Why the study?
The clinical utility of microvolt T-wave alternans for risk stratification of life-threatening ventricular arrhythmias and guiding therapy remains uncertain despite extensive study.
Does Microvolt T-wave alternans (TWA) testing provide useful risk stratification for life-threatening ventricular arrhythmias and sudden cardiac death?
Does Microvolt T-wave alternans (TWA) testing provide useful risk stratification for life-threatening ventricular arrhythmias and sudden cardiac death?
Captured external expert commentary on this paper, strongest first. Original sources are linked where available.
“At the present time, I would be very leery at not implanting a defibrillator in a patient who meets MADIT II criteria solely on the results of T-wave alternans.”
“in clinical practice, a positive MMA-based TWA test as defined in the study probably would not have enough predictive value to assign high-risk status--and especially not enough to indicate device therapy--in patients like those his group studied. That, he said, would probably take a combination of TWA with other SCD risk markers.”
“Even if Drs Hohnloser and Cohen were correct that microvolt T-wave alternans (MTWA) testing predicts outcome, its overall utility would still be very limited as half of consecutive, 'real-world', heart failure (HF) patients are ineligible for, or cannot undertake, the test.”
This consensus guideline establishes microvolt T-wave alternans as a validated prognostic marker for cardiovascular and arrhythmic death, while noting it is not yet proven to independently guide therapeutic decisions such as ICD implantation.
This consensus guideline was prepared on behalf of the International Society for Holter and Noninvasive Electrocardiology and is cosponsored by the Japanese Circulation Society, the Computers in Cardiology Working Group on e-Cardiology of the European Society of Cardiology, and the European Cardiac Arrhythmia Society. It discusses the electrocardiographic phenomenon of T-wave alternans (TWA) (i.e., a beat-to-beat alternation in the morphology and amplitude of the ST-segment or T-wave). This statement focuses on its physiological basis and measurement technologies and its clinical utility in stratifying risk for life-threatening ventricular arrhythmias. Signal processing techniques including the frequency-domain Spectral Method and the time-domain Modified Moving Average method have demonstrated the utility of TWA in arrhythmia risk stratification in prospective studies in >12,000 patients. The majority of exercise-based studies using both methods have reported high relative risks for cardiovascular mortality and for sudden cardiac death in patients with preserved as well as depressed left ventricular ejection fraction. Studies with ambulatory electrocardiogram-based TWA analysis with Modified Moving Average method have yielded significant predictive capacity. However, negative studies with the Spectral Method have also appeared, including 2 interventional studies in patients with implantable defibrillators. Meta-analyses have been performed to gain insights into this issue. Frontiers of TWA research include use in arrhythmia risk stratification of individuals with preserved ejection fraction, improvements in predictivity with quantitative analysis, and utility in guiding medical as well as device-based therapy. Overall, although TWA appears to be a useful marker of risk for arrhythmic and cardiovascular death, there is as yet no definitive evidence that it can guide therapy.
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Verrier et al. (2011) conducted a review in Risk for life-threatening ventricular arrhythmias. Microvolt T-Wave Alternans (TWA) testing was evaluated. Microvolt T-wave alternans appears to be a useful marker of risk for arrhythmic and cardiovascular death, but there is no definitive evidence from interventional trials that it can independently guide therapy.
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