The aim of this study was to evaluate neointimal coverage obtained using a new method of polytetrafluoroethylene-covered stent (PCS) implantation combined with underlying longer sirolimus-eluting stent (SES) implantation using optical coherence tomography. Nine patients were enrolled in this study, including patients with coronary artery perforations, original coronary aneurysms, and acquired coronary aneurysms after drug-eluting stent implantation. All patients were first treated with long SES implantation and then with focal PCS implantation. Postprocedural and follow-up angiographic and optical coherence tomographic examinations were performed in all patients, and intravascular ultrasound was performed in 5 patients. All patients were asymptomatic during follow-up, without recurrent angina. There was no stent-edge or stent-segment binary restenosis. Values of late loss for proximal SES segments, PCS segments, and distal SES segments were similar (0.09, 0.07, and 0.04 mm, respectively, p = 0.8113). The mean neointimal thickness of PCS was less than that of proximal and distal SES. However, no malapposed cross sections or uncovered cross sections were found in PCS segments compared with SES segments (p = 0.0011). In conclusion, the combination of PCS and underlying longer SES implantation can offer better angiographic follow-up results. High-resolution optical coherence tomography provided convincing proof of full neointimal coverage of PCS. This new method of combined PCS and SES implantation may be a better choice compared with direct PCS implantation in certain clinical settings.
A stent graft (covered stent) with the integration of a membrane into a coronary stent can possibly prevent intraluminal proliferation, to seal degenerated vein grafts, prevent the no-reflow phenomenon, and cover coronary artery perforations, symptomatic aneurysms, and fistulae with high success and acceptable rates of acute complications. With the broad clinical use of drug-eluting stents (DES) to treat coronary artery lesions, late coronary aneurysms caused by late stent malapposition after DES implantation indicate the need for polytetrafluoroethylene-covered stents (PCS). The incidence of late coronary aneurysm with bare-metal stent implantation is 0.2%, compared with 1.4% with DES implantation. Some angiographic follow-up data after PCS-only implantation have shown that restenosis (especially at the stent edge) and thrombotic occlusion often occur in the stented segment. A few case reports have shown delayed endothelialization after PCS implantation for coronary aneurysm, which maybe the reason for subacute thrombosis and restenosis in PCS. However, serial observations of neointimal coverage after PCS implantation are limited. In this study, we evaluated the neointimal coverage obtained using a new method of PCS implantation combined with underlying longer sirolimus-eluting stent (SES) implantation using follow-up observations on optical coherence tomography (OCT).
Methods
Nine consecutive patients were observed in this study from January 2007 to September 2011. All patients were treated with longer SES and then focal PCS on the basis of SES. Indications for covered stent implantation were coronary artery perforations after SES implantation in 3 patients, original coronary aneurysms in 2 patients, and late coronary aneurysms caused by late malapposition of DES in 4 patients. Lesion characteristics before combined stent implantation were detected by OCT in 6 patients, except for those with perforations. Postprocedural and follow-up angiography and OCT were performed in all patients, and intravascular ultrasound (IVUS) was performed in 5 patients. All patients were given dual-antiplatelet therapy after combined stent implantation. This protocol was approved by the hospital ethics committee, and all patients provided informed consent.
Coronary angiograms were analyzed using quantitative coronary angiographic analysis software (Advantage Workstation version 4.2; GE Healthcare, Milwaukee, Wisconsin) by 2 angiographers who were blinded to clinical information.
OCT was performed using the time-domain M3 system. The technique of intracoronary OCT has previously been described. Optical coherence tomographic image analysis was performed by 2 investigators who were blinded to clinical information. When there was discordance between the readers, a consensus reading was obtained from a third independent investigator.
For coronary aneurysms, maximal cross-sectional aneurysmal area was measured. Lines connecting the endoluminal surface of the neointima and the stent strut were drawn semiautomatically by optical coherence tomographic off-line analysis software (LightLab Imaging, Westford, Massachusetts). Maximum, minimum, and mean neointimal thickness, uniformity of intima, stent area, luminal area, and neointimal area for each cross-sectional image were automatically calculated. An uncovered cross section was considered when ≥1 stent strut was not covered with neointima. Stent malapposition was defined as ≥1 stent strut clearly separated from the vessel wall when the distance between its inner surface reflection and the vessel wall was more than the strut thickness plus the polymer thickness plus the resolution of OCT (>130 μm in this study).
The IVUS system (iLab version 1.3; Boston Scientific Corporation, Fremont, California) used a 40-MHz, 2.6Fr catheter. Images were acquired by automatic pullback at 1.0 mm/s. Off-line analysis was performed using iLab version 1.3.
All statistical analysis was performed by an independent statistician in the Biostatistical Department at Harbin Medical University. Categorical data are expressed as frequencies and percentages and continuous variables as mean ± SD. Continuous variables were compared using Student’s t test or the Kruskal-Wallis test on the basis of the distribution. All analysis was performed using SAS version 9.1.3 (SAS Institute Inc., Cary, North Carolina). A p value <0.05 was required for statistical significance.
