Abstract 2292: Negative Microvolt T Wave Alternans Test Results after Antiarrhythmic Drugs do not Predict Recurrence of Ventricular Tachycardia
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.