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

This study assessed the incidence and course of healing of uncovered plaque ruptures (PR) following primary percutaneous coronary intervention.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.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.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 mm(2) [interquartile range (IQR): 4.8 to 9.3 mm(2)] to 3.6 mm(2) [IQR: 2.8 to 8.0 mm(2)]; p = 0.012). Proximal segments with uncovered PR had greater plaque volumes (62.1 mm(3) [IQR: 50.2 to 83.6 mm(3)] vs. 38.7 mm(3) [IQR: 29.6 to 47.6 mm(3)], respectively; p < 0.001), vessel volumes (110.7 mm(3) [IQR: 92.3 to 128.1 mm(3)] vs. 76.0 mm(3) [IQR: 63.8 to 100.3 mm(3)], 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.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.