Korean Circ J.  2007 Feb;37(2):58-63. 10.4070/kcj.2007.37.2.58.

Is Stent Underexpansion the Main Cause of In-Stent Restenosis after Sirolimus-Eluting Stent Implantation?: An Intravascular Ultrasound Study

• Kim BK
• Oh SJ
• Jeon DW
• Kim KH
• Yang JY

• KMID: 1859082
• DOI: http://doi.org/10.4070/kcj.2007.37.2.58

Abstract

BACKGROUND AND OBJECTIVES: Intravascular ultrasound (IVUS) can be useful for assessing the causes of in-stent restenosis (ISR) after sirolimus-eluting stent (SES) implantation. We used IVUS to evaluate the causes of ISR after SES implantation.
SUBJECTS AND METHODS
SES implantation was performed in 502 patients with 670 coronary lesions. Of these patients, 27 patients had angiographic ISR in 28 lesions. We evaluated the patterns of ISR and we wanted to elucidate the possible mechanism of ISR after SES implantation with using IVUS analysis.
RESULTS
The ISR pattern was focal in 26 lesions, and diffuse in 2 lesions, including 1 total occlusion. When analyzing the 21 IVUS-applicable lesions, stent underexpansion [the minimal stent cross-sectional area (CSA) was < 5 mm2 and it was < 4.5 mm2 in the cases of small coronary arteries (reference vessel diameter < 2.8 mm)] was observed in 10 lesions (48%). Stent fracture (defined as non-visualization of the struts on IVUS at the restenotic segments) and edge restenosis was identified in the 3 (14%) and 3 lesions (14%), respectively. Except for edge stenosis, stent underexpansion was observed in 55% of the intra-stent restenotic lesions and it was more prominent in the small coronary arteries (7/8 small coronary artery lesions). Stent underexpansion, stent fracture or edge restenosis were not related to the 7 ISR lesions (33%) in which profound intimal hyperplasia within the stent occurred.
CONCLUSION
Our observation of ISR after SES implantation with using IVUS showed that most ISR lesions have mechanical problems, especially stent underexpansion. However, one third of the ISR lesions were associated with profound intimal hyperplasia within the stent.

Keyword

Coronary restenosis; Stents; Ultrasonics

MeSH Terms

Constriction, Pathologic
Coronary Restenosis
Coronary Vessels
Humans
Hyperplasia
Stents*
Ultrasonics
Ultrasonography*

Figure

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  Fig. 1 In-stent restenosis caused by stent underexpansion after sirolimus-eluting stent implantation (SES). The pre-stenting (A) and post-stenting angiogram (B) are shown [overlapped with a SES 3.5×33 mm (dashed line) and a SES 2.75×33 mm (dotted line)]. Follow-up angiography (C) demonstrates 90% stenosis in mid-portion of the distal stent of the mid-left anterior descending artery (LAD). IVUS images are from 10 mm proximally (D), the minimal lumen site (E), and 10 mm distally (F) at follow-up. IVUS demonstrated stent underexpansion (minimal stent CSA=4.0 mm2) at the minimum lumen site.

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  Fig. 2 In-stent restenosis caused by stent fracture after implantation of sirolimus-eluting stent. Pre-stenting (A: left anterior oblique view. B: right anterior oblique view) and the poststenting angiogram (C) after implanting a 2.75×33 mm sirolimus-eluting stent are shown. Follow-up angiography (D) demonstrates 85% stenosis in the proximal portion of the right coronary artery: an arrow indicates the image slice of intravascular ultrasound (IVUS). Stent separation (arrowhead) of mid-portion of the sirolimus-eluting stent was noted on fluoroscopy (lower box in D). The follow-up IVUS images are 5 mm (E) and 2mm (F) proximal to the minimal lumen site (G), and 2 mm (H) and 5 mm (I) distal to the minimal lumen site. An IVUS investigation at the spot of the in-stent restenosis represents non-visualization of struts (G).

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