Takotsubo or stress cardiomyopathy: role of nuclear cardiology using¹²³I-MIBG

Abstract

Takotsubo cardiomyopathy, also known as broken heart syndrome or stress cardiomyopathy, is a very interesting syndrome of acute transient left ventricular dysfunction, usually following significant emotional stress. It was first described in Japan nearly two decades ago and many aspects of its pathogenesis still remain poorly understood. The incidence of out-of-hospital sudden death related to Takotsubo is currently unknown. Excess catecholamines following stress seem to trigger Takotsubo and play an important role. The clinical presentation resembles acute myocardial infarction, including chest tightness and/or dyspnea, ECG changes and elevated cardiac enzymes. However, in contrast to a typical acute myocardial infarction, no significant coronary lesions or thrombi are found on coronary angiography. Differentiating Takotsubo from acute myocardial infarction is important to avoid the unnecessary risks of thrombolytic therapy. Typically, left ventriculography shows marked abnormalities with akinesia in the mid-distal anterior wall and apex (occasionally involving other heart regions), giving a balloon shape to the left ventricle. The name Takotsubo originates from the shape of the left ventricle, which resembles a Japanese octopus-trapping pot. Hospital mortality is low but death can be caused by severe acute heart failure and/or ventricular arrhythmias. Typically, a stressful life event is reported preceding the acute symptoms. Takotsubo is most common in menopausal women although young individuals, including men, can also be affected. The autonomic nervous system has a defined role in the process. In this article, we will review the role of imaging the heart using (123)I-meta-iodobenzylguanidine, a radioactive marker allowing mapping of the autonomic nervous system of the heart, in cases of suspected Takotsubo.

TakoTsubo Cardiomyopathy A Short Review

“…There is decreased uptake of 123 I-MIBG in areas of myocardial stunning. Villarroel et al demonstrated a case of typical TCM and performed 123 I-MIBG for the patient [32]. These were performed 10 days after the acute onset of symptom.…”

“…This showed typical decreased uptake of 123 I-MIBG in the distal anterior and inferior wall and apex, corresponding to the akinetic segments on left ventriculography. Rest 99m Tc-sestamibi images performed the following day for comparison show normal uptake in areas of decreased 123 I-MIBG, therefore 123 I-MIBG can be seen, notably from the inferior wall and apex [32]. These are typical features of TCM on nuclear scanning.…”

Possible Participation of Endothelial Cell Apoptosis of Coronary Microvessels in the Genesis of Takotsubo Cardiomyopathy

“…or physical stress. 6,7 Coronary spasm, 1 catecholamine cardiotoxicity, 8 and neurogenic stunned myocardium 9,10 have been proposed as causative mechanism(s).…”

Serial evaluation of left ventricular contraction and relaxation in Takotsubo cardiomyopathy by 2D speckle tracking echocardiography

“…According to their report, the excess levels of circulating catecholamine following physical and/or mental stress trigger activation of the beta-2 adrenoceptor and Gi protein signaling pathway, and exert a negative inotropic effect on the apical myocardium, in which the beta-2 adrenoceptor density is greater than that in the basal myocardium. Furthermore, it has been recognized that myocardial scintigraphy using 123 I-metaiodobenzylguanidine, a radioactive marker allowing mapping of the autonomic nervous activity of the heart, is the most sensitive examination for detecting sympathetic denervation in the apical myocardium in this syndrome [15]. We cannot perform myocardial scintigraphy repeatedly at bedside because this examination has a high medical cost and is not a portable examination.…”