Myocardial fibrosis often occurs after myocardial infarction, cardiomyopathy disease, especially restrictive cardiomyopathy, long-term atrial fibrillation caused by myocardial fibrosis and other myocardial pathological processes, a large number of clinical studies have shown that the degree of myocardial fibrosis is closely related to the prognosis of patients, myocardial infarction patients in the recovery process, will occur in varying degrees of myocardial fibrosis, has occurred in the fibrosis of the myocardium leads to irreversible recovery of myocardial cells, myocardial Myocardial systolic and diastolic dysfunction after fibrosis, eventually causing heart failure. In myocardium that has undergone fibrosis, a potential difference is generated between fibrotic myocardium and normal myocardium, and there are often small islands of surviving myocardium between myocardial infarction surviving myocardium and myocardial fibrosis, and small islands are the pathological basis for the occurrence of arrhythmias, and this phenomenon is often considered to be related to sudden cardiac death, and early myocardial late potentials also indicate this, and the new myocardial fibrosis detection method, myocardial nuclear magnetic imaging can clarify whether there is myocardial fibrosis, which is of great significance in guiding the diagnosis or timely treatment of arrhythmias and preventing sudden death.