Endothelial dysfunction in plaque rupture and plaque erosion.

Vascular endothelial function plays an important role in the pathophysiology of acute coronary syndrome (ACS). Plaque erosion (PE) and plaque rupture (PR) are the two major mechanisms of ACS; however, how the vascular endothelial function differs between these etiologies is not well understood. Flow-mediated dilation (FMD) is a method used to evaluate the endothelial function. We aimed to assess endothelial function using FMD in patients with PE and PR. ACS patients (N = 160) who underwent primary percutaneous coronary intervention (PCI) with optical frequency domain imaging (OFDI) and FMD assessment were retrospectively enrolled. Culprit plaques were categorized as PE or PR based on OFDI. Based on the median value of FMD (4.1%) in our data, patients were classified into high-FMD (> 4.1%) and low-FMD (≤ 4.1%) groups. Based on the plaque type and FMD values, the patients were divided into PR-HighFMD (N = 48), PR-LowFMD (N = 47), PE-HighFMD (N = 33), and PE-LowFMD (N = 32) groups, and then the clinical characteristics were compared. Major adverse cardiac events (MACE) were defined as cardiovascular death, nonfatal myocardial infarction, stroke, ischemia-driven revascularization, hospitalization for angina or heart failure. FMD was similarly impaired in the PE and PR groups (4.2% vs. 4.1%, P = 0.85). Most clinical characteristics did not differ between the groups. The PR-High_FMD group showed the highest MACE-free survival, followed by the PE-Low_FMD (HR = 2.62, CI = 0.58-11.7, P = 0.21), PE-High_FMD (HR = 3.18, CI = 0.76-13.3, P = 0.11), and PR-Low_FMD (HR = 5.44, CI = 1.55-19.1, P = 0.008) groups. FMD is likely to have a prognostic impact on patients with ACS, which might vary depending on the culprit lesion.