2292/C47 - Negative Microvolt T
Wave Alternans Test Results after Antiarrhythmic Drugs do not Predict
Recurrence of Ventricular Tachycardia |
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Keywords: |
Ventricular
tachycardia, Antiarrhythmic agents, Electrophysiology, Follow-up studies,
Sudden death |
Disclosure Block: |
K. Tanno, None; H. Ito, None; F. Miyoshi, None; Y. Minoura, None; M. Kawamura, None; T. Asano, None; Y. Kobayashi, None. |
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Abstract:
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Microvolt
T-wave alternans (MTWA) is reported to be closely associated with sudden
cardiac death and ventricular tachyarrhythmia (VT) in patients with organic
heart disease (OHD). The purpose of this study was to determine whether
negative MTWA test results after antiarrhythmic drugs (AAD) administration
indicates that VT will not recur. Methods: Subjects were 31 patients
(men/women=27/4, mean age=60±13 years) who had OHD and sustained VT. They
underwent MTWA testing before and after AAD administration. MTWA recordings
were made with the CH2000 system (Cambridge Heart, MA) with the patient in
sinus rhythm and under high right atrial pacing at 90, 100, 110, and 120
beats per minute (bpm) if conduction proceeded without atrioventricular block
for more than 3 minutes at each pacing rate. MTWA was considered positive
when alternans voltage was more than 1.9 microvolts and the alternans ratio
was greater than 3 for more than 1 minute in VM, X, Y, Z, or two adjacent
precordial leads without artifact at a heart rate of less than 110 bpm. MTWA
was considered negative if the criteria for a positive test were not met, if
there was no significant alternans for 1 minute while the heart rate was
greater than 100 bpm, or if the tracing was not obscured by noise or ectopic
beats. Otherwise, TWA was considered indeterminate. The date of the last TWA
test was regarded as day 1 of the study, and patients were followed up
prospectively at our university hospital outpatient clinic every month. The
endpoint of the study was the combined incidence of sustained VT, VF,
appropriate ICD therapy with pacing or shocks, or SCD. Results: Positive MTWA
was 17 patients before AAD administration. In 6 of 17 patients, positive MTWA
changed into negative MTWA after administration of amiodarone. In comparison
of MTWA-positive and MTWA-negative patients after AAD administration, there
was no significant difference in age, ejection fraction or frequency of
positive SAECG. During 20 months follow-up periods, the incidence of VT
recurrence or SCD was not different between patients with positive TWA and
negative TWA. Conclusion: Negative MTWA after AAD does not predict any
recurrence of VT or SCD in patients with OHD. |