Comparisons of detailed arterial healing response at seven months following implantation of an everolimus- or sirolimus-eluting stent in patients with ST-segment elevation myocardial infarction

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Abstract

Background

The difference of arterial healing response following everolimus-eluting stent (EES) or sirolimus-eluting stent (SES) implantation in patients with ST-segment elevated myocardial infarction (STEMI) has not been compared in detail.

Methods

Thirty-five patients with STEMI were randomly implanted with an EES or SES (23 EES, 12 SES). At seven months, neointimal thickness (NIT) and strut malapposition were evaluated by optical coherence tomography (OCT) and the grade and heterogeneity of neointimal coverage (NIC) and development of intra-stent thrombi were evaluated by angioscopy.

Results

No significant differences were noted in clinical events experienced by the two groups, although one patient with an EES died following a papillary muscle rupture and one patient with a SES experienced sub-acute stent thrombosis. On OCT, although the EES implants showed a greater NIT than the SES implants (94.8 ± 88.8 μm vs 65.6 ± 63.3 μm, P < 0.0001), both the EES and SES showed an excellent suppression of neointimal proliferation in the culprit lesion of STEMI. The frequency of uncovered and malapposed struts of EES was significantly lower than that of SES (2.7% vs. 15.7%, P < 0.0001, 0.7% vs. 2.3%, P < 0.0001, respectively). The ratio of stents fully covered with neointima of EES group was significantly higher than that of SES group (P = 0.04). Angioscopic analysis also showed greater dominant NIC grade with homogenous NIC in EES than in SES (P = 0.03, P = 0.0002, respectively). The incidence of massive intra-stent thrombus of EES was lower than that of SES (P = 0.05).

Conclusion

For patients with STEMI, EES may promote better arterial healing response than SES.

Introduction

The preferred treatment of patients with ST-segment elevation myocardial infarction (STEMI) is primary percutaneous coronary intervention (PCI) with stent implantation [1], [2]. However, drug-eluting stent (DES) implantation in patients with STEMI is controversial as several studies have demonstrated that vessel healing at the culprit site is substantially delayed after DES implantation compared with that in patients with stable angina [3], [4], [5], [6], [7], [8]. Further, exposed and malapposed stent struts, which may be associated with late stent thrombosis, were more common after DES than bare metal stent implantation, especially in patients with STEMI [9].

The everolimus-eluting stent (EES) is a second-generation DES, in which everolimus, an anti-proliferative agent, is released from thin, non-adhesive, durable, biocompatible fluoropolymer coated onto a low-profile, flexible cobalt–chromium stent [10], [11]. In non-STEMI patients, EES implants are reported to induce more favorable vascular responses, such as a lower incidence of uncovered struts and intracoronary thrombus, than sirolimus-eluting stents (SES) despite similar neointimal thickness [11], [12]. Although EES treatment is a possible option for the treatment of patients with STEMI, the detailed vessel healing response after EES implantations in patients with STEMI has not been fully clarified.

The aim of this study was to evaluate the detailed arterial healing response following implantation of second-generation EES in patients with STEMI using optical coherence tomography (OCT) and angioscopy, and to compare the healing response with that of first-generation SES.

Section snippets

Study design

This study was a single-center, randomized controlled trial designed to compare EES (PROMUS, Boston Scientific Corp, Xience V, Abbott Vascular) and SES (Cypher Select, Cordis Corp) in patients with STEMI.

Ninety-eight consecutive patients with STEMI who visited Hyogo Prefectural Awaji Hospital between February 2010 and July 2011 and who met the following inclusion criteria were considered as candidates for the study: 1) patients presenting with symptoms of acute myocardial infarction < 24 h before

Results

No significant differences in clinical characteristics, concomitant medications, laboratory data, or cardiac function were observed between the two groups at the beginning of the study (Table 1). Average time from PCI to follow-up angiography was 207.3 ± 15.7 days in EES group and 205.8 ± 12.9 days in the SES group (P = 0.81).

Although one patient in the EES group died from a ruptured papillary muscle three days after stent implantation and one patient in the SES group occurred sub-acute stent

Discussion

The present study represents the first in-vivo report investigating detailed arterial healing response to the second generation EES in patients with STEMI by both OCT and angioscopy. We found that both the EES and SES showed an excellent suppression of neointimal proliferation in the culprit lesion in patients with STEMI. Although the EES implants showed a greater neointimal proliferation than the SES implants, the difference was small and was not associated with clinical events, such as

Study limitation

Several limitations to this study warrant mention. First, this is a single center study with a limited sample size, which may cause selection bias and fail to detect differences in clinical events in different treatments. Second, our study population comprised patients with STEMI; hence, PCI procedures were completed urgently, which might induce operator bias in the PCI procedure. Third, because the present study was not designed to compare treatment for STEMI and non-STEMI patients, the

Conclusion

For patients with STEMI, EES may promote better arterial healing response than SES. EES treatment should be considered a safe and effective option for the treatment of patients with STEMI.

References (38)

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