Abstract 1955: Stent Fracture is One of the Leading Cause of Restenosis after Sirolimus-Eluting Stent Implantation
Background and Purpose: Recently, several cases of stent fracture (SFx) have been reported and suggested as a potential mechanism of restenosis after sirolimus-eluting stent (SES). We have performed this study to evaluate the incidence and patterns of SFx in restenotic lesions after SES implantation. Also, we reviewed and compared with fluoroscopic stent images of restenotic lesions of Bare metal stent (BMS, velocity®), a background stent of SES.
Methods: From May 2003 to June 2006, SES was implanted in 1105 lesions and BMS was implanted in 97 lesions. During the follow up, 24 restenotic lesions were observed in 22 patients (mean age: 57.1 ± 8.8years, male 19) who were implanted SES (mean length: 28.4 ± 5.01mm, diameter: 2.84 ± 0.29mm) and 30 cases (mean age: 60.3 ± 9.0years, male 23) with ISR in BMS group (mean length: 18.5 ± 6.03mm, diameter: 3.0 ± 0.43mm) from coronary angiography. Mean follow up duration of the patients with ISR in SES was 11.4 ± 6.3 months and that was 9.83 ± 5.9 months in BMS group. Based on fluoroscopy and intravascular ultrasound (IVUS) image, SFx was defined as the absence of stent strut compared with postintervention on follow up study.
Results: Of the 24 SES restenosis, 23 were focal (restenosis length < 10mm) ISR and one had diffuse restenosis from proximal to distal part of stent. Among the 23 focal ISR, 8 (33%) were SFx which has very focal restenosis on the breakpoint of stent. Also, the IVUS study of 8 cases showed complete absence of neointimal hyperplasia in the rest of the stent. All fractured stents were long (mean length: 30.2 ± 2.3mm, diameter: 2.88 ± 0.32mm) (p < 0.05). All fracture sites were proximal except one which was on overlap site of 2 SES. But, we couldn’t find SFx in the 30 patients with ISR after BMS implantation. Most cases had diffuse lesions (n = 18, 60%) and 2 cases had the pattern of total occlusion at stent proximal, too. 10 cases were focal lesions.
Conclusion: As compared with BMS, most lesions had the patterns of focal ISR in SES group. Also, SFx was one of the leading causes of focal ISR after SES implantation in our study. The effective suppression of neointimal formation may be the contributing mechanism of SFx in SES.