Evaluation of Microvolt T-Wave Alternans(MTWA) Testing for the Detection of Active Ischemia

Ischemia, a common trigger for arrhythmias, is a well-documented cause of repolarization
alternans. Human studies have shown that active ischemia can be associated with visible as
well as microvolt-level T-wave alternans. While MTWA testing is traditionally used to
evaluate arrhythmic risk, this known association with ischemia may allow MTWA testing to be
used as a diagnostic tool to detect underlying CAD. The MTWA-CAD study will assess the
feasibility of this concept by measuring MTWA during routine nuclear stress testing or
stress echocardiography with treadmill exercise. This is a feasibility study designed to
verify preliminary observations under controlled environments and to generate hypotheses,
endpoints, and sample sizes for future investigations.

Inclusion Criteria:

- Age 18 or above, or of legal age to give informed consent specific to state and
national law

- Willing and capable of providing informed consent

- Willing and capable of undergoing a SPECT MPI exercise test (or stress echo) at an
approved clinical investigational center

- In normal sinus rhythm at the time of the exercise test

- A life expectancy of more than 6 months

Exclusion Criteria:

- In atrial fibrillation at the time of the exercise test

- Left bundle branch block (precludes ST segment measurement)

- Pacemaker-dependent

- Life expectancy of less than 6 months

- Pregnancy