Cardiac β-Adrenergic Receptor Downregulation, Evaluated by Cardiac PET, in Chronotropic Incompetence.

Goto, Toshihiko; Kikuchi, Shohei; Mori, Kento; Nakayama, Takafumi; Fukuta, Hidekatsu; Seo, Yoshihiro; Narita, Hitomi; Iida, Akihiko et al. · J Nucl Med · 2021

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Abstract

The mechanism of chronotropic incompetence (CTI), which has been associated with autonomic dysfunction, has not been elucidated in patients without heart failure (HF). <b>Methods:</b> Cardiac PET using <sup>11</sup>C-CGP12177 was performed to investigate the cardiac β-adrenergic receptor density (β-ARD) in 13 patients with CTI without HF and 6 healthy controls. The maximum number of available specific <sup>11</sup>C-CGP12177 binding sites per gram of tissue was calculated in regions of interest using an established graphical method. <b>Results:</b> Peak heart rate was significantly lower in CTI patients than in controls (116.9 ± 11.0 vs. 154.8 ± 14.4 beats/min, <i>P</i> < 0.001). β-ARD of the total myocardium was significantly lower in CTI patients than in controls (4.3 ± 1.7 vs. 7.0 ± 1.7 pmol/mL, <i>P</i> = 0.005). <b>Conclusion:</b> β-adrenergic receptor downregulation was demonstrated in patients with CTI without HF. Decreased β-ARD is a common feature in patients with CTI, with or without HF.

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