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

Intravascular imaging in coronary stent restenosis: Prevention, characterization, and management

Despite the introduction of drug-eluting stents to combat the neointimal hyperplasia that occurred after BMS implantation, in-stent restenosis is still encountered in a significant number of patients, particularly as increasingly complex lesions are tackled by percutaneous coronary intervention. Many biological and mechanical factors interplay to produce restenosis, some of which are avoidable. Intravascular imaging provided unique insights into various forms of stent-related mechanical issues that contribute to this phenomenon. From a practical perspective, intravascular imaging can therefore help to optimize the stenting procedure to avert these issues. Moreover, once the problem of restenosis eventuates, imaging can guide the management by tackling the underlying identified mechanism. Finally, it can be used to evaluate the re-intervention results. Nevertheless, with the emergence of different treatment options, more evidence is needed to define patient/lesion-specific characteristics that may help to tailor treatment selection in a way that improves clinical outcomes.

Coronary In-Stent Restenosis: JACC State-of-the-Art Review

The introduction and subsequent iterations of drug-eluting stent technologies have substantially improved the efficacy and safety of percutaneous coronary interventions. However, the incidence of in-stent restenosis (ISR) and the resultant need for repeated revascularization still occur at a rate of 1%-2% per year. Given that millions of drug-eluting stents are implanted each year around the globe, ISR can be considered as a pathologic entity of public health significance. The mechanisms of ISR are multifactorial. Since the first description of the angiographic patterns of ISR, the advent of intracoronary imaging has further elucidated the mechanisms and patterns of ISR. The armamentarium and treatment strategies of ISR have also evolved over time. Currently, an individualized approach using intracoronary imaging to characterize the underlying substrate of ISR is recommended. In this paper, we comprehensively reviewed the incidence, mechanisms, and imaging characterization of ISR and propose a contemporary treatment algorithm.

Intravascular ultrasound versus angiography-guided drug-eluting stent implantation in patients with complex coronary lesions: An updated meta-analysis of nine randomized clinical trials

Objective:

Intravascular ultrasound (IVUS) is not routinely performed in the real-world practice, and the benefits of IVUS-guided drug-eluting stent (DES) implantation in patients with complex coronary lesions remains unclear. This updated meta-analysis attempts to evaluate the clinical outcomes of the IVUS guidance in these patients.

Methods:

We searched potential eligible citations from the PubMed, EMBASE, Medline, and other internet sources. The primary endpoint were major adverse cardiovascular events (MACE), including cardiac death, myocardial infarction (MI), and target vessel revascularization (TVR). The risk of definite/probable stent thrombosis (ST) was chosen as the safety endpoint.

Results:

Nine randomized trials including a total of 3,612 patients with complex coronary lesions were finally analyzed. Compared to angiography guidance, IVUS-guided DES implantation was associated with significantly lower incidence of MACE [odds ratios (OR) 0.57, 95% confidence intervals (CI): 0.45–0.72, p<0.001; I²=0.0%, p=0.674], cardiac death (OR 0.42, 95%CI:0.21–0.82, p=0.010; I²=0.0%, p=0.961), MI (OR 0.65, 95%CI:0.44–0.95, p=0.027; I²=41.8%, p=0.089), TVR (OR 0.55, 95%CI:0.38–0.79, p=0.001; I²=0.0%, p=0.916), target lesion revascularization (TLR) (OR 0.58, 95%CI:0.41–0.82, p=0.002; I²=0.0%, p=0.888), and ST (OR 0.48, 95%CI:0.24–0.93, p=0.029; I²=0.0%, p=0.733).

Conclusion:

The updated meta-analysis demonstrates that DES implantation under IVUS guidance leads to a significant reduction in MACE, cardiac death, MI, TVR, TLR, and ST among patients with complex coronary lesions.

