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