaged electrocardiography with use of time-domain variables to predict inducible ventricular tachycardia in patients with conduction defects.
OBJECTIVE
To extend the application of signal-averaged electrocardiography (SAECG) to patients with ventricular conduction defects by analysis of electrocardiographic (ECG) time-domain variables.


METHODS
In 123 consecutive patients with a QRS duration of 118 ms or more on a resting ECG and without evidence of an accessory pathway, SAECG was done at the time of electrophysiologic (EP) study. For EP testing, up to three stimuli were delivered during two paced drives from two right ventricular sites. A "positive" EP result was defined as monomorphic ventricular tachycardia that lasted for more than 30 seconds or necessitated intervention. Data were obtained for four time-domain variables. All variables were analyzed for differences between patients with EP-positive and those with EP-negative results.


RESULTS
Unfiltered QRS duration was the only time-domain ECG variable that was statistically different (P = 0.02) between patients with EP-positive and those with EP-negative results (141.3 and 147.8 ms, respectively); this difference persisted when patients with right bundle branch block were excluded from analysis. This finding is the opposite of previously reported observations. When only patients with ischemic heart disease were analyzed, no SAECG variables were significantly different between patients with inducible ventricular tachycardia and those without it.


CONCLUSIONS
High-resolution ECG time-domain variables cannot be used to predict inducibility of ventricular tachycardia during EP testing in patients with conduction defects.
Division of Cardiovascular Diseases and Internal Medicine, Mayo Clinic Rochester, MN 55905.
S R
SR
Ommen
S C
SC
Hammill
K R
KR
Bailey
D002037:Bundle-Branch Block / Q000150:complications / Q000503:physiopathology; D002304:Cardiac Pacing, Artificial; D004562:Electrocardiography; D004594:Electrophysiology; D005260:Female; D005544:Forecasting; D006327:Heart Block / Q000150:complications / Q000503:physiopathology*; D006801:Humans; D008297:Male; D011446:Prospective Studies; D012815:Signal Processing, Computer-Assisted; D017180:Tachycardia, Ventricular / Q000209:etiology / Q000503:physiopathology*