Myocarditis is an inflammatory disease of the myocardium caused by infectious factors such as viruses and bacteria, or non-infectious factors such as drugs and poisons. Severe myocarditis is defined as myocarditis with serious complications such as heart failure, cardiogenic shock, high degree of atrioventricular block or sinus node impairment. Severe myocarditis is rare, and often develops because of failure to receive standardized treatment in a timely manner, overwork during the illness, and so on. Patients with severe myocarditis may have heart failure manifestations such as chest tightness, chest pain, dyspnea, edema, etc.; they may also have signs of cardiogenic shock such as drop in blood pressure, cold extremities, etc.; when there is a high degree of atrioventricular block or impairment of sinus node function, it will lead to cerebral blood supply insufficiency, which will lead to fainting or obvious low blood pressure. Severe myocarditis progresses rapidly and has a high mortality rate, so it is important to follow the doctor’s instructions to carry out active treatment, so as not to delay the condition and cause adverse consequences.