Cardiac I-123-mIBG scintigraphy is associated with freedom of appropriate ICD therapy in stable chronic heart failure patients

Aim: Chronic heart failure (CHF) is a life-threatening clinical syndrome, partly due to sudden cardiac death (SCD). Implantable cardioverter defibrillators (ICD) for primary prevention of SCD have improved overall survival of CHF patients. However, a high percentage of patients never receives appropriate ICD therapy. This prospective multicentre study evaluated whether cardiac sympathetic activity assessed by I-123-mIBG scintigraphy could be helpful in selecting patients for ICD implantation. Materials and methods: 135 stable CHF subjects (age 64.5 +/- 9.3 years, 79% male, LVEF 25 +/- 6%) referred for prophylactic ICD implantation were enrolled in 13 institutions. All subjects underwent planar and SPECT I-123-mIBG scintigraphy. Early and late heart-to-mediastinum (H/M) ratio, I-123-mIBG washout (WO) and late summed scores were calculated. The primary endpoint was appropriate ICD therapy. The secondary endpoint was defined as the combined endpoint of all first cardiac events: appropriate ICD therapy, progression of heart failure (HF) and cardiac death. Results: During a median follow-up of 30 months (6-68 months), 24 subjects (17.8%) experienced a first cardiac event (appropriate ICD therapy [12], HF progression [6], cardiac death [6]). Late H/M ratio and defect size of I-123-mIBG SPECT were not associated with appropriate ICD therapy. However, late H/M ratio was independently associated with the combined endpoint (HR 0.135 [0.035-0.517], p = 0.001). Post-hoc analysis showed that the combination of late H/M ratio (HR 0.461 [0.281-0.757]) and LVEF (HR 1.052 [1.021-1.084]) was significantly associated with freedom of appropriate ICD therapy (p <0.001). Conclusion: I-123-mIBG scintigraphy seems to be helpful in selecting CHF subjects who might not benefit fromICD implantation. (C) 2017 Elsevier B.V. All rights reserved