MTWA-CAD is a feasibility study designed to evaluate Microvolt T-Wave Alternans (MTWA) testing for the purpose of detecting active ischemia in patients with known or suspected coronary artery disease (CAD). MTWA is a subtle, alternating pattern in the T wave portion of the surface electrocardiogram (ECG) that is associated with increased risk of ventricular tachyarrhythmias and sudden cardiac arrest (SCA).