Key result
Patients with long-QT syndrome exhibited higher regional washout rates of [11C]mHED in the lateral left ventricle wall compared to healthy controls.
Why the study?
Does [11C]mHED-PET imaging reveal differences in cardiac presynaptic norepinephrine recycling in patients with long-QT syndrome compared to healthy controls?
Case-Control (n=45)
Does [11C]mHED-PET imaging reveal differences in cardiac presynaptic norepinephrine recycling in patients with long-QT syndrome compared to healthy controls?
[11C]mHED-PET imaging reveals increased regional washout rates in the lateral left ventricle of LQTS patients, suggesting a presynaptic sympathetic imbalance that may serve as a non-invasive risk marker.
Answers are grounded in this paper and cite their sources.
May indicate presynaptic sympathetic imbalance in LQTS; hypothesis-generating for non-invasive risk stratification.
Objective We investigated the impact of cardiac presynaptic norepinephrine recycling in patients with long-QT syndrome (LQTS) using positron emission tomography (PET) with 11 C-meta-hydroxyephedrine ([ 11 C]mHED-PET). Methods [ 11 C]mHED-PET was performed in 25 patients with LQTS (LQT1: n=14; LQT2: n=11) and 20 healthy controls and correlated with clinical parameters. [ 11 C]mHED-PET images were analysed for global and regional retention indices (RI) and washout rates (WO) reflecting dynamic parameters of the tracer activity. Results Global and regional RI values were similar between patients with LQTS and controls. Although the global WO rates were similar between these groups, regional WO rates were on average higher in the lateral left ventricle (LV) wall in patients with LQTS (dose, mean ±SD; 0.08±0.14 vs 0.00%±0.09% min –1 ; p=0.033). In addition, patients with LQTS with a longer QTc interval showed a higher global WO rate. Clinical symptoms correlated with higher global WO rates. In the presence of normal global WO rates, asymptomatic LQTS patients showed higher global RI values. Conclusion The increased regional WO rate of [ 11 C]mHED in the lateral LV suggests an imbalance of presynaptic catecholamine reuptake and release, resulting in a higher synaptic catecholamine concentration, in particular in LQT1 patients. This might enhance β-adrenoceptor signalling and thereby aggravate inherited ion channel dysfunction and may facilitate occurrence of ventricular tachyarrhythmias. Detection of regional differences in LV sympathetic nervous function may modify disease expression and potentially serve as a non-invasive risk marker in congenital LQTS. Trial registration number 2006-002767-41;Results.
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Zumhagen et al. (2017) conducted a case-control in Long-QT syndrome (LQTS) (n=45). [11C]mHED-PET imaging vs. Healthy controls was evaluated on Regional washout rates in the lateral left ventricle wall (p=0.033). Patients with long-QT syndrome exhibited higher regional washout rates of [11C]mHED in the lateral left ventricle wall compared to healthy controls.
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