Role of cardiac (123)I-mIBG imaging in predicting arrhythmic events in stable chronic heart failure patients with an ICD

BACKGROUND: Despite therapeutic improvement, the prognosis of chronic heart failure (CHF) remains unfavorable partly due to arrhythmia and sudden cardiac death (SCD). This prospective study evaluated myocardial (123)I-meta-iodobenzylguanidine ((123)I-mIBG) scintigraphy as a predictor of arrhythmic events (AE) in CHF patients. METHODS: 170 CHF patients referred for implantable cardioverter-defibrillator (ICD) implantation for both primary and secondary prevention were enrolled. All patients underwent planar and SPECT imaging. Early and late heart-to-mediastinum (H/M) ratio, (123)I-mIBG washout (WO), early and late summed SPECT scores were calculated The primary endpoint was an AE: sustained ventricular tachycardia, resuscitated cardiac arrest, appropriate ICD therapy or SCD. The secondary endpoint was appropriate ICD therapy. RESULTS: During a median follow-up of 23.3 months, 69 patients experienced an AE. Early summed score (ESS) was the only independent predictor of AE [HR 1.023 (1.003-1.043)]. Focussing on only patients with an ICD for primary prevention, ESS was the only independent predictor of AE [HR 1.028 (1.007-1.050)]. (123)I-mIBG-derived parameters failed to be independent predictors of appropriate ICD therapy. However there was a “bell-shaped” relation between (123)I-mIBG scintigraphy-derived parameters and AE and appropriate ICD therapy, i.e., those with intermediate (123)I-mIBG abnormalities tended to be at higher risk of events. CONCLUSION: Although SPECT (123)I-mIBG scintigraphy was associated with AE in CHF patients with ICD implantation for primary and secondary prevention, no association was found between (123)I-mIBG scintigraphy-derived parameters and appropriate ICD therapy. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1007/s12350-018-1258-z) contains supplementary material, which is available to authorized users.