"Indeterminate" Microvolt T-Wave Alternans Tests Predict High Risk of Death or Sustained Ventricular Arrhythmias in Patients With Left Ventricular Dysfunction
Elizabeth S. Kaufman, MD, FACC*,*,
Daniel M. Bloomfield, MD, FACC ,
Richard C. Steinman, AB,
Pearila B. Namerow, PhD,
Ottorino Costantini, MD*,
Richard J. Cohen, MD, PhD and
J. Thomas Bigger, Jr, MD
* Heart and Vascular Research Center, MetroHealth Campus of Case Western Reserve University, Cleveland, Ohio
Columbia University, New York, New York
Massachusetts Institute of Technology, Cambridge, Massachusetts
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Figure 1 Kaplan-Meier estimates of death or non-fatal sustained ventricular arrhythmia comparing patients with negative, positive, and indeterminate microvolt T-wave alternans (MTWA) results. The 2-year event rates were (bottom to top): negative 2.4%, positive 12.3%, and indeterminate 17.8%. There was no significant difference between the positive and indeterminate curves (log-rank test).
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Figure 2 Causes of indeterminate microvolt T-wave alternans (MTWA) tests. Only 6.4% of the indeterminate MTWA results were due to technical factors; the remainder were due to patient factors. BPM = beats/min; HR = heart rate.
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Figure 3 Kaplan-Meier estimates of death or non-fatal sustained ventricular arrhythmia at 2 years of follow-up, comparing subgroups of patients with indeterminate MTWA results and those with positive MTWA results. The 2-year outcome rates were (bottom to top): noise or rapid HR rise 0.0%, positive MTWA test 12.3%, HR <105 beats/min 14.2%, unsustained MTWA 21.8%, and excessive ventricular ectopy during exercise 27.2%. Abbreviations as in Figure 2.
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