Electrocardiographic predictors of bradycardia-induced torsades de pointes in patients with acquired atrioventricular block

• Published in: Heart rhythm Vol. 12; no. 3; pp. 498 - 505
• Main Authors: Cho, Min Soo, Nam, Gi-Byoung, Kim, Yong-Guin, Hwang, Ki-Won, Kim, Yoo Ri, Choi, HyungOh, Kim, Sung-Hwan, Rhee, Kyoung-Suk, Kim, Nam-Joon, Kim, June Soo, Kim, Jun, Choi, Kee-Joon, Kim, You-Ho
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.03.2015
• Subjects: Aged; Aged, 80 and over; Algorithms; Atrioventricular block; Atrioventricular Block - complications; Atrioventricular Block - physiopathology; Bradycardia; Cardiovascular; Case-Control Studies; Electrocardiography - methods; Female; Humans; Long QT syndrome; Long QT Syndrome - complications; Long QT Syndrome - physiopathology; Male; Middle Aged; Predictive Value of Tests; Risk Factors; Sensitivity and Specificity; T waves; Torsades de pointes; Torsades de Pointes - diagnosis; Torsades de Pointes - etiology; Torsades de Pointes - physiopathology; TdP; CI; LQTS; ROC; ECG; Tpe; IQR; AVB; AUC; T waves; Bradycardia; Torsades de pointes; Long QT syndrome; Atrioventricular block; TWA; torsades de pointes; T peak to end interval; long QT syndrome; T-wave alternans; area under the curve; interquartile range; electrocardiography; atrioventricular block; confidence interval; receiver operating characteristic
• ISSN: 1547-5271; 1556-3871; 1556-3871
• DOI: 10.1016/j.hrthm.2014.11.018

Predictors of torsades de pointes (TdP) in bradyarrhythmia-induced acquired long QT syndrome are not well defined. The purpose of this study was to search for electrocardiographic (ECG) TdP predictors in patients with acquired atrioventricular block (AVB) and QT prolongation. 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. 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%). An algorithm combining specific T-wave morphologies was useful for identifying patients with AVB who are at risk for developing TdP.