Two-year follow-up intravascular ultrasound analysis after bare metal stent implantation in 120 lesions

Serial changes of neointimal tissue after everolimus-eluting stent implantation in porcine coronary artery: an optical coherence tomography analysis

Purposes. The serial changes in neointimal tissues were compared between everolimus-eluting stent (EES) and bare-metal stent (BMS) in the porcine coronary artery using optical coherence tomography (OCT). Methods. Serial (1, 3, and 6 month follow-up after stent implantation) OCT examinations were performed in 15 swine with 15 BMS- and 15 EES-treated lesions in porcine coronary arteries. Results. In BMS-implanted lesions, neointimal volume decreased from 7.3 mm³ to 6.9 mm³ and 6.4 mm³ at 1, 3, and 6 months follow-up without statistical significance (P = 0.369). At the time points of 1, 3, and 6 months, neointimal tissue appearance was mainly a homogeneous pattern (80.0%, 93.3%, and 100%, resp.), while the other pattern was layered. In contrast, in EES-implanted lesions, neointimal volume significantly increased from 4.8 mm³ to 9.8 mm³ between 1 and 3 months but significantly decreased to 8.6 mm³ between 3 and 6 months (P < 0.001). Between 1 and 3 months, the layered pattern of neointimal tissue increased from 26.7% to 66.7% but decreased to 20.0% between 3 and 6 months. Conclusions. EES had a biphasic pattern of neointimal amounts that correlated with changes in neointimal morphology.

Angiographic evidence of progressive lumen narrowing over 2 years following drug-eluting stent implantation

BACKGROUND

Questions persist regarding the ability of drug-eluting stents (DES) to inhibit intimal growth in the long-term.

METHODS

We prospectively enrolled 766 lesions treated with DES that underwent angiographic examination at 6 months and 2 years after stenting. Lesions with 6-month restenosis (>50% of visual stenosis) were excluded. The primary end point was quantitative change in minimal lumen diameter (MLD) according to serial angiography of the segment (in-segment), the stented region (in-stent) and both edges. Late loss, defined as MLD change, was categorized as early (between post-procedure and 6 months), delayed (between 6 months and 2 years), or overall (between post-procedure and 2-years).

RESULTS

MLD progressively decreased in both the in-stent and edge regions at both 6 months and 2 years (p<0.001 in all paired analyses). In-segment MLD decreased from a median 2.27 mm (interquartile range; 1.98, 2.62) at post-procedure to 2.18 mm (1.86, 2.47; p < 0.001 with post-procedure) at 6 months, and to 2.02 mm (1.66, 2.37; p<0.001 with 6 months) at 2 years. Late loss was 0.0 6 mm (-0.05, 0.26) in the early phase, 0.09 mm (-0.01, 0.28) in the delayed phase, and 0.20mm (0.03, 0.50) overall. Two-year angiographic restenosis occurred in 54 (7.0%) lesions, and 65 (8.5%) underwent target lesion revascularization over a median follow-up of 52.5 months.

CONCLUSION

Serial angiographic analysis showed that DES lumen diameter progressively narrowed over 2 years post-procedure. However, the incidence of target lesion revascularization was relatively low due to the small amount of late loss in the delayed phase.

Impact of In-Stent Minimal Lumen Area at 9 Months Poststent Implantation on 3-Year Target Lesion Revascularization–Free Survival

Background— Intravascular ultrasound (IVUS) is used to assess intermediate lesions in native coronary arteries; minimum lumen area (MLA) <4.0 mm 2 is accepted as a cutoff for a significant stenosis. We evaluated the IVUS in-stent MLA at 9-month follow-up that best predicted subsequent target lesion revascularization (TLR)–free survival in patients from the TAXUS IV, V, and VI studies.

