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T peak – T end and T peak – T end /QT Ratio as Markers of Ventricular Arrhythmia Risk in Cardiac Resynchronization Therapy Patients
Author(s) -
BARBHAIYA CHIRAG,
PO JOSE RICARDO F.,
HA SAM,
SCHWEITZER PAUL
Publication year - 2013
Publication title -
pacing and clinical electrophysiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.686
H-Index - 101
eISSN - 1540-8159
pISSN - 0147-8389
DOI - 10.1111/pace.12031
Subject(s) - medicine , cardiology , ventricular tachycardia , cardiac resynchronization therapy , qt interval , repolarization , implantable cardioverter defibrillator , ventricular fibrillation , heart failure , ejection fraction , electrophysiology
Background Cardiac resynchronization therapy (CRT) increases transmural dispersion of repolarization (TDR) and can be pro‐arrhythmic. However, overall arrhythmia risk was not increased in large‐scale CRT clinical trials. Increased TDR as measured by T peak –T end (TpTe) was associated with arrhythmia risk in CRT in a single‐center study. This study investigates whether QT interval, TpTe, and TpTe/QT ratio are associated with ventricular arrhythmias in patients with CRT‐defibrillator (CRT–D). Methods Post‐CRT–D implant electrocardiograms of 128 patients (age 71.3 years ± 10.3) with at least 2 months of follow‐up at our institution's device clinic (mean follow‐up of 28.5 months ± 17) were analyzed for QT interval, TpTe, and TpTe/QT ratio. Incidence of ventricular arrhythmias was determined based on routine and directed device interrogations. Results Appropriate implantable cardioverter‐defibrillator therapy for sustained ventricular tachycardia or ventricular fibrillation was delivered in 18 patients (14%), and nonsustained ventricular tachycardia (NSVT) was detected but did not require therapy in 58 patients (45%). Patients who received appropriate defibrillator therapy had increased TpTe/QT ratio (0.24 ± 0.03 ms vs 0.20 ± 0.04, P = 0.0002) and increased TpTe (105.56 ± 20.36 vs 87.82 ± 22.32 ms, P = 0.002), and patients with NSVT had increased TpTe/QT ratio (0.22 ± 0.04 vs 0.20 ± 0.04, P = 0.016). Increased QT interval was not associated with risk of ventricular arrhythmia. The relative risk for appropriate defibrillator therapy of T p T e /QT ratio ≥ 0.25 was 3.24 (P = 0.016). Conclusion Increased TpTe and increased TpTe/QT ratio are associated with increased incidence of ventricular arrhythmias in CRT–D. The utility of TpTe interval and TpTe/QT ratio as potentially modifiable risk factors for ventricular arrhythmias in CRT requires further study. (PACE 2013; 36:103–108)