Key result
Chronotropic incompetence without heart failure was associated with significantly lower cardiac beta-adrenergic receptor density in the total myocardium compared to healthy controls (4.3 vs. 7.0 pmol/mL).
Why the study?
The mechanism of chronotropic incompetence, associated with autonomic dysfunction, has not been elucidated in patients without heart failure.
Does chronotropic incompetence without heart failure associate with decreased cardiac β-adrenergic receptor density compared to healthy controls?
Case-Control (n=19)
No
Does chronotropic incompetence without heart failure associate with decreased cardiac β-adrenergic receptor density compared to healthy controls?
Absolute Event Rate: 4.3% vs 7%
p-value: p=0.005
Cardiac β-adrenergic receptor downregulation is present in patients with chronotropic incompetence without heart failure, suggesting a common pathophysiological mechanism regardless of heart failure status.
Hypothesis-generating for β-ARD in non-HF chronotropic incompetence; should not yet change practice or guide therapy.
The mechanism of chronotropic incompetence (CTI), which has been associated with autonomic dysfunction, has not been elucidated in patients without heart failure (HF). Methods: Cardiac PET using ¹¹C-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 ¹¹C-CGP12177 binding sites per gram of tissue was calculated in regions of interest using an established graphical method. Results: Peak heart rate was significantly lower in CTI patients than in controls (116.9 ± 11.0 vs. 154.8 ± 14.4 beats/min, P < 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, P = 0.005). Conclusion: 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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Goto et al. (2020) conducted a case-control in Chronotropic incompetence without heart failure (n=19). Chronotropic incompetence vs. Healthy controls was evaluated on Cardiac beta-adrenergic receptor density (b-ARD) of the total myocardium (p=0.005). Chronotropic incompetence without heart failure was associated with significantly lower cardiac beta-adrenergic receptor density in the total myocardium compared to healthy controls (4.3 vs. 7.0 pmol/mL).
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