176-01: Radiofrequency cardiac denervation: scintigraphic evaluation of the effectiveness

Abstract

Purpose: The aim of the study was to evaluate the role of radionuclide imaging with 123I-metaiodbenzilguanidine (123I-MIBG) in assessing of the cardiac radiofrequency denervation effectiveness. Methods and Materials: In this study were enrolled 32 patients with mitral valve (MV) disease: 21 patients with long-standing persistent atrial fibrillation, who was undergone MV surgery and the «Maze» procedure (Maze+ group) and 11 patients with sinus rhythm and with MV surgery without the «Maze» procedure (Maze- group). All patients underwent cardiac 123I-MIBG imaging prior and 10 days after surgery. The early and delayed heart-to-mediastinum ratio (HMR) and the washout rate (WR) were performed. Local denervation was evaluated on polar map images using the 17-segment model of left ventricle (LV). In addition, we determined the levels of norepinephrine, metanephrine, normetanephrine in plasma, obtained intraoperatively from the coronary sinus (CS) and the ascending aorta (Ao) before and after the main stage of the surgery. All patients were intraoperatively intake of histological material (left atrial appendage) to determine the distribution density of nerve endings in the myocardium. Results: In patients with AF the early HMR and delayed HMR prior surgery were significantly lower compared to patients with SR (p < 0.01). The washout rate of 123I-MIBG prior surgery in patients with AF was greater compared to patients with SR (p < 0.01). The HMR after surgery was significantly lower vs baseline in both groups (early HMR: 1,78 ± 0,17 vs 1,56 ± 0,19; p < 0,01 and 2,12 ± 0,25 vs 1,79 ± 0,18; p < 0,01; delayed HMR: 1,69 ± 0,21 vs 1,47 ± 0,19; p < 0,01 and 2,0 ± 0,22 vs 1,74 ± 0,19; p < 0,01). The WR after surgery was significantly increased vs baseline in both groups (27,3% ± 14,03% vs 35,0% ± 14,18%; p < 0,01 and 17,1% ± 13,7% vs 31% ± 16,15%; p < 0,01). After surgery sympathetic activity defect was increased only in the Maze+ group (12,7% ± 7,3% and 25,4% ± 8,5%; p < 0,01). The correlations between the cardiac 123I-MIBG parameters and the levels of norepinephrine, metanephrine, normetanephrine in plasma were examined. Cardiac 123I-MIBG parameters had significant correlations with transcardiac gradients (CS-Ao) of the norepinephrine and normetanephrine. Cardiac 123I-MIBG parameters had significant correlations with the distribution density of nerve endings in the myocardium. Conclusion: Results of this study indicated that the more sympathetic innervation abnormality prior surgery was observed in patients with AF. In patients who had undergone MV surgery without the «Maze» procedure, there were no significant changes in sympathetic activity defect in the early stage. The MV surgery itself doesn't influence the regional cardiac sympathetic activity. The evaluation of the cardiac nervous activity using 123I-MIBG scintigraphy may be a promising tool to determine of effectiveness of the cardiac radiofrequency denervation. The study was supported by a grant from the Russian Science Foundation № 15-15-10016.