Abstract 2148: Abnormal T Wave Alternans Could Provide Additional Risk Stratification in Patients with Prolonged QRS Duration
QT dispersion, signal averaged electrocardiogram (SAECG) and T wave alternans (TWA) have been found to be increased susceptibility to life-threatening arrhythmias or cardiac death
(LTA/CD). Patients with heart diseases often present prolonged QRS duration (p-QRSd), however the risk stratification in patients with p-QRSd still remains. We investigated whether QT dispersion, SAECG and TWA would provide additional risk stratification in patients with p-QRSd. We studied 52 patients (47 males, mean age 66±9 yrs) with QRS duration ≥ 120ms (34 RBBB type and 18 LBBB type) who had heart diseases (45 coronary artery disease and 7 dilated cardiomyopaty). QT dispersion was measured from standard 12-lead ECG. The filtered QRS duration (f-QRS) and root mean square voltage of the terminal 40ms of the QRS complex (RMS40) were obtained by SAECG. TWA was measured with the CH 2000. TWA was considered positive when the alternans with alternans voltage ≥ 1.9μV and alternance ratio ≥ 3 was sustained ≥ 1 minute in vector magnitude, X, Y, Z, V4 or two precordal leads at heart rate ≤ 110bpm. TWA was classified negative when the alternans wasn’t presented at heart rate ≤ 110bpm and considered indeterminate if the record didn’t meet either positively or negatively. Abnormal TWA was defined as positive or indeterminate. An abnormal TWA test was present in 56% (23 patients had negative TWA, 11 had indeterminate and 18 had positive). During the follow-up periods (69±41 months), 15 patients had life-threatening arrhythmias (n=12) and/or cardiac death (n=7). Univariate analysis revealed left ventricular ejection fraction (LVEF), RMS40 and abnormal TWA (n=29) as significant variables, however there was no significant difference in LTA/CD rate between BBB types, and no associations between QT dispersion and LTA/CD. On logistic regression analysis, only LVEF (p=0.02) and abnormal TWA (p=0.02, odds ratio 9.803 [95%CI 1.430 to 67.207]) were independently associated with LTA/CD. Abnormal T wave alternans could provide additional risk stratification in patients with prolonged QRS duration.