Close Association of Matrix Metalloproteinase-9 Levels With the Presence of Thin-Cap Fibroatheroma in Acute Coronary Syndrome Patients: Assessment by Optical Coherence Tomography and Intravascular Ultrasonography

BackgroundThin-cap fibroatheroma (TCFA) has been suggested as a precursor lesion of coronary plaque rupture. As elevated plasma matrix metalloproteinase-9 (MMP-9) levels have been documented in patients with acute coronary syndrome (ACS), we sought to determine whether the presence of TCFA is linked to MMP-9 levels in these patients.MethodsWe evaluated 51 ACS patients with de novo culprit lesions who were examined via optical coherence tomography and intravascular ultrasound. Blood samples were obtained from the peripheral vein (PV) and the ostium and culprit lesion of the infarct-related coronary artery (CA) in the acute phase of ACS and from the PV in the chronic phase (8 months after ACS).ResultsThe plasma MMP-9 level in the acute phase was significantly higher than that in the chronic phase. Plasma MMP-9 levels at the culprit lesion of the infarct-related CA were significantly higher than, but positively correlated with those in the PV (10.9 (5.9–16.1) ng/mL and 8.9 (5.6–13.0) ng/mL, p < 0.0001, respectively; Spearman ρ = 0.84, p < 0.0001). Significantly higher PV plasma MMP-9 levels were observed in patients with TCFA than in patients without TCFA (12.1 (7.0–13.5) and 5.7 (4.0–8.2) ng/ml, p<0.0001, respectively). Further, plasma MMP-9 levels in the PV were positively correlated with the remodeling index (Spearman ρ = 0.29, p = 0.039) and negatively correlated with fibrous cap thickness (Spearman ρ = −0.42, p = 0.0021). Receiver operating characteristic curve analysis showed that the plasma MMP-9 levels in the PV could predict the presence of TCFA at a cut-off value of 9.9 ng/mL.ConclusionsPlasma MMP-9 levels were closely associated with MMP-9 levels in the CA and were further linked with TCFA in patients with ACS.