Electrocardiographic Arrhythmia Risk Testing Gregory Engel, MD, James G. Beckerman, MD, Victor F. Froelicher, MD, Takuya Yamazaki, MD, Henry A. Chen, MD, Kelly Richardson, MD, Ryan J. McAuley, BS, Euan A. Ashley, MD, Sung Chun, MD and Paul J. Wang, MD Abstract: Among the most compelling challenges facing cardiologists today is identification of which patients are at highest risk for sudden death. Automatic implantable cardioverter-defibrillators are now indicated in many of these patients, yet the role of noninvasive risk stratifica- tion in classifying patients at high risk is not well defined. The purpose of this review is to evaluate the various electrocardiographic (ECG) techniques that appear to have potential in assessment of risk for arrhythmia. The resting ECG (premature ventricular contractions, QRS duration, damage scores, QT dispersion, and ST segment and T wave abnormalities), T wave alternans, late poten- tials identified on signal-averaged ECGs, and heart rate variability are explored. Unequivocal evidence to support the widespread use of any single noninvasive technique is lacking; further research in this area is needed. It is likely that a combination of risk evaluation techniques will have the greatest predictive power in enabling identification of patients most likely to benefit from device therapy. (Curr Probl Cardiol 2004;29:357-432.) O ver the past decade advances in technology have provided cardiologists with improved therapeutic options for patients at risk for sudden cardiac death (SCD). The automatic implantable cardioverter-defibrillator (ICD) has changed the landscape of electrophys- The authors have no conflicts of interest to disclose. 0146-2806/$ – see front matter doi:10.1016/j.cpcardiol.2004.02.007 Curr Probl Cardiol, July 2004 365