Methods and Results— In the combined TAXUS IV, V, and VI randomized trials, 9-month IVUS was available in 635 patients (331 treated with paclitaxel-eluting stents [PES] and 304 treated with bare-metal stents [BMS]) who did not require TLR in the first 9 months postintervention and who were followed for 3 years. The in-stent MLA that best predicted 3-year TLR-free survival was determined. At 9-months follow-up, IVUS-measured in-stent MLA was 5.7�2.3 mm 2 in the PES group and 4.8�2.3 mm 2 in the BMS group. Between 9 months and 3 years, TLR was required in 4.9% of patients who were treated with PES and 6.7% of patients who were treated with BMS. Multivariate analysis identified MLA at 9 months as a significant predictor of late TLR (hazard ratio, 0.63 [0.43–0.93]; P =0.02). The ability of MLA to predict late TLR was further assessed using receiver operating characteristic analysis. MLA was found to be an acceptable discriminator for both PES (c=0.7448) and BMS (c=0.7329). Finally, the optimal thresholds of MLA that best predicted subsequent TLR-free survival were determined to be 4.2 mm 2 for PES and 4.0 mm 2 for BMS.

Conclusion— In the combined IVUS analysis of TAXUS IV, V, and VI, patients who did not require TLR within the first 9 months had a high subsequent TLR-free survival rate whether treated with PES or BMS. MLA measured by IVUS at 9 months predicted subsequent TLR with a cutoff similar to intermediate, de novo lesions in native coronary arteries.

Induction of vascular atrophy as a novel approach to treating restenosis. A review

Regardless of the type of arterial reconstruction, luminal narrowing (stenosis or restenosis) develops in approximately one third of the vessels. In the past, the focus of research has been on the mechanisms of stenosis (intimal hyperplasia, pathologic remodeling) and pharmacologic approaches to prevention. An alternative approach is to induce intimal atrophy after luminal narrowing has developed, thus limiting treatment to only those patients that develop a problem. This approach to treat established disease by reducing wall mass through induction of cell death and extracellular matrix removal would be particularly useful for treating stenosis in synthetic bypass grafts or stented vessels, in which intimal hyperplasia is the primary mechanism of stenosis. This approach may be applicable as well to other vascular proliferative disorders, such as pulmonary hypertension and chronic transplant arteriopathy. Proof of principle has been shown in experiments with antibodies to platelet-derived growth factor (PDGF) receptors that cause neointimal regression in baboon polytetrafluoroethylene (PTFE) grafts and with angiotensin-converting enzyme inhibitors that induce medial atrophy in hypertensive arteries. Possible molecular targets could include PDGF receptors, A20, and BMP4. Further studies are needed to determine the utility of such a therapeutic approach to vascular disease.

Effects of angiotensin-converting enzyme inhibitors or an angiotensin receptor blocker in combination with aspirin and cilostazol on in-stent restenosis

It remains to be determined whether adding an angiotensin-converting enzyme inhibitor (ACEI) or an angiotensin II receptor blocker (ARB) to antiplatelet therapy has a therapeutic benefit on in-stent restenosis. After successful coronary stenting, 165 patients (167 lesions) were randomly assigned to a basal (aspirin 162 mg + cilostazol 200 mg/day), ACEI (basal treatment + quinapril 10 mg or perindopril 4 mg/day), or ARB (basal treatment + losartan 50 mg/day) treatment group. Quantitative coronary angiography was performed before, immediately following, and 6 months after stenting. Follow-up coronary angiography was completed in 126 patients (128 lesions). Restenosis rates tended to be higher (12, 26, and 12% for the basal, ACEI, and ARB groups, respectively), and target lesion revascularization rates were higher in the ACEI group than in the other groups (9, 23,* and 5%, respectively, *P < 0.05 versus basal group). Moreover, late lumen loss was higher in the ACEI group than in the basal group (0.60 +/- 0.55, 0.98 +/- 0.61* and 0.73 +/- 0.64 mm in the basal, ACEI, and ARB groups, respectively). The combinations of an ACEI or ARB with aspirin and cilostazol are ineffective for the prevention of in-stent restenosis, and an ACEI may even promote intimal proliferation after stent implantation.