Impact of intravascular ultrasound lesion characteristics on neointimal hyperplasia following sirolimus-eluting stent implantation

Intravascular imaging of coronary calcification and its clinical implications

Calcium impacts the natural history and treatment of coronary artery disease in many ways. Intravascular imaging studies, mostly intravascular ultrasound, but more recently studies using optical coherence tomography, have been instrumental in increasing our understanding of the relationship between calcium and coronary atherosclerosis, the predictors, the natural history of this relationship, and the impact on treatment. On one hand, stable coronary lesions are associated with more calcium than unstable lesions; and the amount of calcium may affect the success of percutaneous coronary intervention. On the other hand, calcium correlates with plaque burden; unstable lesions are associated with focal calcium deposits; and calcific nodules are one of the morphologies of vulnerable plaque. This review focuses on more than 20 years of intravascular imaging studies of the relationship between calcium and coronary atherosclerosis.

Systematic review of effectiveness of oral sirolimus after bare-metal stenting of coronary arteries for prevention of in-stent restenosis

Neointimal hyperplasia after percutaneous coronary intervention is a major determinant of in-stent restenosis (ISR). Drug-eluting stents (DES) mitigate neointimal hyperplasia and thereby lead to a lower rate of ISR compared with bare-metal stents (BMS). Recent studies have demonstrated that short-term use of oral sirolimus after BMS leads to a significant reduction in ISR. We therefore sought to do a systematic review of studies to determine the angiographic and clinical benefits of early short-term use of oral sirolimus after BMS of native coronary arteries. We conducted PubMed, Embase, Cochrane database review, and Web of Science search of studies comparing oral sirolimus after BMS to BMS alone or DES. Outcomes analyzed were ISR and target lesion revascularization (TLR) as well as major adverse cardiovascular events. A total of 488 patients from 4 studies were included in the review (2006 to 2010). Three studies, comparing BMS alone versus BMS plus oral sirolimus, demonstrated significant reduction in ISR in the oral sirolimus group. Two of these studies also demonstrated significant reduction in TLR at 6-12 month follow-up. The fourth study comparing BMS plus oral sirolimus versus DES showed a lower but nonsignificant reduction in TLR in addition to significant cost saving in the group treated with oral sirolimus. In conclusion, our systematic review demonstrates that early short-term systemic use of sirolimus after BMS resulted in a significant reduction in ISR and TLR. In addition, ISR rates were comparable to DES with the added benefit of cost saving.

Culprit lesion remodelling and long-term prognosis in patients with acute coronary syndrome: an intravascular ultrasound study

AIMS

Positive arterial remodelling is recognized as one of the morphological characteristics of the vulnerable plaque. Limited data are available on a long-term outcome of acute coronary syndrome (ACS) patients with culprit lesion positive arterial remodelling (PR). The aim of this study was to investigate the long-term impact of culprit lesion PR in patients with ACS.

METHODS AND RESULTS

In 134 patients with ACS, intravascular ultrasound (IVUS) was performed to assess target lesion remodelling before percutaneous coronary intervention. PR was defined as the ratio of the external elastic membrane cross-sectional area at the target lesion to that of at the proximal reference of >1.05, and intermediate or negative remodelling (IR/NR) was defined as that of ≤1.05. Major adverse cardiac event (MACE) was defined as a composite of death, ACS, and target lesion revascularization. During the follow-up (median 5.8 years), MACE-free survival was significantly lower in the PR group than that in the IR/NR group (log-rank, P = 0.005). Survival and ACS-free survival were also significantly lower in the PR group than that in the IR/NR group (log-rank, both P = 0.04). By multivariable Cox regression analysis, PR (hazard ratio = 2.4, P = 0.02) and diabetes (hazard ratio = 1.9, P = 0.03) were independent predictors of MACE.

CONCLUSION

Culprit lesion PR was associated with a poor long-term prognosis in patients with ACS. PR may be a marker of vulnerable patients.

Features and parameters of drug-eluting stent deployment discoverable by intravascular ultrasound

The only routinely available tool for assessing many features of stent implantation, intravascular ultrasound (IVUS) has become indispensable in trials of drug-eluting stents (DESs) and is currently the best way to identify or exclude causes of DES failure. Although IVUS resolution is not sufficient for determining reendothelialization, serial (postprocedure and follow-up) IVUS can measure intimal hyperplasia (IH), assess acute and late incomplete stent apposition, detect the presence and persistence of edge dissections, assess vascular responses such as remodeling, study edge effects, compare overlapping with nonoverlapping segments, and look for causes of restenosis and thrombosis. Percentage IH volume is one IVUS measure of efficacy that has been routinely assessed and compared in studies of DESs; IH volume and external elastic membrane, luminal, and stent cross-sectional area are others. This review details and evaluates IVUS findings in the important clinical trials conducted with the first-generation DESs: a sirolimus-eluting stent, a polymeric paclitaxel-eluting stent, and a nonpolymeric paclitaxel-eluting stent. IVUS results apparent in DES failure (restenosis and thrombosis) are also examined.

