Abstract

Background: Takotsubo cardiomyopathy (TC) is characterized by left ventricular apical ballooning and intact coronary arteries. The pathogenesis of this disorder is likely to be catecholamine-mediated myocyte damage, microvascular dysfunction and subsequent oxidative stress; however, a number of possible alternative theories have been suggested. Neopterin is produced by activated macrophages following stimulation by interferon-g produced by T-lymphocytes and is capable of enhancing the oxidative potential of reactive oxygen species. The aim of this study was to compare plasma neopterin levels between TC patients and patients with coronary artery disease. Methods: Plasma neopterin levels were measured on admission in patients with TC (n=37), stable angina pectoris (SAP, n=66), unstable angina pectoris (UAP, n=72) and acute myocardial infarction (AMI, n=67) using HPLC. A frozen myocardium specimen was obtained by biopsy from a patient with TC and stained for neopterin, macrophages, and microvessels using immunohistochemistry. Results: Plasma neopterin levels were significantly higher in TC patients compared with SAP patients ( P <0.0001) or UAP patients ( P <0.05), although they were not significantly different from those in AMI patients. In TC patients, plasma neopterin levels correlated positively with neutrophil count (R=0.47, P<0.05) and serum C-reactive protein levels (R=0.38, P<0.05). Immunohistochemical staining showed abundant neopterin-positive macrophages in the myocardium specimen from the patient with TC. Conclusions: This study demonstrates, for the first time, that plasma neopterin levels are elevated in TC patients compared with those in SAP and UAP patients. These findings suggest that neopterin may play an important role in the pathophysiology of Takotsubo cardiomyopathy.