Heterogeneity of Ventricular Sympathetic Nervous Activity is Associated with Clinically Relevant Ventricular Arrhythmia in Postoperative Patients with Tetralogy of Fallot

Abstract

This study aimed to clarify whether there is an association between ventricular sympathetic nervous activity (SNA) and clinically relevant ventricular arrhythmia (a run of ≥ 3 consecutive ventricular beats, RVA) in postoperative patients with tetralogy of Fallot (TOF). We performed a retrospective study in a national referral center of pediatric cardiology in Japan. Twenty-four postoperative TOF patients (13 males, median age 17 years) undergoing myocardial (123)I metaiodobenzylguanidine (MIBG) scintigraphy were included. We measured the heart-to-mediastinum ratio (HMR) and washout ratio (WR) from planar MIBG myocardial scintigraphy. Tomographic images and polar maps were generated with 20 segments. The standard deviation of percentage uptake of 20 segments (SD-uptake) as an index of heterogeneous MIBG uptake to the ventricular myocardium was calculated. We compared these MIBG-derived variables with the patients' clinical profiles, including ECG findings and hemodynamics. Eight of 24 patients had RVA (RVA group), and the other 16 did not have RVA (non-RVA group). There were no significant differences in the HMR (1.9 ± 0.5 vs. 2.2 ± 0.4) and WR (50 ± 5 vs. 42 ± 10) between the two groups. SD-uptake was significantly higher in the RVA group than in the non-RVA group (15 ± 3 vs. 12 ± 3, p = 0.03). QT dispersion (ms) was also higher in the RVA group than in the non-RVA group (53 ± 23 vs. 44 ± 18, p = 0.04). Multivariate logistic regression showed that SD-uptake and QT dispersion were independent predictors in the RVA group (p = 0.02, p = 0.03). In addition to greater QT dispersion, heterogeneous SNA is associated with RVA in TOF patients postoperatively.

Myocardial Functional Imaging in Pediatric Nuclear Cardiology

“…123 I-MIBG scintigraphy and [ 11 C] mHED PET are used for the evaluation of cardiac sympathetic innervation. Their utilization in children for this purpose is well-documented [ 67 , 69 , 70 ].…”

Nuclear Imaging in Pediatric Cardiology: Principles and Applications

“…Interestingly, in ischemic cardiomyopathies, autonomic imaging may better predict life-threatening ventricular arrythmias than parameters as LVEF ( 132 ). Some teams have also shown that the heterogeneity of meta-iodobenzylguanidine (MIBG) uptake was correlated with risk of arrhythmia in patients with tetralogy of Fallot ( 134 ) or in congenital long QT syndrome ( 135 ). In another hand, Possner et al have shown that the incomplete cardiac reinnervation late after the arterial switch operation for TGA can at least partially explain the reduced myocardial perfusion response to sympathetic pharmacological stimulation in these patients ( 130 ).…”