Uncovered Culprit Plaque Ruptures in Patients With ST-Segment Elevation Myocardial Infarction Assessed by Optical Coherence Tomography and Intravascular Ultrasound With iMap.

OBJECTIVES: This study assessed the incidence and course of healing of uncovered plaque ruptures (PR) following primary percutaneous coronary intervention.

BACKGROUND: The infarct-related occlusion is frequently located at the lesion site with maximum thrombus burden, whereas the culprit PR may be situated more proximally or distally.

METHODS: Uncovered PR in segments adjacent to the stent were identified by optical coherence tomography and intravascular ultrasound using iMap (Boston Scientific, Marlborough, Massachusetts) within 48 h and after 12 months. The percentages of necrotic core, fibrotic tissue, lipid tissue, and calcific tissue were determined.

RESULTS: Eleven uncovered PR were found in 10 of 77 patients (13.0%). Eight of these ruptures (10.4%) were identified as culprit and were located proximal to the stent. Two patients were treated before follow-up due to recurrent symptoms. After 12 months, 3 PR had healed incompletely without causing symptoms. The lumen area at the PR site was reduced (7.5 mm2 [interquartile range (IQR): 4.8 to 9.3 mm2 ] to 3.6 mm2 [IQR: 2.8 to 8.0 mm2 ]; p = 0.012). Proximal segments with uncovered PR had greater plaque volumes (62.1 mm3 [IQR: 50.2 to 83.6 mm3 ] vs. 38.7 mm3 [IQR: 29.6 to 47.6 mm3 ], respectively; p < 0.001), vessel volumes (110.7 mm3 [IQR: 92.3 to 128.1 mm3 ] vs. 76.0 mm3 [IQR: 63.8 to 100.3 mm3 ], respectively; p < 0.001), and greater percentages of necrotic core (34.0% [IQR: 29.0% to 44.5%] vs. 20.5% (IQR: 10.0% to 29.0%]; p < 0.001). Conversely, percentages of fibrotic tissue were lower (44.0% [IQR: 32.0% to 47.0%] vs. 56.0% [IQR: 46.0% to 66.0%]; p = 0.001), whereas no differences were found for lipid tissue and calcific tissue.

CONCLUSIONS: Uncovered culprit ruptures detected by optical coherence tomography were common following primary percutaneous coronary intervention and were found to be associated with significant lumen reduction during the healing process.