Characteristics of Late-Acquired Incomplete Stent Apposition: A Comparison With First-Generation and Second-Generation Drug-Eluting Stents.

OBJECTIVE

This study aim was to investigate the morphometric parameters of late-acquired incomplete stent apposition (ISA) following use of Cypher sirolimus-eluting stent (SES; Cordis), Taxus paclitaxel-eluting stent (PES; Boston Scientific), and Resolute zotarolimus-eluting stent (ZES; Medtronic).

BACKGROUND

Characteristics of late-acquired ISA between first-generation and second-generation drug-eluting stents (DESs) have not been systematically examined.

METHODS

Late-acquired ISA was defined as separation of at least 1 stent strut from the vessel wall with evidence of blood speckle behind the strut, where poststent implantation intravascular ultrasound (IVUS) revealed complete apposition. A total of 30 late-acquired ISA cases (12 SES, 10 PES, 8 ZES) were included in this IVUS analysis. Corresponding cross-sections at post procedure were selected for comparison. Vessel, lumen, peristent tissue, and stent area were measured in the late-acquired ISA arc as referenced to stent center.

RESULTS

Late-acquired ISA area was 2.4 ± 1.5 mm² in SES, 2.2 ± 2.7 mm² in PES, and 0.9 ± 0.6 mm² in ZES (P=.02 for SES vs ZES). Vessel area increased from post procedure to follow-up in SES (4.6 ± 1.7 mm² to 7.0 ± 2.5 mm²; P<.01) and PES (3.6 ± 1.7 mm² to 5.7 ± 3.8 mm²; P=.06), but not in ZES. Vessel expansion was the main mechanism in SES and PES groups; however, tissue regression and stent recoil, as well as vessel expansion, also contributed to late-acquired ISA in ZES. Per-patient analyses demonstrated that vessel expansion was the predominant mechanism of late-acquired ISA in 83% of SES, 60% in PES, and 50% of ZES cases.

CONCLUSION

The magnitude and mechanism of late-acquired ISA appear to be different between first-generation and second-generation DESs, possibly due to varying vessel response to different stent component types.