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Use of the signal-averaged electrocardiogram in ischemic heart disease

Sanjiv M Narayan, MD, PhD
Michael E Cain, MD
Section Editor
Ary L Goldberger, MD
Deputy Editor
Brian C Downey, MD, FACC


Sudden cardiac arrest (SCA) leading to sudden cardiac death (SCD) is a common problem in developed countries that is predominantly due to ventricular tachycardia (VT) or ventricular fibrillation (VF). (See "Pathophysiology and etiology of sudden cardiac arrest".)

The signal-averaged electrocardiogram (SAECG) is a noninvasive technique that enables detection of the substrate for reentrant arrhythmias such as VT [1-4]. It has therefore been applied to the identification of individuals at risk for SCD, particularly in the context of coronary heart disease, healed myocardial infarction, or left ventricular dysfunction. (See "Clinical applications of the signal-averaged electrocardiogram: Overview".)

In patients with the substrate for VT, slowed conduction through myocardium — disrupted by inflammation, edema, fibrosis, or scar tissue — results in electrical potentials that extend beyond the activation time of normal surrounding myocardium but are too small for detection on the surface ECG. The SAECG uses computerized averaging of ECG complexes, obtained during sinus rhythm, to facilitate the detection of these small microvolt level signals as ventricular late potentials (figure 1). It is possible that the signals identified by the SAECG, which are related to late potentials identified in patients with structural heart disease and used to guide VT ablation may also be identified by novel techniques [5,6]. (See "Technical aspects of the signal-averaged electrocardiogram".)

Use of the SAECG in patients with CHD will be reviewed here. The potential use of the SAECG in patients with nonischemic heart disease, syncope, cardiac transplantation, and arrhythmias are discussed separately. (See "Use of the signal-averaged electrocardiogram in nonischemic heart disease and cardiac transplantation" and "Use of the signal-averaged electrocardiogram in arrhythmia evaluation and management".)


Most patients with coronary heart disease (CHD) and sustained ventricular tachycardia (VT) or ventricular fibrillation (VF) will be treated with an implantable cardioverter-defibrillator for secondary prevention of SCD. In such patients, further risk stratification testing including the SAECG is not likely to impact management. Possible roles for the SAECG in such patients would include guidance of adjunctive antiarrhythmic therapy and the identification of patients with chronic stable CHD who might benefit from reperfusion.


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Literature review current through: Sep 2016. | This topic last updated: Jan 12, 2016.
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