Significant stenosis without thrombus may be the third most common etiology of acute coronary syndrome

Abstract Background Plaque rupture (PR), plaque erosion (PE) and calcified nodule (CN) are known as major etiologies of acute coronary syndrome (ACS). On the other hand, significant stenosis without thrombus (SSWT) can be sometimes observed in culprit plaque of ACS. However, incidence and clinical feature of SSWT in ACS patients are not well known in Japanese. Method This is a sub study of TACTICS registry which include ACS patients (n=702) undergoing primary percutaneous coronary intervention (PCI) under optical coherence tomography (OCT) in Japan. Using this registry data, we compared the clinical features and OCT findings of SSWT in ACS patients in comparison with PR, PE and CN. Major adverse cardiac event (MACE) was defined as death, non-fatal myocardial infarction, heart failure, or ischemia-driven revascularization at 1-year. Results Plaque rupture (PR: n=411, 61%) and plaque erosion (PE: n=178, 26%) were 2 major etiologies, which was followed by SSWT (n=59, 9%) and calcified nodule (CN: n=28, 4%). Clinical characteristics are shown in table 1. Patients with SSWT was slightly older than PR and PE but younger than CN. Proportion of male was fewer than PR and PE but greater than CN. In terms of traditional coronary risk factors, there were significant differences in prevalences of diabetes, active smoking, and hemodialysis among different etiologies. In SSWT, non-ST elevation myocardial infarction was the main type of ACS followed by unstable angina and ST elevation myocardial infarction (51%, 39% and 10%, respectively), which may be associated with the least CK level and greater TIMI flow. Lesion was less complex with lower proportion of type B2 or C, shorter procedure time, lower proportion of multivessel disease and lower syntax score. OCT findings are shown in table 2. Regarding lipid component and calcification, SSWT showed similar finding as PE. Cholesterol crystal was relatively less as compared to PR and PE. Kaplan-Meier survival curve showing MACE and ischemia driven-TLR are shown in figure 1 and 2. MACE and TLR was the least in SSWT. Conclusion SSWT was the third most common etiology of ACS with different feature from PR, PE and CN.