# Cardiac Nuclear Imaging Findings in Atypical Variants of Takotsubo Cardiomyopathy
## 4 Discussion and Limitations
\begin{table}
\begin{tabular}{c c c c c c} \hline
**Source, Year, Location, Type of Study** & \begin{tabular}{c} Number of Patients, \\ **Sea. Age** \\ \end{tabular} & TTC Variant & \begin{tabular}{c} **Cantile Nuclear Imaging** \\ **Technology** \\ \end{tabular} & \begin{tabular}{c} **Time Some Acute Event to first** \\ **Imaging/Edline Up** \\ \end{tabular} & \
\begin{tabular}{c} **Tanner Uptake in Involved** \\ **Segregation in New** \\ **Phase of Health-Up** \\ \end{tabular} \\ \hline [PERSON] et al., 2000, USA, case report [84] & 134, 9\(\sigma\) & arrows/inverted/basal & 9 th-Scientific-SPECT & NA/NP & reduced/NP \\ \hline Calend{tabular} & 11.48 \(\sigma\) & arrows/inverted/basal & 123I-mIBG-SPECT & NP/2 months & NP/reduced \\ \hline [PERSON] et al., 2013, Japan, letter to the & 115, 83\(\sigma\) & multivocalizer & 123I-mIBG-SPECT & 6 days/NP & reduced/NP \\ \hline [PERSON] et al., 2014, Japan, image focus [84] & 117, 74\(\sigma\) & multivocalizer & -2017 SPIECT & NA/NP & - normal/NP \\ \hline [PERSON] et al., 2015, Taiwan, image images [84] & 11.44 \(\sigma\) & arrows/inverted/basal TTC & 123I-mIBG-SPECT & NA/NP & reduced/NP \\ \hline [PERSON] et al., 2015, Taiwan, image image [84] & 11.44 \(\sigma\) & arrows/inverted/basal & 123I-mIBG-SPECT & NA/NP & reduced/NP \\ \hline [PERSON] et al., 2016, India, case report [84] & 11.44 \(\sigma\) & arrows/inverted/basal & 123I-mIBG-SPECT & NA/NP & reduced/NP \\ \hline [PERSON] et al., 2022, Japan, perspective study [75] & 6 \(\sigma\) and 24.56 [84; 85; 86; 87; 88; 89; 90] & arrows/inverted/basal & 9 th-Scientific-SPECT & 3.0 [2.30] days/35 [2.44] days &
\begin{tabular}{c} mild to moderately \\ reduced/reconstrained \\ cohort including patients with typical TTC. \\ \end{tabular} & Abbreviations: y. years; F. female; M. male; NA: not applicable; NP: not performed; *: data reflecting the total cohort including patients with typical TTC. \\ \hline \end{tabular}
\end{table} 
Table 1: Cont. nervous system and for studying the causes and effects of cardiac sympathetic hyperactivity [100; 101; 102]. In patients with TTC, the increased levels of plasma catecholamines inhibit neuronal norepinephrine uptake by presynaptic sympathetic endings [103], resulting in reduced signal in the involved segments of the left ventricle on 123I-mIBG scintigraphy [99; 104]. In 2005, [PERSON] et al. [89] observed the same discrepancies between long-chain fatty acid uptake assessed through 123I-BMIPP scintigraphy and cardiac innervation on 123I-mIBG scintigraphy, suggesting the existence of sympathetic nerve control on cardiac metabolism. Similarly, a large correlation between the location and extent of 123I-mIBG defects and reduced glucose metabolism is reported in the literature, suggesting that catecholamine-mediated myocardial insulin resistance as well as the inhibited intracellular translocation of glucose transporters (GLUT-4) by calcium overload may be responsible for the transient reduced 18F-FDG uptake in the hypokinetic areas [105; 106]. In addition, catecholamines exert a large vasoconstrtor effect potentially causing transient multivessel epicardial coronary spasm and microvascular dysfunction [107; 108; 109; 110; 111]. Cardiac nuclear imaging findings in atypical variants of TTC reflect literature data published for the typical apical form, but with different distribution patterns of uptake defects. In particular, the analysis of the selected papers showed normal perfusion in most publications, with a mild reduction reported only in a minority of papers [70; 71; 72; 73; 74; 75; 76; 77; 78; 79; 80; 81; 82; 83; 84], always followed by complete normalization on follow-up studies when performed [75; 76; 77]. Perfusion G-SPECT confirmed the presence of motion and thickness abnormalities, associated with a reduction in LVEF during the acute phase, in accordance with echocardiographic findings [72].