Signal‐Averaged Electrocardiogram: Update 1997

Abstract

Background: During the last 10 years, the signal-averaged electrocardiographic (SAECG) method has been proposed for a growing amount of clinical applications. As a screening method for increased risk of life-threatening ventricular arrhythmias it has demonstrated its value especially in risk stratification after myocardial infarction (MI) and in the evaluation of patients with unexplained syncope. Its value in risk prediction is now also proven in patients treated with thrombolytic therapy. Methods:In patients with dilated cardiomyopathy, hypertrophic cardiomyopathy, and arrhythmogenic right ventricular cardiomyopathy, the SAECG is helpful for detecting propensity to spontaneous ventricular tachycardia. P wave signal averaging has been demonstrated to identify patients with propensity to atrial arrhythmias, especially atrial fibrillation. Also, the diagnosis of sick sinus syndrome can be enhanced using this method.Results: So far, the use of SAECG in other patient populations except coronary heart disease has been very limited. However, the results of the recent studies recommend the utilization of this technique also in children and in the elderly, adjusting the findings with the effects of body size and age on the SAECG. Conclusions: The SAECG has a definite independent role in improving the predictive accuracy of conventional risk-evaluation techniques in patients with MI or cardiomyopathy. New patient populations like children and the elderly enlarge the number of patients benefiting of this method. New clinical applications of the SAECG method, such as detection of the propensity to atrial arrhythmias, ischemia and drug effects, are currently merging. Combining the time-and frequencydomain analysis of the SAECG with other methods relevant for the clinical problem is the way to optimize the use of this sophisticated noninvasive technique in clinical practice. A.N.E. 1997;2(4):384-393 signal-averaged electrocardiogram; dilated cardiomyopathy; arrhythmic cardiomyopathy; arrhythmogenic right ventricular cardiomyopathy Address for reprints: M. Makijawi, M.D.,

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“…They are also thought to represent delayed activation of damaged myocardium that serves as an anatomical substrate for repeated VA [40]. It has been shown that early pravastatin administration following thrombolytic therapy after an acute myocardial infarction led to a significant decrease in the incidence of ventricular late potentials [41].…”

“…Ventricular late potentials are low amplitude waveforms that correspond to fragmented activation of ventricular tissue and are considered to originate from areas of slow and inhomogenous conduction within the diseased myocardium [40]. They are also thought to represent delayed activation of damaged myocardium that serves as an anatomical substrate for repeated VA [40].…”