Abstract 18610: Among Several Surface ECG Measurements and Clinical Indicators, Only Tpeak-Tend and Cornell Voltage Predict Appropriate ICD Therapy In Patients with Ischemic Cardiomyopathy
Introduction: Though CAD and depressed LVEF confer high risk for sudden cardiac death due to ventricular tachyarrhythmia, further risk stratification within this population is needed. Surface ECG markers of dispersion of ventricular repolarization, including Tpeak-Tend (Tpe), QTc, and Q-Tpeak, have been suggested as predictors of risk for ventricular arrhythmia. We assessed which of these variables is most powerful for prediction of clinical arrhythmic events in this population, and whether other clinical indicators are more predictive.
Methods: We prospectively evaluated 327 patients (79% M, 67±11 y) with CAD, LVEF ≤35% (mean, 23±7%), and an implanted cardioverter-defibrillator (ICD). Baseline clinical data were collected, and ECG measurements were taken using validated GE Healthcare algorithms. Tpe was corrected for HR via Tpe/√RR (abbreviated Tpec). Follow-up for appropriate ICD therapy for VT or VF was conducted via chart review and device interrogation.
Results: Over a mean follow-up of 17±12 months, 61 (19%) pts had appropriate ICD therapy. Univariate predictors of events were Tpec (mean, 108±23 ms; RR per 10 ms increase: 1.19 [1.06–1.34], p=0.003), QTc (mean, 460±38 ms; RR per 10 ms: 1.07 [1.00–1.14], p=0.050), and Cornell voltage (mean, 17±11 mV; RR per 1 mV: 1.03 [1.01–1.05], p=0.009). Variables not predicting events (all p>0.05) included: Q-Tpeak duration, QRS duration, LBBB, Sokolow-Lyon voltage, heart rate, LVEF, BMI, systolic or diastolic BP, age, sex, HF class, smoking status, renal function, and use of a variety of medications. On multivariable analysis, Tpec and Cornell voltage remained significantly predictive (adjusted RR: 1.18 per 10 ms, p=0.005; and 1.03 per 1 mV, p=0.02; respectively) but QTc was no longer predictive (p=0.78).
Conclusions: In conclusion, in patients with CAD and a depressed LVEF, Tpecand Cornell voltage each independently predict appropriate ICD therapy, but several other candidate variables are not predictive.
- © 2010 by American Heart Association, Inc.