P6329123-Iodine Metaiodobenzylguanitidine imaging: a useful prognostic marker of cardiovascular death in heart failure patients
Abstract Background According to guidelines, implantable cardioverter defibrillator (ICD) is recommended in prevention of sudden cardiac death (SCD) in heart failure (HF) patients (pts). Guidelines have several limitations because ICD indication is based mainly on left ventricular ejection fraction (LVEF). Recently, 123-iodine metaiodobenzylguanidine imaging (123-I MIBG) seems to identify, independently from LVEF, pts at high risk of SCD: heart/mediastinum (H/M) ratio<1.6 and summed score (SS)>26. Purpose The aim is to assess the role of 123-I MIBG to predict malignant ventricular arrhythmias (VA) in HF pts Methods We enrolled 208 pts, admitted to our hospital with diagnosis of HF and LVEF≤35%, NYHA class II and III, who underwent 123-I MIBG imaging. H/M ratio of 1.6 was used as a cut-off to identify high risk (G1) versus low risk pts (G2). All pts underwent ICD implantation. Follow-up was performed at 24 months. Results 138 patients were included in G1 and 70 patients in G2. All baseline characteristics were similar in the two groups (table 1). At 24 months follow-up VA events were recorded greater in G1 compared to G2 (21% vs 10%, p=0.04). Table 1 G1 G2 P value H/M ≤1.6 (N=138) H/M >1.6 (N=70) Age (years) 65±12 63±14 0.28 Male, N (%) 108 (78) 64 (91) 0.02 Diabetes mellitus type II, N (%) 54 (39) 14 (20) 0.01 Dyslipidemia, N (%) 58 (42) 30 (42) 0.64 LVEF (%) 30±5 31±4 0.14 Ischaemic CM, N (%) 85 (62) 30 (42) 0.012 Malignant VA, N (%) 30 (21) 7 (10) 0.04 SS 38±9 16±7 0.0001 H/M: heart mediastinum ratio; LVEF: left ventricular ejection fraction; CM: cardiomyopathy; VA: ventricular arrhythmias; SS: summed score. Conclusion Our results seem to confirm that 123-I MIBG uptake is associated with the occurrence of life-threatening VA in HF pts independently from LVEF. The use of 123-I MIBG could be a useful tool in the future to increase the specificity of the pts selection for ICD therapy.