New insights by optical coherence tomography into the differences and similarities of culprit ruptured plaque morphology in non-ST-elevation myocardial infarction and ST-elevation myocardial infarction.

BACKGROUND

Plaque rupture is the most common pathology associated with non-ST-elevation myocardial infarction (NSTEMI) and ST-elevation myocardial infarction (STEMI). However, limited data are available regarding ruptured plaque morphology and its relationship with the clinical syndrome. This study aimed (1) to provide a morphologic description of ruptured culprit lesions by optical coherence tomography (OCT) and (2) to investigate whether ruptured plaque morphology differs between NSTEMI and STEMI.

METHODS

We included 84 consecutive patients with NSTEMI and STEMI undergoing OCT study of the culprit lesion. We identified patients with plaque rupture in the OCT study and used them as the study population. Qualitative and quantitative analysis of ruptured plaque morphology was then performed, followed by a comparison of the morphological characteristics in patients with STEMI and NSTEMI.

RESULTS

Fifty-five patients (70.5%) with rupture, 25 with NSTEMI, and 30 with STEMI were used for analysis. Plaque was ruptured at the minimal lumen in 34.5% of the cases, whereas 69% of the ruptures occurred at the plaque shoulder. Ruptured cap thickness was ≤90 μm in 96% of ruptured plaques. Patients with NSTEMI had greater minimal luminal area (P < .001), less lipid content (P = .01), and lower rupture length (P < .001) and length of missing fibrous cap (P < .05) compared with patients with STEMI.

CONCLUSIONS

Rupture of the plaque in myocardial infarction usually occurs in sites different than the minimal lumen and at the shoulder of areas with fibrous cap measuring ≤90 μm. Patients with STEMI have greater plaque disruption and smaller minimal lumen area than patients with NSTEMI.