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| The Significance of Cardiac Sympathetic Nerve Imaging with 123I-metaiodobenzylguanidine for Predicting Ventricular Tachycardia in Patients with Idiopathic Dilated Cardiomyopathy |
| Cardiovascular Division and Nuclear medicine*, Yeungnam Univ. Hospital, Daegu, South Korea |
| DH Kim, DG Shin, IH Cho*, HJ Kim, JH Bae, GR Hong, JS Park, YJ Kim, BS Shim |
Background and Objectives: Ventricular arrhythmia is an important cause of death in idiopathic dilated cardiomyopathy(IDCM). Decreased uptake or increased "washout" of 123I-metaiodobenzylguanidine(MIBG)-derived radioactivity is associated with worse prognosis or more severe disease in cardiac diseases. This study is designed to assess the relation between cardiac MIBG uptake and occurrence of ventricular tachycardia(VT) in patients with IDCM.
Methods and Results: Nineteen patients(12 men, mean age 56.8±11.6 years) with angiographically proved IDCM were studied and divided into 2 groups with clinically documented VT(group A; 5 patients ) and without VT( group B: 14 patients). Echocardiography, myocardial dual SPECT imaging with MIBI and MIBG were performed in all patients. 123I MIBG was evaluated by early(15min) and delayed(3hours) uptake, heart to mediastinum uptake(H/M) ratio, global and regional washout ratio(WOR) defined as [early H/M ratio-delayed H/M ratio]/early H/M ratio×100. We also quantified the presence of MIBI/MIBG mismatched regions. The clinical variables, echocardiographic parameters and 123I MIBG-derived parameters were compared between the 2 groups.
Results: There were no significant difference in age, LVEF(26.6±15.5% versus 25.6±8.5%), LVESD and LVEDD between the 2 groups. A significant negative correlation was present between early H/M ratio and LVEDD( Pearson correlation, r=-0.558, P=0.013), early H/M ratio and LVESD.( r=-0.545, P=0.016) Delayed H/M ratio also showed a significant negative correlation with LVEDD (r= -0.483, P = 0.036) and LVESD (r=-0.448, P=0.054). Group A patients had lower early or delayed H/M ratio and higher general WOR than group B, although statistically not significant. The regional WOR at inferior wall and septum showed a tendency to be higher in group A.(10.2±11.5 versus 3.2±5.5; P=0.085 and 12.9±14.0 versus 4.3±6.7; P=0.082, respectively) than group B.
Conclusion: Cardiac 123I-MIBG scan partially reflect the vulnerability to VT occurrence in IDCM. These results support the feasibility of cardiac 123I-MIBG scan as a prognostic tool in IDCM patients.
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