Abstract Body (Do not enter title and authors here): Background
Hemodialysis (HD) is a cause of arteriosclerosis, and approximately half of the deaths are due to cardiovascular disease. Myocardial flow reserve (MFR) derived from ¹³N-ammonia positron emission tomography (NH₃-PET) is a prognostic factor for patients with ischemic heart disease. In NH₃-PET imaging, the splenic switch-off (SSO) sign, which demonstrates the decrease in splenic ¹³N-ammonia uptake during adenosine stress, is a hemodynamic indicator of a favorable response to adenosine. This phenomenon is owing to the fact that adenosine receptor stimulation produces coronary artery dilation while producing vasoconstriction in the splenic circulation. Previous study indicated SSO was a predictor of coronary artery event in patients with heart transplantation.
Hypothesis
We hypothesized that patients with HD had arteriosclerosis of the systemic blood vessels, and splenic reactivity to adenosine was reduced. Therefore, the aim of this study was to compare the splenic blood flow assessed by NH₃-PET among patients with HD, non-HD and renal transplantation, and examine its prognostic value for major adverse cardiac event (MACE).
Methods
100 patients (HD: 40, non-HD: 50, renal transplantation: 10) who underwent NH₃-PET were enrolled. Using NH₃-PET projection images, we placed an ROI on the spleen and measured the mean standardized uptake value (SUV). The spleen ratio (SR) was defined as the mean SUV of the spleen at stress divided by that at rest, and compared among the three groups using the Kruskal–Wallis test. The endpoint was the occurrence of MACEs comprising acute coronary syndrome, heart failure hospitalization, and all-cause mortality. SSO was determined by a cutoff obtained using receiver operating characteristic (ROC) analysis for the SR. The patients were divided into two groups according to the presence or absence of SSO, and the frequency of MACE was compared by Kaplan-Meier and log-rank test.
Results
Patients with HD had reduced MFR (1.7±0.6 vs. 2.1±0.6, p=0.0057). The SR was significantly higher in the HD group than the non-HD group (0.92±0.16 vs. 0.78±0.21, p=0.014). The ROC curve analysis of the SR for MACE demonstrated a cutoff value of 0.96. Patients without SSO had higher rate of MACE than with SSO (p=0.0074).
Conclusions
Splenic blood flow reactivity to adenosine in patients with HD was reduced compared to those with non-HD. SSO might be related with the endothelial function of systemic blood vessels and was a prognostic factor for MACE.