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. 1998 Sep;80(3):251–256. doi: 10.1136/hrt.80.3.251

Prognostic significance of electrical alternans versus signal averaged electrocardiography in predicting the outcome of electrophysiological testing and arrhythmia-free survival

A Armoundas 1, D Rosenbaum 1, J Ruskin 1, H Garan 1, R Cohen 1
PMCID: PMC1761106  PMID: 9875084

Abstract

Objective—To investigate the accuracy of signal averaged electrocardiography (SAECG) and measurement of microvolt level T wave alternans as predictors of susceptibility to ventricular arrhythmias.
Design—Analysis of new data from a previously published prospective investigation.
Setting—Electrophysiology laboratory of a major referral hospital.
Patients and interventions—43 patients, not on class I or class III antiarrhythmic drug treatment, undergoing invasive electrophysiological testing had SAECG and T wave alternans measurements. The SAECG was considered positive in the presence of one (SAECG-I) or two (SAECG-II) of three standard criteria. T wave alternans was considered positive if the alternans ratio exceeded 3.0.
Main outcome measures—Inducibility of sustained ventricular tachycardia or fibrillation during electrophysiological testing, and 20 month arrhythmia-free survival.
Results—The accuracy of T wave alternans in predicting the outcome of electrophysiological testing was 84% (p < 0.0001). Neither SAECG-I (accuracy 60%; p < 0.29) nor SAECG-II (accuracy 71%; p < 0.10) was a statistically significant predictor of electrophysiological testing. SAECG, T wave alternans, electrophysiological testing, and follow up data were available in 36 patients while not on class I or III antiarrhythmic agents. The accuracy of T wave alternans in predicting the outcome of arrhythmia-free survival was 86% (p < 0.030). Neither SAECG-I (accuracy 65%; p < 0.21) nor SAECG-II (accuracy 71%; p < 0.48) was a statistically significant predictor of arrhythmia-free survival. 
Conclusions—T wave alternans was a highly significant predictor of the outcome of electrophysiological testing and arrhythmia-free survival, while SAECG was not a statistically significant predictor. Although these results need to be confirmed in prospective clinical studies, they suggest that T wave alternans may serve as a non-invasive probe for screening high risk populations for malignant ventricular arrhythmias.

 Keywords: electrophysiological testing;  electrical alternans;  signal averaged electrocardiography;  arrhythmias

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Figure 1  .

Figure 1  

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Representative example of power spectrum of beat to beat fluctuations in T wave morphology. The alternans ratio is the amplitude of the spectrum at the alternans frequency (alternans peak) minus the mean background noise level (noise), divided by the standard deviation of the noise (noise) in the reference noise band.

Figure 2  .

Figure 2  

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Arrhythmia-free survival of patients with positive/negative electrophysiological testing (EP).

Figure 3  .

Figure 3  

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Arrhythmia-free survival of patients with positive/negative T wave alternans (TWA).

Figure 4  .

Figure 4  

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Arrhythmia-free survival of patients with positive/negative signal averaged electrocardiography (SAECG, one or two criteria).

Selected References

These references are in PubMed. This may not be the complete list of references from this article.

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