Abstract 2749: Utility of I-123-MIBG Scintigraphy in Subjects with Heart Failure for Assessment of Risk for a Major Cardiac Event: A European Multi-center Study
Function of myocardial sympathetic neurons plays a central role in the successful treatment of heart failure (HF). 123I-mIBG scans performed at multiple centres in Europe were prospectively reanalyzed to verify the prognostic value of this method for assessing myocardial sympathetic innervation in HF.
Methods 290 HF patients (237 M, 53 F; 53+/-11 yrs; NYHA Class: II:165, III:116, IV:9; 169 dilated, 121 ischaemic cardiomyopathy; mean LVEF: 32+/-14%) imaged from 1994–2002 at 6 European centres were included. HF treatment: ACE-Inhibitors/ARBs (89%); Beta Blockers (73%); Aldosterone-Inhibitors (42%). Blinded readers analyzed delayed (3–5 hour) planar 123I-mIBG images for heart-to-mediastinum ratio (H/M). Major cardiac events (MCE) (cardiac death; cardiac transplant; potentially fatal arrhythmia (including ICD discharge)) during 24-month follow-up were confirmed by an adjudication committee. ROC and Kaplan-Meier curves were used in the analyses of H/M and MCE event risk.
Results MCEs occurred in 67 pts (23%): 18 deaths (5 SCD), 44 transplants, 5 arrhythmic events. Mean H/M: 1.51+/-0.3 for MCE group, 1.97+/-0.54 for non-MCE group (p<0.001). Optimum H/M threshold for MCE prediction per ROC curves was 1.75; sensitivity: 84%, specificity: 60%; odds ratio: 7.6 (p<0.0001). Two-year event-free survival was 62% for H/M<1.75, 92% for H/M≥1.75 (p<0.00001). Using H/M of 1.4 and 2.0 as high and low risk thresholds, two-year event-free survival was 45% for H/M<1.4, 95% for H/M≥2.0 (p<0.000001). Of patients with LVEF≤35% (n=191), the 39 (20%) with low-risk H/M had 3 MCEs, all due to HF progression (1 death, 2 transplants), none to arrhythmias. Logistic regression showed H/M (p<0.0001) and LVEF (p<0.001) as significant MCE predictors.
Conclusion 123I -mIBG imaging to assess cardiac sympathetic innervation has powerful prognostic value in HF patients. The data suggest that a quantitative threshold for low-risk for potentially fatal ventricular arrhythmias can be defined.