Comparison of TWA Testing Technologies

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Comparison of TWA Testing Technologies

• Spectral Analysis MTWA
• vs
• Time Domain TWA
• (Comparison based on currently available
  information
• in the public domain)

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MTWA
TWA

• Technology

Analytic Spectral Method
Modified Moving Average Method
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MTWA
TWA

• Technology

Analytic Spectral Method
Modified Moving Average Method

• Technology Features

Measures subtle, visually imperceptible
alternans levels down to 1 microvolt
Measures only Visible alternans on the order
of tens of microvolts potential to misdiagnosis
patients
Proprietary smart multi-segment sensors allow
direct detection and reduction of motion
artifact or respiratory noise
Standard electrodes, incapable of direct
detection and reduction of motion artifact or
respiratory noise
Specialized exercise protocol and corresponding
Graphical User Interface for optimal detection of
MTWA
Lacks specialized exercise protocol. No guarantee
of optimal detection of MTWA
FDA approved automated interpretation capability
provides ease of use and increased accuracy for
detecting non-visible alternans
No automated interpretation capability.
Universal platform can be used with any platform
Dedicated platform can be used only with
GE/Marquette platforms
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MTWA
TWA

• Performance

Simulation
Detects alternans levels less than 0.1 microvolts
Detects alternans levels greater than 10
microvolts
Human subjects
Less than 1.9 microvolts of alternans for
negative subjects both at rest and peak exercise
More than 10 microvolts of alternans at rest for
both positive and negative patients at rest.
37.4 4.7 microvolts of alternans for negative
patients at peak exercise 55.7 5.5 of
alternans for positive patients at peak exercise
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Analytic Spectral Method vs. MMA
Method Comparison of the Clinical Performance 15
Patients with Ventricular Tachyarrhythmic Events
None of the events would be detected
95 of the events are detected
Data from Gold et al, (Labeling) study
Multi-center, prospective study of
313 patients referred for EP testing
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MTWA
TWA

• Performance

Simulation
Detects alternans levels less than 1 microvolts
Detects alternans levels grater than 10
microvolts
Human subjects
Less than 1.9 microvolts of alternans for
negative subjects both at rest and peak exercise
More than 10 microvolts of alternans at rest.
37.4 4.7 microvolts of alternans for negative
and 55.7 5.5 of alternans for positive
patients at peak exercise
Clinical Studies
More than 100 publications on clinical studies
with 5000 patients
No publication on clinical studies
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MTWA
TWA

• Indication for Use

Cambridge Heart alternans processing system is
intended for the measurement of Microvolt T-Wave
Alternans at rest and during ECG stress
testing. The presence of Microvolt T-wave
Alternans as measured by the Analytic Spectral
Method of the alternans processing system in
patients with known, suspected or at risk of
ventricular tachyarrhythmia predicts increased
risk of a cardiac event (ventricular
tachyarrhythmia or sudden death). The predictive
value of T-wave Alternans for cardiac events has
not been established in patients with active,
untreated ischemia. Microvolt T-wave Alternans
is defined as T-wave alternans which (a) is
measured from high-resolution multi-segment
sensors, (b) is present in leads X, Y, Z, VM or
two adjacent precordial leads, (c) is at the
level of 1.9 microvolts after signal optimization
and subtraction of the background noise level,
(d) is at least three standard deviations greater
than the background noise level, (e) has an onset
heart rate at or below 110 beats per minute, and
(f) is sustained for all heart rates above the
onset heart rate.
The T-Wave Alternans (TWA) Algorithm option is to
be used in a hospital, doctors office, or clinic
environment by competent health care
professionals for recording ST-T wave morphology
fluctuations for patients who are undergoing
Cardiovascular disease testing. The T-wave
alternans analysis is intended to provide only
the measurements of the fluctuations of the ST-T
waves. The T-Wave alternans measurements
produced by the T-Wave Alternans analysis are
intended to be used by qualified personnel in
evaluating the patient in conjunction with the
patients clinical history, symptoms, other
diagnostic tests, as well as the professionals
clinical judgment. No interpretation is
generated.
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MTWA
TWA

• Publications

More than 200 publications on spectral method
1 publication on MMA method

• Reimbursement
• CPT Code 93025
• Microvolt T-Wave Alternans for assessment of
  ventricular arrhythmias.

Methodology does not conform to description for
payment Methodology does not measure alternans at
required levels for payment

• In Medicare policies,
• description of payment for
• MTWA test is very specific to
• Analytic Spectral Method and/or
• Ability to measure as little as 1 microvolt