July 17, 2007Open Access
View Full PaperRepolarization variability in the risk stratification of MADIT II patients
Key Result
Elevated T-wave variability (>59 microV) was predictive of ventricular tachyarrhythmias requiring appropriate ICD therapy (HR 2.0; 95% CI 1.2-3.5; P=0.01).
Study Design
Type
Cohort (n=275)
Multicenter
Yes
Structured PICO
Does elevated T-wave variability predict ventricular tachyarrhythmias requiring appropriate ICD therapy in MADIT II patients?
P
Population
275 ICD patients from the MADIT II trial, excluding those with intraventricular conduction abnormalities or atrial fibrillation, followed for 2 years.
E
Exposure
High T-wave variability (TWV >59 microV) measured from ambulatory Holter recordings
C
Comparator
Low T-wave variability (TWV ≤59 microV)
O
Outcome
Ventricular tachyarrhythmias requiring appropriate ICD therapy (ventricular tachycardia or fibrillation)hard clinical
Holter-derived T-wave variability is a significant predictor of ventricular tachyarrhythmias requiring ICD therapy in patients with ischemic cardiomyopathy.
Main Result
Hazard Ratio: 2 (95% CI 1.2–3.5)
p-value: p=0.01
Abstract
AIMS: QT variability has been reported to be associated with ventricular arrhythmias and sudden cardiac death. There is limited data regarding variability in T-wave morphology and its prognostic value. In this study, we present a novel approach for the measurement of T-wave variability (TWV) reflecting changes in T-wave morphology, and we investigate the prognostic significance of Holter-derived TWV in patients with and without ventricular arrhythmias requiring appropriate implantable cardioverter defibrillator (ICD) therapy from the Multicenter Automatic Defibrillator Implantation Trial II (MADIT II). Methods Study population consisted of 275 ICD patients from MADIT II after excluding patients with intraventricular conduction abnormalities or atrial fibrillation. TWV was measured based on amplitude variance of T-wave amplitude. Results During 2-year follow-up, 58 (21%) patients had appropriate ICD therapy for ventricular tachycardia or fibrillation. Patients with appropriate ICD therapy had higher levels of TWV measures than those without arrhythmic events. After adjustment for heart rate, ejection fraction, and significant clinical predictors of arrhythmic events, a Cox proportional-hazards regression model revealed that dichotomized TWV values were predictive for ventricular tachyarrhythmias requiring appropriate ICD therapy (hazard ratio, 2.0; 95% CI; 1.2-3.5; P=0.01). On the basis of the comprehensive testing, TWV value >59 microV was found predictive for arrhythmic events in MADIT II population. CONCLUSION: Our newly designed method for the assessment of repolarization variability in ambulatory Holter recordings detected transient variability of T-wave morphology, which was predictive for ventricular tachyarrhythmias in the MADIT II population.