First is the electrocardiogram, which can show STT changes, including mild ST segment shift and T wave inversion, and various arrhythmias, especially ventricular arrhythmias and atrioventricular conduction blocks. Next is the cardiac ultrasound, also known as echocardiography, which can be normal or show left ventricular enlargement, reduced left ventricular motion, and decreased left ventricular systolic function. Another method is cardiac MRI, which mainly shows evidence of cardiac damage, and this has significant implications for the diagnosis of myocardial conditions. Additionally, biochemical tests include elevated cardiac enzymes, troponin, accelerated erythrocyte sedimentation rate, and other non-specific inflammatory markers. Moreover, there is cardiac biopsy, which is generally invasive and thus mainly used in patients with severe conditions, poor treatment response, or unknown causes. This test is generally not used in patients with mild symptoms. Other tests include chest X-rays and etiological examinations.