Treadmill exercise test (TET) is a commonly used method for assessing the risk of cardiac artery disease (CAD). However, the false positive rate of TET is more than 50%. The CI tester, which is a portable single-lead electrocardiogram, of Healthy Heart Technology Co. quantifies the degree of coherence between heart rhythm and breathing to reflect the phenomenon of cardiac ischemia. The false positive rate of TET can be reduced to 9.1% to assist clinicians in interpretation.