Background. Culprit lesions of ST-segment elevation myocardial infarction (STEMI) patients are friable, soft, and prone to disruption during primary percutaneous coronary intervention (pPCI). The... Show moreBackground. Culprit lesions of ST-segment elevation myocardial infarction (STEMI) patients are friable, soft, and prone to disruption during primary percutaneous coronary intervention (pPCI). The presence of dissections in reference vessel segments (RVSs), adjacent to stented culprit lesions, and dynamic luminal changes in proximal or distal RVSs have not yet been investigated. We therefore sought to assess the healing patterns of edge dissections and the changes of lumen area at RVSs within 1 week post stent implantation in patients with STEMI. Methods. In the MATRIX trial (ClinicalTrials.gov NCT01433627), optical coherence tomography (OCT) was performed at the end of pPCI and within 1 week during staged PCI. The RVS dissection was defined as: type 1 = flap; type 2 = cavity; type 3 = double barrel; and type 4 = fissure. We compared separately the fate of residual dissection and luminal area/dimension by OCT in the target vessel between pPCI and staged PCI, including 1-year clinical outcomes. Results. Out of 151 patients, 46 patients had dissections in 50 RVSs and did not experience worse clinical outcome. Dissections were 44% type 1, 28% type 2, 12% type 3, and 16% type 4. Overall, 18% of the dissections healed. The mean lumen area of the RVS enlarged in 82 patients (59%) from pPCI to staged PCI. Compared with the proximal RVS, there was a significant increase in the lumen diameter at the distal RVS (0.06 +/- 0.25 mm vs -0.01 +/- 0.21 mm; P=.01). Conclusion. Dissections occur frequently after pPCI. One-fifth of them heal within 1 week and do not seem to negatively impact clinical outcomes. Distal RVS lumen area increased compared with proximal RVS, likely reflecting a different vasoconstriction pattern over time. Show less
