Cardiac injury can be divided into acute, subacute and chronic injury. Acute injury usually occurs at the time of drug administration; subacute injury may occur after 1-2 cycles of drug treatment; chronic injury is myocardial injury that occurs in 6-8 weeks, and it is subdivided into type I and type II. Type I is irreversible myocardial injury, mostly seen after chemotherapy, and type I is prone to congestive heart failure. Type II is reversible myocardial injury, which is manifested as cardiac depression, a temporary loss of function and decompensation, which can be slowly recovered afterwards. This is a type II cardiotoxic effect, seen after targeted therapy. It is most commonly caused by myocardial damage after the use of Herceptin, and it can recover gradually. In the case of other myocardial damage caused by chemotherapeutic agents like anthracyclines, it is irreversible.