Effect of B-Blocker Therapy for T-Wave Alternans and Cardiac Sympathetic Function in Patients With Nonischemic Heart Disease

Presentation Time: Monday, 10:00 a.m. - 11:00 a.m.

Mariko Murata, Masahiko Harada, Akihiko Shimizu, Makoto Kubo, Reo Mitani, Yuka Dairaku, Masunori Matsuzaki, The Second Department of Internal Medicine, Yamaguchi University School of Medicine, Ube, Japan, The Faculty of Health Science, Yamaguchi University School of Medicine, Ube, Japan.

Presentation Number: 1093-110

Poster Board Number: 110

Keyword: Ventricular arrhythmia, Beta-adrenergic receptor blockers, Autonomic nervous system, Ejection fraction

Background: We have reported that cardiac sympathetic denervation was related to the presence of T-wave alternans (TWA) in patients with non-ischemic heart disease (NIHD) in the previous ACC meeting. Recently, it has been observed that mechanical alternans disappeared with the improvement of left ventricular ejection fraction (EF) with ß-blocker therapy in patients with DCM. The aim of this study was to investigate whether TWA findings also improve together with the improvement of cardiac sympathetic denervation and EF with ß-blocker in positive TWA patients with NIHD.
Methods: Eighteen positive TWA patients with NIHD not treated with ß-blockers were enrolled. The TWA test, I-123 metaiodobenzylguanidine (MIBG) scintigraphy, and echocardiography were performed at baseline and after 3 months of treatment with ß-blockers. Using alternans voltage of the vector magnitude (Valt) in the TWA test, the decrease rate of Valt (% Valt) was calculated {% Valt=(pre Valt- post Valt)/pre Valt *100; pre: before administration, post: after administration}. The heart/mediastinal count ratios in the early phase (eH/M) and delayed phase (dH/M), and the washout rate (WR) were calculated using MIBG scintigraphy, and EF was measured with echocardiography. The rate of change between baseline and after administration was calculated using the following formula {% eH/M=(post eH/M- pre eH/M)/pre eH/M *100, % dH/M=(post dH/M- pre dH/M)/pre dH/M *100, % WR=(post WR- pre WR)/pre WR *100, % EF=(post EF- pre EF)/pre EF *100}. Simple regression analysis was performed to examine the relationship between each parameter obtained from MIBG or echocardiography and % Valt.
Results: Significant negative correlations were recognized between pre eH/M, pre dH/M or pre EF and % Valt (eH/M: R =0.62, p < 0.01, dH/M: R =0.62, p <0.01, EF: R=0.52, p<0.05). Significant positive correlations were also seen between % eH/M, % dH/M or % EF and % Valt (% eH/M: R =0.57, p < 0.05, % dH/M: R =0.68, p < 0.01, % EF: R =0.50, p < 0.05).
Conclusion: TWA findings improved together with the improvement of cardiac sympathetic denervation and EF with ß-blocker therapy in positive TWA patients with denervation and systolic dysfunction.