Interpretation

At the conclusion of a Microvolt T-Wave Alternans (MTWA) Test, the Alternans Report Classifier generates an individual patient report. This detailed report provides a graphical representation of the magnitude of Microvolt T-Wave Alternans over the duration of the diagnostic session including rest, exercise, and recovery.

The system provides the classification parameters and clinical interpretation and suggests how a determinate test can be obtained if the result is indeterminate.

The report also provides an indication of potential artifacts including those caused by patient movement, respiration and ectopic beats.

How the system interprets and classifies the Microvolt T-Wave Alternans test report as positive, negative, or indeterminate requires a determination of whether Microvolt T-Wave Alternans is present, and if it is present, is it sustained or consistently present above the threshold heart rate which is referred to as onset heart rate.

When a test is classified as positive this indicates the presence of sustained alternans below the predetermined threshold heart rate of 110 bpm.

For a test to be negative, this requires that there is a minute above a heart rate of 105 bpm without any significant Microvolt T-Wave Alternans that is free of artifact that could potentially obscure Microvolt T-Wave Alternans.

All other tracings are classified as indeterminate. Patients who have an indeterminate test should be retested immediately. Studies indicate that over 50% of patients who initially test as indeterminate, become determinate if retested during the same session.

Though the system provides automatic interpretation, this simple flow chart (image of the flow chart from Interpretation CD) demonstrates how the user can easily interpret each Microvolt T-Wave Alternans test.

Interpretation Tutorial Program

The MTWA tutorial program provides additional information and instruction on interpreting the Microvolt T-Wave Alternans test. The tutorial reviews the basics of Microvolt T-Wave Alternans including an overview of MTWA and the methodology by which MTWA is measured. The program introduces the alternans reports and its different components and explains the classification rules in detail. It ends with a review of several example reports and demonstrates the process of interpretation.