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Electrical alternans and vulnerability to ventricular arrhythmias
D S Rosenbaum1, L E Jackson, J M Smith
1Cardiac Unit, Massachusetts General Hospital, Boston.
The New England Journal of Medicine
|January 27, 1994
Summary
Electrical alternans, a subtle beat-to-beat electrocardiogram change, predicts ventricular arrhythmias. This finding suggests electrical alternans may serve as a noninvasive marker for arrhythmia risk.
Area of Science:
- Cardiology
- Electrophysiology
- Medical Diagnostics
Background:
- Electrical alternans, characterized by alternating amplitude on electrocardiograms, is linked to ventricular arrhythmias but its prognostic value is unclear.
- The physiological significance and predictive implications of electrical alternans in clinical settings require further investigation.
Purpose of the Study:
- To determine if electrical alternans is a marker for vulnerability to ventricular arrhythmias.
- To investigate the prognostic implications of electrical alternans in patients undergoing electrophysiologic testing.
Main Methods:
- Developed a technique to detect subtle electrical alternans not visible on standard electrocardiograms.
- Prospectively studied 83 patients, correlating alternans levels with electrophysiologic testing outcomes and arrhythmia-free survival.
Main Results:
- Low-level electrical alternans (< 15 microV) during repolarization (ST segment and T wave) predicted inducible arrhythmias (81% sensitivity, 84% specificity).
- T-wave alternans and arrhythmia inducibility were significant predictors of arrhythmia-free survival.
- Patients with T-wave alternans had significantly lower 20-month arrhythmia-free survival (19%) compared to those without (94%).
Conclusions:
- Subtle electrical alternans involving the ST segment and T wave is prevalent in patients at high risk for ventricular arrhythmias.
- Electrical alternans detected on the electrocardiogram can serve as a noninvasive indicator of susceptibility to ventricular arrhythmias.