Coronary plaque rupture with subsequent thrombosis typifies the culprit lesion of non-ST-segment-elevation myocardial infarction, not unstable angina: non-ST-segment-elevation acute coronary syndrome study.

Recently, unstable angina pectoris (UAP) and non-ST-segment-elevation myocardial infarction (NSTEMI) have been considered together because they exhibit indistinguishable clinical and electrocardiogram features, and constitute non-ST-segment-elevation acute coronary syndrome (NSTE-ACS). However, no optical coherence tomography (OCT) studies have reported the association between vulnerable plaque morphology and clinical characteristics in NSTE-ACS patients based on assessment of clinical symptoms and myocardial necrosis. The aim of this study was to investigate the differences in clinical characteristics and plaque morphology assessed by OCT between patients with UAP and NSTEMI. Preinterventional OCT images of 84 NSTE-ACS patients were studied, 19 with NSTEMI and 65 with UAP, according to levels of high-sensitivity troponin T. The frequency of plaque rupture and thrombus in patients with NSTEMI was higher than in UAP patients with either class I or II + III (rupture: NSTEMI, 68 %; UAP classes II + III, 30 %; UAP class I, 19 %, thrombus: NSTEMI, 73 %; UAP classes II + III, 22 %; UAP class I, 14 %). In NSTEMI patients, the frequency of occurrence of both thrombus and rupture was the highest. Conversely, patients with UAP class I or those with UAP classes II + III most frequently had no thrombus and rupture, and the frequencies of the presence of thrombus were only 14 and 22 %, respectively. Multivariate analysis revealed that thrombus and plaque rupture were independently associated with NSTEMI. This study demonstrates that the morphological features of culprit lesions could be related to clinical severity in NSTE-ACS patients.