Influence of Plaque Characteristics on Early Vascular Healing in Patients With ST-Elevation Myocardial Infarction

To compare the early vascular healing of ruptured plaques (RP) and non-ruptured plaques (NRP) one month after primary percutaneous coronary intervention (PCI) in patients with ST-segment elevation myocardial infarction (STEMI), using optical coherence tomography (OCT).

Vascular healing and strut coverage are important factors in reducing the risk of stent thrombosis after PCI. Influence of underlying lesion characteristics and differences in healing response between RP and NRP are unknown.

Twenty-six STEMI-patients underwent PCI and implantation of a polymer-free drug-coated Biofreedom stent (BF-BES). OCT was performed pre-PCI, post-PCI and at 1-month follow-up. The patients were divided into two groups: RP = 15 and NRP = 11. OCT analyses of culprit lesion, post stent implantation at baseline and follow-up were performed to determine the difference in vascular healing based on presence of uncovered and/or malapposed stent struts and intraluminal filling defects.

The stent coverage did not differ significantly between the two groups at 1-month follow-up with percentage of uncovered struts: RP 26.5% [IQR 15.0-49.0] and NRP 28.1% [IQR 15.5-38.8] for NRP (p = 0.78). At 1-month, RP showed an increased percentage of late acquired malapposed struts (1.4% [IQR 0.8-2.4] vs. 0.0% [IQR 0.0-1.4], p = 0.03) and a larger total malapposition area (1.3 mm² [IQR 0.4-2.5] vs. 0.0 mm² [IQR 0.0-0.9], p = 0.01), compared to NRP.

Three out of four struts were covered within one month after stenting. The vascular healing was comparable in RP and NRP on stent coverage. However, RP had more and larger late acquired malapposition areas.