Coronary Plaque Rupture in Stable Coronary Artery Disease and Non-ST Segment Elevation Myocardial Infarction: An Optical Coherence Tomography Study

BACKGROUND: Plaque rupture (PR) is the main cause of coronary thrombosis in non-ST segment elevation myocardial infarction (NSTEMI), but can be found in stable coronary artery disease (CAD). Our study compared the morphology and local inflammatory activity of ruptured plaques between stable CAD and NSTEMI patients using frequency-domain optical coherence tomography (FD-OCT). METHODS: We retrospectively evaluated 70 plaques with PR at the FD-OCT (25 in stable CAD patients and 45 in NSTEMI patients). Main clinical, angiographic, and morphological features were compared. RESULTS: Besides an overall equivalence in clinical and angiographic features (except for more smokers among NSTEMI patients), some important FD-OCT differences in plaque morphology emerged: PR in NSTEMI was characterized by more macrophage infiltrates (78% in NSTEMI patients vs 20% in stable CAD patients; P<.001) and intraluminal thrombosis (84% in NSTEMI patients vs 48% in stable CAD patients; P<.01). Quantitative analysis showed a higher density of macrophages in NSTEMI than in stable CAD patients: median max normalized standard deviation (NSD) was 0.0934 (IQR, 0.0796-0.1022) vs 0.0689 (IQR, 0.0598-0.0787); P<.01 and mean NSD was 0.062 (IQR, 0.060-0.065) vs 0.053 (IQR, 0.051-0.060); P<.001. Other morphological features did not differ between stable CAD and NSTEMI patients. Main FD-OCT quantitative parameters like minimal lumen area and plaque length were also equivalent between the 2 groups. CONCLUSIONS: Differences in morphological features of PR between stable CAD and NSTEMI patients suggest that local inflammation contributes to the unstable fate of the atherosclerotic plaque.