Prognostic significance of (123)I-mIBG SPECT myocardial imaging in heart failure: differences between patients with ischaemic and non-ischaemic heart failure.

AIMS: The purpose of this study was to examine the prognostic significance of uptake patterns on quantitative myocardial (123)I-mIBG and (99m)Tc-tetrofosmin SPECT imaging in heart failure (HF) subjects and to assess the differences between patients with ischaemic and non-ischaemic HF.

METHODS AND RESULTS: Results of quantitative analyses of (123)I-mIBG myocardial SPECT, alone and in combination with (99m)Tc tetrofosmin SPECT, were studied in 619 ischaemic (I) and 319 non-ischaemic (NI) HF subjects from the ADMIRE-HF trial. Cardiac and all-cause mortality data for 2-year follow-up were collected in the extension study (ADMIRE-HFX) and were examined in relation to extent and severity of voxel-based defects, the number of myocardial segments with significant dysinnervation (derived score ≥2), and (123)I-mIBG/(99m)Tc tetrofosmin mismatch quantitation. Cox proportional hazards and survival analyses were used to identify higher and lower risk groups and to define thresholds for optimal discrimination between the two. Two-year all-cause and cardiac mortality were not significantly different between IHF and NIHF subjects. Mortality was higher in patients with dysinnervation involving >50% of the myocardium. Highest cardiac mortality risk for IHF subjects was seen with perfusion defects involving 20-40% of the myocardium. By comparison, NIHF subjects with smaller perfusion abnormalities (<20% of myocardium), but with a large discrepancy between (123)I-mIBG and (99m)Tc tetrofosmin defect sizes, were at highest risk of cardiac death.

CONCLUSIONS: Prognostic significance of patterns of (123)I-mIBG and MPI uptake differ between IHF and NIHF subjects. SPECT imaging may provide new insights into underlying disease processes in HF, including the degree of dysinnervation in areas with preserved myocardial perfusion in non-ischaemic HF patients.