123I-MIBG myocardial scintigraphy in patients with "takotsubo" cardiomyopathy.
The clinical characteristics of reversible left ventricular dysfunction due to "takotsubo" cardiomyopathy have been described, but the origin of this condition remains unclear. This study investigated (123)I-metaiodobenzlguanidine ((123)I-MIBG) myocardial scintigraphy in patients with takotsubo cardiomyopathy.


METHODS
Eight consecutive patients with takotsubo cardiomyopathy were studied. Left ventricular wall motion was monitored by echocardiography until wall motion normalized. (123)I-MIBG myocardial scintigrams were performed within 3 d of admission (0 mo) and after the improvement of left ventricular dysfunction (3 mo). Early images were obtained at 30 min after radioisotope injection and delayed images were obtained after 4 h. The heart-to-mediastinum ratio (H/M ratio) and the washout rate were calculated.


RESULTS
The mean left ventricular ejection fraction improved significantly (from 42.8% +/- 8.7% to 66.5% +/- 7.9%; P < 0.0001) and normalized after 19.4 +/- 5.4 hospital days. The early H/M ratio was significantly higher than the late ratio at 0 mo (2.16 +/- 0.25 vs. 1.89 +/- 0.24, respectively; P < 0.05), but not at 3 mo. The washout rate was significantly greater at 0 mo than at 3 mo (39.1% +/- 10.2% vs. 25.4% +/- 6.3%, respectively; P < 0.05).


CONCLUSIONS
In patients with takotsubo cardiomyopathy, initial (123)I-MIBG myocardial scintigraphy depicted a unique pattern of ventricular asynergy and indicated the existence of cardiac sympathetic hyperactivity, although coronary blood flow was maintained. These findings strongly suggest that takotsubo cardiomyopathy could be caused by neurogenic myocardial stunning.
Akashi
Yoshihiro J
YJ
Division of Cardiology, Department of Internal Medicine, St. Marianna University School of Medicine, Kawasaki, Japan. johnny@marianna-u.ac.jp
Nakazawa
Kiyoshi
K
Sakakibara
Masayoshi
M
Miyake
Fumihiko
F
Musha
Haruki
H
Sasaka
Kaoru
K
D019797:3-Iodobenzylguanidine; D000368:Aged; D009202:Cardiomyopathies / Q000175:diagnosis / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D008297:Male; D017682:Myocardial Stunning / Q000175:diagnosis / Q000000981:diagnostic imaging*; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013577:Syndrome; D018487:Ventricular Dysfunction, Left / Q000175:diagnosis / Q000000981:diagnostic imaging*
D019275:Radiopharmaceuticals; D019797:3-Iodobenzylguanidine