Randomized Comparison of Sirolimus and Paclitaxel Drug-Eluting Stents for Long Lesions in the Left Anterior Descending Artery

OBJECTIVES

The goal of this work was to verify whether the superiority of the sirolimus-eluting stent (SES) in inhibiting neointimal hyperplasia could be demonstrated in complex coronary lesions.

BACKGROUND

Both the SES (Cypher, Cordis, Miami Lakes, Florida) and the paclitaxel-eluting stent (PES) (Taxus, Boston Scientific, Natick, Massachusetts) have shown a marked reduction in neointimal hyperplasia compared with bare-metal stents. Intravascular ultrasound (IVUS) is the best method to assess arterial response to stent deployment, but few IVUS data are available comparing complex lesions treated with SES or PES.

METHODS

We prospectively randomized patients with complex lesions to SES or PES implantation. Intravascular ultrasound and quantitative angiography were performed post-procedure and at 9 months. Mean neointimal hyperplasia area (NIHA), percent of NIHA (NIHA%), mean peristent plaque area (PSPA), and percent of PSPA (PSPA%) were calculated. The primary end point was NIHA% at follow-up. Secondary end points included change in PSPA% and angiographic late luminal loss at follow-up.

RESULTS

Of the 100 patients enrolled, 42 receiving the SES and 43 receiving the PES had adequate IVUS assessment. Vessel, plaque, and lumen areas were comparable at follow-up, but NIHA% was significantly lower with SES than PES (7.4 +/- 4.2% vs. 15.4 +/- 8.1%; p < 0.001). A significant reduction in PSPA% was observed with SES (-4 +/- 10% vs. 0 +/- 8%; p = 0.01). Late loss was significantly lower with SES (0.16 +/- 0.19 mm vs. 0.32 +/- 0.33 mm; p = 0.003).

CONCLUSIONS

The SES shows a significantly higher inhibition of neointimal hyperplasia compared with PES in complex lesions. However, both stents have excellent IVUS and angiographic results at 9 months. A significant reduction in peri-stent plaque is observed only with SES.

Initial and Long-Term Outcomes of Sirolimus-Eluting Stents for Calcified Lesions Compared With Bare-Metal Stents

The aim of this study was to compare the initial and long-term outcomes of sirolimus-eluting stents (SES) and bare-metal stents (BMS) in patients with calcified lesions without performing rotational atherectomy. The subjects were 79 consecutive lesions (38 in the SES group and 41 in the BMS group) which were confirmed to have superficially calcified lesions by intravascular ultrasound. In all lesions, the stent was implanted after predilatation with a balloon. The patient characteristics were not different between the 2 groups. All procedures were successfully performed in both groups. Vessel area was significantly smaller in the SES group than in the BMS group (11.01 +/- 3.88 mm(2) versus 13.08 +/- 3.49 mm(2), P < 0.005), as was the lumen area (5.41 +/- 2.31mm(2) versus 6.48 +/- 2.04 mm(2), P < 0.005). Minimum stent area was significantly smaller in the SES group than in the BMS group (5.61 +/- 1.54 mm(2) versus 6.69 +/- 1.74 mm(2), P < 0.01). In cases in whom angiographic follow-ups were performed, the late loss was significantly smaller in the SES group than in the BMS group (0.19 +/- 0.49 mm versus 0.76 +/- 0.48 mm, P < 0.001). The restenosis rate was significantly lower in the SES group than in the BMS group (8.8% versus 33.3%, P < 0.05) and the TLR rate tended to be lower in the SES group (7.9% versus 19.5%). Stent thrombosis was not observed in either group. The results suggest that SES are more effective than BMS and can be used safely when treating calcified lesions if predilatation with a balloon is possible.

Intravascular ultrasound in the drug-eluting stent era

Intravascular ultrasound (IVUS) has become an indispensable part of all drug-eluting stent (DES) studies; findings must be put into context with the IVUS findings in bare metal stents. Unfortunately, there is not yet a complete picture of either the Cypher (Cordis, Miami, Florida) or the Taxus (Boston Scientific, Maple Grove, Minnesota) stent (the two U.S. Food and Drug Administration-approved devices). Intimal hyperplasia volume in DES is reduced to <15% of stent volume, but stent underexpansion continues to be a consistent finding in DES failures (restenosis and thrombosis). The utility of IVUS to assure adequate stent expansion may be more important whenever there are clinical risk factors for DES failure.