I-123-mIBG myocardial imaging for assessment of risk for a major cardiac event in heart failure patients: insights from a retrospective European multicenter study
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Single-center experiences have shown that myocardial meta-iodobenzylguanidine (mIBG) uptake has prognostic value in heart failure (HF) patients. To verify these observations using a rigorous clinical trial methodology, a retrospective review and prospective quantitative reanalysis was performed on a series of cardiac 123I-mIBG scans acquired during a 10-year period at six centers in Europe.
123I-mIBG scans obtained on 290 HF patients [(262 with left ventricular ejection fraction (LVEF) < 50%)] from 1993 to 2002 were reanalyzed using a standardized methodology to determine the heart-to-mediastinum ratio (H/M) on delayed planar images. All image results were verified by three independent reviewers. Major cardiac events [MCEs; cardiac death, cardiac transplant, potentially fatal arrhythmia (including implantable cardioverter-defibrillator discharge)] during 24-month follow-up were confirmed by an adjudication committee.
MCEs occurred in 67 patients (26%): mean H/M ratio was 1.51 ± 0.30 for the MCE group and 1.97 ± 0.54 for the non-MCE group (p < 0.001). Two-year event-free survival using an optimum H/M ratio threshold of 1.75 was 62% for H/M ratio less than 1.75, 95% for H/M ratio greater than or equal to 1.75 (p < 0.0001). Logistic regression showed H/M ratio and LVEF as the only significant predictors of MCE. Using the lower and upper H/M quartiles of 1.45 and 2.17 as high- and very low-risk thresholds, 2-year event-free survival rates were 52% and 98%, respectively. Among patients with LVEF ≤ 35% and H/M ≥ 1.75 (n = 73), there were nine MCEs because of progressive HF and only one because of an arrhythmia.
Application of a clinical trial methodology via the retrospective reanalysis of 123I-mIBG images confirms the previously reported prognostic value of this method in HF patients, including potential identification of a quantitative threshold for low risk for cardiac mortality and potentially fatal ventricular arrhythmias.
KeywordsCardiology mIBG Scintigraphy Nuclear imaging Prognosis
This study was funded by GE Healthcare. Denis Agostini and Wolfgang Burchert are principal investigators in an ongoing multicenter clinical trial employing 123I-mIBG sponsored by GE Healthcare. Gopa Banerjee and Arnold Jacobson are employed by GE Healthcare. The participation of Hospitalier Frederic Joliot, CEA, Orsay, France, in this study is gratefully acknowledged. All activities performed in this study comply with the current laws of the countries in which it was performed, inclusive of ethics approval.
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