Short-term reproducibility of T wave alternans measurement.
BACKGROUND
Microvolt T wave alternans (TWA) has been proposed as a strong independent predictor of malignant ventricular tachyarrhythmias and sudden cardiac death. TWA reproducibility during bicycle stress test has not been previously investigated. We sought to assess the short-term reproducibility of TWA, as well as heart rate (HR) threshold for TWA, and its spatial distribution and magnitude.


RESULTS
The study enrolled 42 patients who were able to complete two bicycle stress tests with HR at peak exercise >110 beats/min within 4 hours of each other and who had technically adequate recordings for TWA analysis during both tests. Concordant results for TWA determination were obtained in 39 (93%) of 42 cases. TWA was present during both tests in 23 patients and was absent during both tests in 16 patients. In the 23 patients with two positive tests, HR at the onset of TWA was not significantly different during the two tests. Further, the number of leads showing TWA and the magnitude of TWA were not significantly different between the two tests.


CONCLUSIONS
TWA is characterized by satisfactory short-term reproducibility and, when present, by high temporal and spatial stability.
Turitto
Gioia
G
Department of Medicine, State University of New York-Downstate Medical Center, Brooklyn 11203, USA. gturitto@aol.com
Mirandi
Anthony P
AP
Pedalino
Ronald P
RP
Uretsky
Scott
S
El-Sherif
Nabil
N
D016757:Death, Sudden, Cardiac / Q000517:prevention & control*; D004562:Electrocardiography / Q000379:methods*; D005080:Exercise Test; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D017180:Tachycardia, Ventricular / Q000175:diagnosis* / Q000503:physiopathology