Significance of soluble lectin-like oxidized LDL receptor-1 levels in systemic and coronary circulation in acute coronary syndrome.

Background. Soluble lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) level is a novel biomarker for diagnosis of acute coronary syndrome (ACS); however, this level in the coronary circulation has yet to be examined. Methods. Twenty-seven consecutive patients with ACS and 40 patients with effort angina pectoris (EAP) undergoing percutaneous coronary intervention (PCI) had levels of soluble LOX-1 and LOX-1 index measured in paired blood samples from aorta (Ao) and coronary sinus (CS) just prior to the PCI. Results. We found positive correlations between soluble LOX-1 levels in the Ao and CS in both ACS and EAP patients (P < 0.01, for both). The soluble LOX-1 levels in the Ao and CS were higher in ACS than in EAP patients (P < 0.01, for both). The levels of soluble LOX-1 and LOX-1 index of the CS were significantly greater than those of the Ao in both ACS and EAP patients (P < 0.01, for both). Receiver operating characteristic curves for ACS detection demonstrated high sensitivity and specificity for the soluble LOX-1 and LOX-1 index with no differences between the Ao and CS. Conclusions. The present study showed that circulating soluble LOX-1 originates from coronary circulation and soluble LOX-1 and LOX-1 index are useful biomarkers for ACS.