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

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- m IBG) scintigraphy as a predictor of arrhythmic events (AE) in CHF patients. 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- m IBG 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. 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- m IBG-derived parameters failed to be independent predictors of appropriate ICD therapy. However there was a “bell-shaped” relation between 123 I- m IBG scintigraphy-derived parameters and AE and appropriate ICD therapy, i.e., those with intermediate 123 I- m IBG abnormalities tended to be at higher risk of events. Although SPECT 123 I- m IBG scintigraphy was associated with AE in CHF patients with ICD implantation for primary and secondary prevention, no association was found between 123 I- m IBG scintigraphy-derived parameters and appropriate ICD therapy.