Objective: The aim of this study was to evaluate the effect of cardiac shock wave therapy (CSWT) on microvolt T wave alternans (MTWA) in patients with coronary artery disease (CAD). Methods: 87 patients with old myocardial infarction (OMI) were enrolled in this study. Sixty-two patients were randomized into the CSWT group, 32 patients into the regular treatment group (Group A) according to different shock wave procedure, and 30 into the expanding scope treatment group (Group B), and 25 patients were randomized into the control group (Group C). But the shock wave (SW) energy was only applied to the patients in the CSWT group and not to the patients in the control group. Three months was a treatment course, thus patients received a total of 9 CSWT treatment sessions. Results: Technetium-99m sestamibi myocardial perfusion, fluorine-18 fluorodeoxyglucose myocardial metabolism single-photon emission computed tomography (SPECT) were performed to identify segments of myocardial ischemia, myocardial viability, and microvolt T wave alternans (MTWA) before and after CSWT. After CSWT, the rehospitalization rates of CSWT group were lower than control group (P<0.05). The myocardial ischemic segments, metabolism abnormal segments, total radioactive score of perfusion imaging and metabolism imaging, MTWA, and MTWA/ HR in CSWT group were reduced significantly (P<0.05). And the heart rate of maximum MTWA, exercise time were increased significantly (P<0.05). All of the parameters in the control group did not change significantly even worsen after the treatment (P>0.05). Conclusions: CSWT can reduce the MTWA value, improve the heart chronotropic function and increase the threshold of frequency which causes MTWA.