High levels of systemic myeloperoxidase are associated with coronary plaque erosion in patients with acute coronary syndromes: a clinicopathological study.

BACKGROUND: Systemic levels of myeloperoxidase predict prognosis in patients with acute coronary syndromes and are considered a marker of plaque vulnerability. It is not known whether myeloperoxidase is associated with different coronary morphologies (ie, rupture or erosion of the culprit lesion) in patients with acute coronary syndrome.

METHODS AND RESULTS: Twenty-five consecutive patients (aged 67±11 years; 15 men [60%]; 13 [52%] with non-ST-segment elevation acute coronary syndrome and 12 [48%] with acute ST-segment elevation myocardial infarction) were enrolled. Optical coherence tomography classified the culprit lesion as ruptured in 18 (72%) or eroded in 7 patients (28%) and detected intraluminal thrombus in 89% of ruptured plaques and 100% of eroded plaques. Baseline systemic levels of serum myeloperoxidase were significantly higher in patients with an eroded plaque than in those with a ruptured plaque (median, 2500 ng/mL; 25th to 75th percentile, 1415 to 2920 versus median, 707 ng/mL; 25th to 75th percentile, 312 to 943; P=0.001), whereas C-reactive protein levels did not differ significantly (median, 11.3 mg/L; 25th to 75th percentile, 1.3 to 28.5 versus median, 3.9 mg/L; 25th to 75th percentile, 1.3 to 17.8; P=0.76, respectively). In addition, the density of myeloperoxidase-positive cells within thrombi overlying plaques in postmortem coronary specimens retrieved from sudden coronary death victims was significantly higher in lesions with erosion (n=11) than ruptures (n=11) (median, 1584; 25th to 75th percentile, 1,088 to 2,135 cells/mm(2) versus median, 579; 25th to 75th percentile, 442 to 760 cells/mm(2); P=0.0012).

CONCLUSIONS: Systemic myeloperoxidase levels are significantly elevated in patients with acute coronary syndrome presenting with eroded culprit plaque compared with patients presenting with ruptured culprit plaque. Consistently, in postmortem coronary specimens, luminal thrombi superimposed on eroded plaques contain a higher density of myeloperoxidase-positive cells than thrombi superimposed on ruptured plaques. This study supports the concept that elevations in selective inflammatory biomarkers reflect specific acute complications of coronary atherosclerosis.