Thin-cap fibroatheroma and increased coronary intima-media thickness are associated with an altered balance of arginine metabolites.

ABSTRACT

INTRODUCTION: Arginase inhibition increases plasma citrulline and citrulline / ornithine (C/O) ratio, and reduces plasma ornithine and ornithine / arginine (O/A) ratio in an animal model of myocardial infarction (MI). OBJECTIVES: We hypothesized that the presence of thin­cap fibroatheroma (TCFA) in the culprit lesion and increased non­culprit intima­media thickness of an infarct­related artery (IRA) are associated with an altered balance of arginine metabolites. PATIENTS AND METHODS: Arginine and its metabolites were measured using liquid chromatography and tandem mass spectrometry in 100 consecutive MI patients upon admission and at 6­month follow­up. TCFA and adjacent to culprit lesion proximal and distal 10­mm segments were assessed with optical coherence tomography in the acute phase. Twenty five patients without coronary lesions on angiography served as controls. RESULTS: The C/O ratio increased 5.33 times (P <0.001), while the O/A ratio decreased 2.53 times (P <0.001) at the 6­month follow­up, as compared with the acute phase of MI. The patients with (n = 75) vs without (n = 25) TCFA had lower C/O ratio by 29% (P = 0.003), while the mean intima­media diameter of adjacent non­culprit region correlated with the follow­up O/A ratio (R = 0.337; P = 0.003). In a multivariable analysis, a higher acute phase C/O ratio was associated with a lower risk of TCFA presence (odds ratio, 0.978; 95% CI, 0.962-0.994; P = 0.006), whereas a higher follow­up O/A ratio correlated with larger intima­media diameter of the adjacent segments (ß coefficient, 0.227; 95% CI for ß coefficient, 0.045-0.409; P = 0.018). CONCLUSIONS: Enhanced arginase activity over nitric oxide synthase following ischemia was associated with the presence of TCFA in the culprit lesion, while a similar metabolic shift in the chronic phase correlated with a greater thickness of the intima­media in the adjacent non­culprit IRA segments.