Naoki Yoshino

Delayed Neointimalization on Sirolimus-Eluting Stents : 6-Month and 12-Month Follow up by Optical Coherence Tomography

BACKGROUND Sirolimus-eluting stents (SES) have incomplete neointimal coverage at 6-month follow up as determined with optical coherence tomography (OCT). The long-term detailed changes of neointima in SES remains to be clarified. METHODS AND RESULTS Serial changes in neointimal coverage of SES from 6 months to 12 months using OCT were examined. Of 21 SES in 13 patients, OCT was used to visualize 2,321 stent struts at 6 months and 2,285 stent struts at 12 months. The frequency of struts without neointimal coverage decreased from 6 months to 12 months (from 10.4 to 5.7%). The frequency of malapposed struts decreased from 6 months to 12 months (from 1.7 to 0.2%). The average thickness of the neointima increased (from 112 +/-123 to 120 +/-130 microm). The frequency of struts located at the side branch orifice without neointima decreased (from 4 out of 17 (24%) to 0 out of 17 (0%)). Complete coverage with neointima was observed in 14% (3 of 21 SES) at 6 months, and 24% (5 of 21 SES) at 12 months. CONCLUSIONS Additional neointimal coverage was observed between 6 and 12 months, with a small increase in the neointimal thickness. The incidence of complete coverage, however, was still low at 12 months. These findings suggest delayed neointimalization on SES.

Optical coherence evaluation of everolimus-eluting stents 8 months after implantation

Objective The aim of this study was to evaluate detailed vessel response after everolimus-eluting stents (EES) implantation in human de novo coronary lesions by optical coherence tomography (OCT). Design, setting and patients Between November 2008 and October 2009, 25 patients (14 men, 65.5±8.6 years) with de novo native coronary artery lesions were implanted with 30 EES, and OCT was performed at 8 months post-implantation. Main outcome measures Neointimal thickness (NIT) on each strut, strut apposition to the vessel wall, the frequency of struts surrounded by low intensity area and the incidence of intra-stent thrombus were analysed. To evaluate the radial unevenness of NIT, the difference between the maximum and minimum NIT (dNT) was calculated for each cross-section. Results At 236±39 days after implantation, there were no major adverse cardiac events, nor target vessel revascularisation. A total of 5931 struts was evaluated by OCT. The median NIT was 80 μm (25th and 75th percentile 50 μm and 140 μm) and average NIT was 100±74 μm. The number of neointima-covered struts was 5834 (98.4%), and 31 (0.52%) struts showed malapposition without neointimal coverage. The number of struts surrounded by low intensity area was 452 (7.62%). Eleven EES (37%) showed full neointimal coverage. No intra-stent thrombus was detected. The average dNT was 108±77 μm. Conclusions Most EES struts were covered with uniform and thin neointima. The frequency of low-intensity neointima was very low, which may be a result of promoted vessel healing. These results may support improved clinical outcomes with EES in clinical trials.

Very late thrombosis of sirolimus-eluting stent due to late malapposition: Serial observations with optical coherence tomography

A 54 years old man underwent directional coronary atherectomy in segment 7 with a partial deep-cut injury. A sirolimus-eluting stent (SES) was implanted at the restenosed post-atherectomy lesion. Six months after SES implantation, intravascular ultrasound (IVUS) examination revealed slight vessel enlargement although there were no malapposed struts. Optical coherence tomography (OCT) revealed partial stent malapposition. Ticlopidine was discontinued 3 months after SES implantation, but aspirin was continued. Twenty-nine months after SES implantation, after discontinuing aspirin for 7 days for colon polypectomy, the patient suffered an acute myocardial infarction at the SES implantation site. IVUS revealed further positive vessel remodeling and slight stent malapposition and OCT revealed extension of the previous stent malapposition and ulcer-like appearance around the stent struts. This case demonstrates that even a small partial SES malapposition that can be detected only by OCT has the potential to enlarge over time and the late malapposition may result in late thrombosis when anti-platelet therapy is discontinued.