A Novel Disease Entity in Search of Its Own Identity　― Takotsubo Syndrome. Is It Really “Cardiomyopathy”? ―

Background: The term “takotsubo cardiomyopathy” is commonly used in clinical practice. However, there is conceptual problem with the term “cardiomyopathy” in this context because “cardiomyopathy” implies a primary and chronic myocardial disease of unknown etiology. In this study we reviewed the literature related to takotsubo cardiomyopathy to investigate whether it is appropriate to use the term “cardiomyopathy” for this condition. Methods and Results: A literature review revealed that this condition was originally described in 1990 in Japan as postischemic myocardial stunning with unique left ventricular apical ballooning and that it gradually gained global attention thereafter. Subsequently, the term “takotsubo cardiomyopathy” was introduced to describe this heart failure phenotype. However, this term has been called into question because several recent studies investigating the mechanism underlying this condition have provided evidence of myocardial ischemia possibly due to microvascular dysfunction. The term “takotsubo syndrome” was suggested to describe this microvascular acute coronary syndrome, which is in agreement with the original description of the condition as myocardial stunning following acute myocardial ischemia. Conclusions: Based on the accumulating evidence of acute myocardial ischemia due to microvascular dysfunction as the mechanism underlying this condition, in addition to the fact that the term “cardiomyopathy” literally implies a primary and chronic myocardial disease, it is advisable that the term “takotsubo syndrome” is used until the etiology and underlying mechanism of this condition are fully clarified.