A wall based regional innervation/perfusion mismatch assessed by cardiac 123I-mIBG and rest 99mTc-tetrofosmin SPECT to predict arrhythmic events in ischemic heart failure patients

Abstract

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Cardiac 123I-mIBG SPECT imaging provides information on regional myocardial innervation. However, there is no consensus on how to use a, 17-segment based score to assess prognosis. The present study examined whether a simpler regional scoring approach for evaluation of 123I-mIBG SPECT combined with rest 99mTc-tetrofosmin SPECT myocardial perfusion imaging could be used for the prediction of arrhythmic events (AEs) in ischemic heart failure (HF). Methods 261 ischemic HF subjects (NYHA II/III, LVEF ≤35% on gated SPECT) of the ADMIRE-HF study cohort with complete cardiac 123I-mIBG and rest 99mTc-tetrofosmin SPECT studies were enrolled. Both SPECT image sets were read together by 2 experienced nuclear imagers and scored by consensus. In addition to standard 17 segments scoring, the readers classified walls (i.e. anterior, lateral, inferior, septum and apex) as normal, matched defect of innervation and perfusion, mismatched (i.e., innervation defect lager than perfusion defect) or reverse mismatched (i.e., innervation defect smaller than perfusion defect). Cox proportional hazards ratios (HR) were used to determine if the visual segmental wall classification innervation/perfusion mismatch score, 123I-mIBG summed defect scores (SDS), 99mTc-tetrofosmin SDS and innervation/perfusion mismatch SDS, age, LVEF, NYHA class, B-type natriuretic peptide (BNP) and norepinephrine (NE) plasma levels were associated with occurrence of AEs (i.e. sudden cardiac death, sustained VT, resuscitated cardiac arrest, appropriate ICD therapy). Results At 2-year median follow-up, 38 subjects (14.6%) had AEs. Subjects with 1 or 2 mismatched walls were more than twice as likely to have AEs compared with subjects with either 0 or 3-5 mismatched walls (24.0% vs 10.8%, p = 0.006). Cox regression analyses showed that the combination of the presence of visual mismatch in 1-2 walls and BNP and were the only independent predictors of AEs (HR 2.583 [1.261-5.107],p = 0.001) However, compared to the visual mismatch, the contribution of BNP is relatively small (i.e., HR 1.001 [1.000-1.001]). Conclusion In ischemic HF with LVEF ≤35 the highest risk of AEs occurs in subjects with intermediate levels of visual wall-level innervation/perfusion mismatches. Therefore, a simple visual wall-level based assessment of combined cardiac 123I-mIBG and rest 99mTc-tetrofosmin SPECT can be used to differentiate those HF patients at higher AE risk from those with relatively low AE risk. Table 1. Cox regression analysis Variable HR (95% CI) X2 change X2 p-value AE’s 1-2 mismatched segments 2.412 (1.204-4.830) 6.581 5.880 0.010 BNP 1-2 mismatched segments 1.001 (1.000-1.001) 2.538 (1.261-5.107) 13.434 4.129 0.001 Abstract Figure. Kaplan Meier curves for AEs