abstract
presented
at the 1996 AHA
New Orleans, LA
November 11 - 13, 1996
Eectrical T-Wave
Alternans is Superior to QT or JT Dispersion as Predictive Marker
of Ventricular Arrhythmias
PUBLICATION DATA
Charles I. Berul, Paul J. Wang, Sharon L. Hill,
Victor C. Lee, N. A. Mark Estes III; New England Medical Center
Several non-invasive markers of ventricular
arrhythmias have been identified for evaluation of repolarization
abnormalities. Interlead QT and JT dispersion were compared with
electrical T-wave alternans (T-Alt) at rest and during exercise
testing in order to determine superior markers for arrhythmia
development in a high-risk adult population. T-Alt measures microvolt
beat-to-beat spectral variation in repolarization amplitude
whereas QT and JT dispersion represent regional heterogeneity
of repolarization duration. A group of 24 patients with
previous history of syncope, sudden death, or ventricular arrhythmias
were evaluated by multiple blinded observers using each of non-invasive
method. QT (or QTc) dispersion and JT (or JTc)
dispersion >100ms are standard deviation of dispersion mean
QT (or JT) >6 were considered positive. T -Alt voltage >1µV
at rest or > 1.9µV with exertion, or T-Alt ratio >3
was deemed positive by standard criteria. Clinical VT or VF,
or inducible VT at diagnostic EP study were predefined criteria
for arrhythmia vulnerability.
Results:
| Sensitivity | |||||
| Specificity | |||||
| PPV | |||||
| NPV |
Conclusions: In
this high-risk population, although both dispersion and T-Alt
are specific markers for arrhythmia risk, the T-Alt test has superior
sensitivity and predictive value, compared with ECG interlead
dispersion. Ventricular vulnerability may relate more to heterogeneity
of repolarization amplitude than duration.
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