Results
PCS and underlying SES were successfully implanted in culprit lesions in all patients. Except for patients with coronary artery perforations, who already had underlying SES, SES were implanted first with full dilatation. PCS were implanted in the middle segments of underlying SES with ≥3 mm proximal or distal SES segment. The mean SES diameter and length were 3.1 ± 0.4 and 29.9 ± 7.1 mm, respectively. The mean PCS diameter and length were 3.4 ± 0.2 and 19.7 ± 6.1 mm, respectively. All PCS were dilated using noncompliant balloons of the same size (20 to 23 atm). Postprocedural angiography and OCT ensured optimal final minimal luminal diameter, acute gain, and good SES or PCS strut apposition ( Figures 1 and 2 ). The average follow-up time was 9.4 ± 3.4 months.
Coronary angiography showed good results after PCS implantation, with the sealing of vascular wall perforations or aneurysms ( Figures 1 and 2 ). All patients were asymptomatic during follow-up, without recurrent angina. Minimal luminal diameter and reference vessel diameter after percutaneous coronary intervention were comparable among proximal SES segments, PCS segments, and distal SES segments (p >0.05). There was no stent-edge or stent-segment binary restenosis. Values of late loss for proximal SES segments, PCS segments, and distal SES segments were similar (0.09, 0.07, and 0.04 mm, respectively, p = 0.8113; Table 1 ).
| Patient | Post-PCI Reference Vessel Diameter (mm) | Post-PCI Minimal Luminal Diameter (mm) | Late Loss (mm) | Mean Neointimal Thickness (μm) | Percentage of Uniformity of Intima | Malapposed or Uncovered Cross Section | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Proximal SES | PCS | Distal SES | Proximal SES | PCS | Distal SES | Proximal SES | PCS | Distal SES | Proximal SES | PCS | Distal SES | Proximal SES | PCS | Distal SES | Proximal SES | PCS | Distal SES | |
| 1 | 4.0 | 4.0 | 3.9 | 3.7 | 3.9 | 3.7 | 0.25 | 0.23 | 0.16 | 359.5 | 215.0 | 183.3 | 74 | 79 | 86 | 0 | 0 | 0 |
| 2 | 3.1 | 3.2 | 3.0 | 2.9 | 2.9 | 2.7 | 0 | 0 | 0 | 22.5 | 39.2 | 11.4 | 64 | 76 | 75 | 0 | 0 | 0 |
| 3 | 3.0 | 3.1 | 2.9 | 2.8 | 2.8 | 2.8 | 0.04 | 0 | 0.02 | 104.5 | 66.7 | 96.7 | 77 | 72 | 73 | 3 | 0 | 0 |
| 4 | 3.0 | 3.0 | 3.0 | 2.9 | 2.9 | 2.8 | 0.02 | 0.02 | 0 | 85.2 | 53.3 | 55.0 | 78 | 86 | 95 | 0 | 0 | 0 |
| 5 | 3.2 | 3.2 | 3.1 | 3.0 | 3.1 | 3.0 | 0.09 | 0.06 | 0.05 | 135.9 | 67.6 | 113.3 | 77 | 87 | 84 | 0 | 0 | 1 |
| 6 | 3.2 | 3.2 | 3.1 | 3.0 | 2.9 | 2.9 | 0.23 | 0.16 | 0.05 | 203.3 | 213.3 | 143.3 | 75 | 90 | 90 | 1 | 0 | 0 |
| 7 | 4.0 | 4.0 | 3.9 | 3.8 | 3.8 | 3.5 | 0 | 0.01 | 0 | 35.6 | 50.0 | 40.0 | 94 | 91 | 62 | 0 | 0 | 0 |
| 8 | 3.5 | 3.4 | 3.5 | 3.2 | 3.2 | 3.1 | 0.01 | 0 | 0 | 51.4 | 54.8 | 75.0 | 92 | 86 | 82 | 1 | 0 | 0 |
| 9 | 3.1 | 3.0 | 3.0 | 3.0 | 3.1 | 3.1 | 0.21 | 0.17 | 0.09 | 165.1 | 84.2 | 120.9 | 83 | 72 | 74 | 0 | 0 | 0 |
| Mean ± SD/total | 3.3 ± 0.4 | 3.3 ± 0.4 | 3.3 ± 0.4 | 3.1 ± 0.4 | 3.2 ± 0.4 | 3.1 ± 0.3 | 0.09 ± 0.11 | 0.07 ± 0.09 | 0.04 ± 0.05 | 116.4 ± 39.8 | 70.2 ± 56.6 | 91.7 ± 78.3 | 78 ± 10 | 82 ± 11 | 82 ± 13 | 5 (18.5%) | 0 (0%) | 1 (2.5%) |
| p value | 0.9963 | 0.6762 | 0.4429 | 0.0006 | 0.5852 | 0.0011 | ||||||||||||
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