Min Soo Cho1, Gi-Byoung Nam2, Yong-Guin Kim1, Ki-Won Hwang1, Yoo Ri Kim1, HyungOh Choi1, Sung-Hwan Kim1, Kyoung-Suk Rhee3, Nam-Joon Kim4, June Soo Kim4, Jun Kim1, Kee-Joon Choi1, You-Ho Kim1. 1. Heart Institute, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea. 2. Heart Institute, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea. Electronic address: gbnam@amc.seoul.kr. 3. Division of Cardiology, Department of Internal Medicine, Chonbuk National University Hospital, Chonbuk National University, Chonju, Korea. 4. Department of Cardiology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
Abstract
BACKGROUND: Predictors of torsades de pointes (TdP) in bradyarrhythmia-induced acquired long QT syndrome are not well defined. OBJECTIVE: The purpose of this study was to search for electrocardiographic (ECG) TdP predictors in patients with acquired atrioventricular block (AVB) and QT prolongation. METHODS: We analyzed 12-lead ECGs from 20 patients (15 females, age 65.9 ± 15.6 years) with TdP episodes from among 898 AVB patients (2.2%) in 3 tertiary hospitals. The ECG repolarization parameters in TdP patients were compared with those of 80 age- and sex-matched control AVB patients with no TdP episodes. RESULTS: TdP was initiated by premature ventricular complexes with a long-short sequence of activation. The average cycle length of the long sequence was 1289.9 ± 228.9 ms and was 2.3 ± 0.6 times longer than the cycle length of the short sequence. TdP patients had a significantly longer mean QT interval (716.4 ± 98.9 ms vs 523.2 ± 91.3 ms, P = .001), mean T peak to end interval (334.2 ± 59.1 ms vs 144.0 ± 73.7 ms, P = .001) and a higher T peak to end interval/QT ratio (0.49 ± 0.09 vs 0.27 ± 0.11, P = .001) compared with non-TdP controls. TdP patients showed a higher prevalence of notched T waves in which T2 was at least 3 mm taller than T1 (45.0% vs 1.3%, P = .001), triphasic T waves (30.0% vs 1.3%, P = .001), reversed asymmetry (20.0% vs 0%, P = .001), and T-wave alternans (35.0% vs 0%, P = .001). An algorithm combining these morphologic parameters was able to differentiate TdP patients from non-TdP patients with high sensitivity (85.0%) and specificity (97.5%). CONCLUSION: An algorithm combining specific T-wave morphologies was useful for identifying patients with AVB who are at risk for developing TdP.
BACKGROUND: Predictors of torsades de pointes (TdP) in bradyarrhythmia-induced acquired long QT syndrome are not well defined. OBJECTIVE: The purpose of this study was to search for electrocardiographic (ECG) TdP predictors in patients with acquired atrioventricular block (AVB) and QT prolongation. METHODS: We analyzed 12-lead ECGs from 20 patients (15 females, age 65.9 ± 15.6 years) with TdP episodes from among 898 AVB patients (2.2%) in 3 tertiary hospitals. The ECG repolarization parameters in TdP patients were compared with those of 80 age- and sex-matched control AVB patients with no TdP episodes. RESULTS: TdP was initiated by premature ventricular complexes with a long-short sequence of activation. The average cycle length of the long sequence was 1289.9 ± 228.9 ms and was 2.3 ± 0.6 times longer than the cycle length of the short sequence. TdP patients had a significantly longer mean QT interval (716.4 ± 98.9 ms vs 523.2 ± 91.3 ms, P = .001), mean T peak to end interval (334.2 ± 59.1 ms vs 144.0 ± 73.7 ms, P = .001) and a higher T peak to end interval/QT ratio (0.49 ± 0.09 vs 0.27 ± 0.11, P = .001) compared with non-TdP controls. TdP patients showed a higher prevalence of notched T waves in which T2 was at least 3 mm taller than T1 (45.0% vs 1.3%, P = .001), triphasic T waves (30.0% vs 1.3%, P = .001), reversed asymmetry (20.0% vs 0%, P = .001), and T-wave alternans (35.0% vs 0%, P = .001). An algorithm combining these morphologic parameters was able to differentiate TdP patients from non-TdP patients with high sensitivity (85.0%) and specificity (97.5%). CONCLUSION: An algorithm combining specific T-wave morphologies was useful for identifying patients with AVB who are at risk for developing TdP.