Development of lipid-rich plaque inside bare metal stent: possible mechanism of late stent thrombosis? An optical coherence tomography study

Aims To study in-stent tissue characteristics by optical coherence tomography (OCT) at long-term follow-up in patients with previous bare metal stent implantation. Methods and results Among 1636 patients who underwent bare metal stent (BMS) implantation between 1999 and 2006, 39 patients with 60 BMS who developed recurrent ischaemia underwent repeat catheterisation and OCT imaging between June 2008 and August 2009. The average time interval between initial BMS implantation and OCT imaging was 6.5 +/- 1.3 years. A lesion that had features of lipid-rich plaque was found in 20 stents (33.3%) in 16 patients (41%). Fibrous intima was observed in the remaining 40 stents. In the group with lipid-rich plaque, average fibrous cap thickness was 56.7 +/- 5.8 mu m and lipid arc was 173 +/- 58. Six patients had evidence of recent plaque disruption and another six patients had mural thrombus. Hypertension and smoking were more common in these patients than in those with fibrous intima. Conclusions Lipid-rich plaque with a thin fibrous cap was seen in patients with previous BMS implantation and recurrent ischaemia at late follow-up. This may be one possible mechanism for late stent thrombosis.