Abstract
Surge of T-Wave Alternans in the Absence of Heart-Rate Acceleration: A New Predictor of Sustained Ventricular Tachyarrhythmias in Patients with Low Ejection Fraction?
Heart rhythm, Vol.9(11), pp.1920-1920
11/2012
DOI: 10.1016/j.hrthm.2012.09.121
Abstract
T-wave alternans (TWA), a proarrhythmic form of repolarization instability, is usually observed in the setting of increased heart rate (HR). It is unknown, however, whether TWA can occur in the absence of HR acceleration before the onset of spontaneous, sustained ventricular tachyarrhythmia (VTA).
We examined ambulatory ECGs with spontaneous, sustained (>30 seconds, rate >100 bpm) VTA during 1 hour before the event; 34 patients had continuous, beat-to-beat HR and TWA data for ≥60 minutes (21% female, 65 ± 8 years; 87% had ischemic heart disease; ejection fraction [EF] 32 ± 17%). The data were averaged in 10-minute intervals. For consistency, TWA was analyzed using both spectral and time-domain methods as previously described.
Overall, both HR and TWA increased in the hour before the event in the studied group. Sixteen patients (47%) had concomitant increase in HR and TWA. In 10 patients (29%), TWA increased without HR acceleration (HR-independent TWA). These patients had a twofold lower EF than the rest of the patients (median EF: 15% and 35%; interquartile ranges of EF: 27% and 22%, respectively, P = .018). The time of occurrence, duration, and cycle length of the events associated with HR-independent TWA were similar to those for the rest of the events.
An isolated increase in TWA in the absence of HR acceleration precedes the onset of VTA in patients with low EF. Chronically enhanced sympathetic activity and exhausted repolarization reserve may contribute to this phenomenon. Predictive value of HR-independent TWA warrants further study.
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Details
- Title: Subtitle
- Surge of T-Wave Alternans in the Absence of Heart-Rate Acceleration: A New Predictor of Sustained Ventricular Tachyarrhythmias in Patients with Low Ejection Fraction?
- Creators
- V. Shusterman - University of PittsburghB. London - University of Iowa
- Resource Type
- Abstract
- Publication Details
- Heart rhythm, Vol.9(11), pp.1920-1920
- Publisher
- Elsevier Inc
- DOI
- 10.1016/j.hrthm.2012.09.121
- ISSN
- 1547-5271
- eISSN
- 1556-3871
- Language
- English
- Date published
- 11/2012
- Academic Unit
- Molecular Physiology and Biophysics; Cardiovascular Medicine; Internal Medicine
- Record Identifier
- 9984302994202771
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