Interpretative variability and its impact on the prognostic value of myocardial fatty acid imaging in asymptomatic hemodialysis patients in a multicenter trial in Japan.

ABSTRACT

BACKGROUND: The severity of impaired fatty acid utilization in the myocardium can predict cardiac death in asymptomatic patients on hemodialysis. However, interpretive variability and its impact on the prognostic value of myocardial fatty acid imaging are unknown. METHODS AND RESULTS: A total of 677 patients who received hemodialysis for ≥ 20 years and had one or more cardiovascular risk factors underwent (123)I-labeled ß-methyl iodophenyl-pentadecanoic acid (BMIPP) single-photon emission computed tomography (SPECT) at 48 hospitals across Japan. SPECT images were interpreted by experts at the nuclear core laboratory and by readers with varying skill levels at clinical centers, based on the standard 17-segment model and 5-point scoring systems, independently. The κ values only reached fair agreement both for overall impression (κ=0.298, normal vs. abnormal) and for categorical impression (κ=0.244, normal vs. mildly abnormal vs. severely abnormal). The normalcy rate was lower in readers at the clinical centers (60.9%) than in experts (69.9%). In contrast to the results assessed by experts, a Kaplan-Meier analysis based on the interpretation by readers at the clinical centers failed to distinguish the risk of events in patients with normal scans from that of patients with mildly abnormal scans. CONCLUSIONS: Considerable variability and its impact on prognostic value were observed in the visual interpretation of BMIPP SPECT images between experts and readers at the clinical centers.