Coronary microvascular dysfunction in Takotsubo syndrome: cause or consequence.

Takotsubo syndrome (TS) is an acute cardiac disease entity, characterized by a transient myocardial stunning in a distinctive predominantly regional circumferential pattern. One of the discussed pathological mechanisms of TS is coronary ischemia including coronary microvascular dysfunction (CMVD). Many studies have revealed invasive or non-invasive signs of CMVD in patients with TS, and therefore some investigators believe that CMVD is the primary cause of TS. Nevertheless, other studies have not shown any sign of CMVD. In addition, those studies, which have shown signs of CMVD, do not reveal such signs in all the three coronary vessel distribution; some of the patients show signs of CMVD in two or only one coronary artery territory. Moreover, signs of CMVD in TS are more prevalent and more pronounced in the left anterior descending artery (LAD) distribution. The CMVD in TS is reversible in a pattern parallel to the improvement of myocardial wall motion abnormality. In this review, substantial evidences challenging CMVD as the primary cause of TS and supporting the concept that CMVD is a secondary or epiphenomenon in TS are provided. Furthermore, convincing explanation is given for the causes of the more prevalent and the more pronounced signs of CMVD observed in the LAD distribution.