Relationship between T-wave alternans magnitude and T-wave amplitude before the onset of ventricular tachyarrhythmias during emergent reperfusion in acute coronary syndrome patients
Year: 2011
Type: letter
Abstract: We greatly appreciate Dr Madias’ remarks on our recent study demonstrating the usefulness of continuous T-wave alternans (TWA) monitoring in ultra-short-term prediction of impending life-threatening ventricular tachyarrhythmias (VTA) during emergent reperfusion therapy in acute coronary syndrome (ACS) patients.1 He raised an interesting question, namely, was there a relationship between the increase in TWA and the possible increase in T-wave amplitude prior to the occurrence of VTA?2 This question is based on his theory that TWA magnitude is affected by T-wave amplitude and should therefore be corrected.3 We evaluated the relationship between TWA magnitude and the corresponding T-wave amplitude (absolute value), both of which were reported for each 15 s of data in modified V1 and V5 leads in the three ACS patients with VTA. Data with noise levels >20 μV or obtained during atrial fibrillation, high-grade atrioventricular block, or paced rhythm were excluded from the analysis. Pearson's correlation was applied to the regression analysis. The data were considered statistically significant when the two-tailed P value was <0.05. There was no significant positive correlation between TWA magnitude and the corresponding T-wave amplitude in either modified V1 or V5 leads in the two patients with ventricular fibrillation or in the patient with sustained ventricular tachycardia (VT). There was a weak negative correlation in modified V5 lead in the patient with VT (Figure 1). These results indicate that the upsurge in TWA before the onset of VTA was not merely a consequence of increased T-wave amplitude but provided a measure of the degree of cardiac electrical instability provoked by myocardial ischaemia-reperfusion. Relationship between T-wave alternans magnitude and the corresponding T-wave amplitude in modified V1 and V5 leads in the three patients with ventricular tachyarrhythmias. (A) Patient with non-ST-segment elevation myocardial infarction and sustained ventricular tachycardia. (B) Patient with ST-segment elevation myocardial infarction and ventricular fibrillation. (C) Patient with unstable angina and ventricular fibrillation. There was no significant positive correlation between T-wave alternans magnitude and the corresponding T-wave amplitude. A weak negative correlation was found in modified V5 lead in patient (A). TWA, T-wave alternans; NS, not significant. We agree that TWA monitoring deserves further evaluation as an independent risk predictor of VTA in ACS patients. Conflict of interest: R.L.V. is an inventor of the Modified Moving Average method for T-wave alternans analysis with patent assigned to Beth Israel Deaconess Medical Center and licensed by GE Healthcare Inc. and Medtronic Inc.
Source: EP Europace
Language: English
Subfield: Cardiology and Cardiovascular Medicine
Field: Medicine
Domain: Health Sciences
Open Access status: bronze
OpenAlex ID: W2030452047