Sinus bradycardia and T-wave changes are cardiac vectorial changes shown on the electrocardiogram, usually due to myocardial lesions or changes in the heart’s systolic rhythm, resulting in bradycardia and a series of cardiac insufficiencies in blood supply. Sinus bradycardia with T-wave changes can be caused by the following factors: 1) neurohumoral endocrine factors, such as high tension of the vagus nerve, cold stimulation, poor rest and sleep, and late nights. 2) organic lesions of the heart, such as unstable angina pectoris in coronary artery disease, or changes in the myocardium or heart valves. The above-mentioned conditions can occur when there are unstable angina pectoris in coronary artery disease, or changes in the heart muscle or heart valves.