Purpose: Iodine-123 meta-iodobenzylguanidine (I-mIBG) imaging has prognostic value in patients with heart failure (HF). Renal dysfunction is prevalent in HF patients. I-mIBG is excreted by the kidneys, and the effect of renal dysfunction on its myocardial uptake and established prognostic value in HF patients is unknown.
Materials and methods: The data analysed are from patients with New York Heart Association (NYHA) class II or III HF enrolled in the AdreView Myocardial Imaging for Risk Evaluation in Heart Failure (ADMIRE-HF) study. Myocardial uptake and retention of I-mIBG were assessed by the early and late heart-to-mediastinal (HM) ratio. Effect of renal dysfunction on the prognostic value of I-mIBG was determined by multivariable-predicted survival analysis stratified by glomerular filtration rate (GFR) and late HM ratio. Cox proportional hazard models were used to determine the predictors of cardiac events (CEs, defined as death, HF progression or life-threatening arrhythmia).
Results: Complete data were available on 867 patients. The GFR range was 19-140 ml/min, and 344 (40%) patients had renal dysfunction (GFR<60 ml/min). A total of 523 (60%) and 689 (80%) patients had early and late HM ratios below the previously established prognostic cutoff of 1.6. There was no relationship between early or late HM ratios and GFR after controlling for HF severity (NYHA class and norepinephrine levels), indicating a lack of effect of renal dysfunction on the HM ratio. Significant independent predictors of CE were (hazard ratio, P), b-type natriuretic peptide level (1.4, <0.001), left ventricular ejection fraction (0.95, <0.001), BMI (1.04, 0.002), cardiac glycoside use (1.42, 0.019) and late HM ratio (7.04, 0.008). Neither GFR nor its interaction with late HM ratio was a significant predictor of CE.
Conclusion: Renal dysfunction does not affect the HM ratios or the prognostic value of I-mIBG imaging in HF patients.