Intravascular ultrasound-guided drug-eluting stent implantation for patients with unprotected left main coronary artery lesions: A single-center randomized trial

Objective:

Intravascular ultrasound (IVUS) has developed as a preferable choice for optimizing the stenting procedures mainly because it will have good access to vessel size, lesion length, or severity accurately. However, it still remains unclear about the benefits of IVUS guidance in drug-eluting stent (DES) implantation for patients with unprotected left main coronary artery (ULMCA) stenosis. The aim of the present study was to evaluate the clinical outcomes with respect to IVUS-guided DES implantation for these patients.

Methods:

A total of 336 consecutive patients from December 2010 to December 2015 were enrolled in the study. The patients were then randomly assigned into two groups: IVUS-guided group (n=167) and control group (n=169). The primary endpoint was the incidence of composite major adverse cardiac events (MACEs), including cardiac death, myocardial infarction (MI), and target vessel revascularization (TVR). The risk of stent thrombosis (ST) was chosen as the safety endpoint.

Results:

After a 1-year follow-up, the occurrence of composite MACE in the IVUS-guided group was significantly lower than that in the control group (13.2% vs. 21.9%, p=0.031), which might mainly result from the significant reduction in the risk of cardiac death (1.8% vs. 5.9%, p=0.048). Dramatically, the risk of MI did not differ significantly between the two groups (11.4% vs. 13.6%, p=0.478), though a tended reduction in TVR was observed under IVUS guidance (4.2% vs. 8.9%, p=0.068). There was no statistical significance between the two groups with respect to the risk of target lesion revascularization (IVUS-guided vs. control: 1.2% vs. 3.0%, p=0.239) and ST (IVUS-guided vs. control: 1.2% vs. 3.0%, p=0.246).

Conclusion:

The possible feasibility of IVUS-guided DES implantation for patients with ULMCA stenosis was supported by the present study. Larger and more powerful randomized trials were still warranted to research the whole benefits of IVUS guidance for these patients.

Daily risk of adverse outcomes in patients undergoing complex lesions revascularization: A subgroup analysis from the RAIN-CARDIOGROUP VII study (veRy thin stents for patients with left mAIn or bifurcatioN in real life)

INTRODUCTION

Percutaneous coronary intervention (PCI) for complex lesions, including unprotected left main (ULM) and bifurcations, is gaining a relevant role in treating coronary artery disease with good outcomes, also thanks to new generation stents. The daily risk of adverse cardiovascular events and their temporal distribution after these procedures is not known.

METHODS

All consecutive patients presenting with a critical lesion of ULM or bifurcation treated with very thin struts stents, enrolled in the RAIN-Cardiogroup VII study, were analyzed. The daily risk of major acute cardiovascular events (MACE), target lesion revascularization (TLR) and stent thrombosis (ST) and their temporal distribution in the first year of follow-up was the primary endpoint. Differences among subgroups (ULM, patient presentation, kind of stent polymer) were the secondary endpoint.

RESULTS

2745 patients were included, mean age 68 ± 11 years, 33.3% diabetics, 54.5% had an acute coronary syndrome (ACS); 88.5% of treated lesions were bifurcations, 27.2% ULM. Average daily risk was 0.022% for MACE, 0.005% for TLR and 0.004% for ST, in the first year. Bimodal distribution of adverse events, especially TLR, with an early peak in the first 50 days and a late one after 150 days, was observed. Patients with ULM presented a significantly higher daily risk of events, and ACS patients presented higher MACE risk. No difference emerged according to the type of stent polymer.

CONCLUSIONS

The daily risk of adverse events in the first year after complex PCI in our study is acceptably low. PCI on ULM carries a higher risk of complications.

Imaging during percutaneous coronary intervention for optimizing outcomes

Angiography is the current gold standard for imaging during percutaneous coronary interventions but has significant limitations. Catheter-based intravascular imaging techniques such as intravascular ultrasound and the more recent optical coherence tomography have the potential to overcome these limitations and thus optimize clinical outcomes. In this update, we discussed the current applications of the available imaging techniques, existing evidence, continuing unmet needs, and potential areas for further research.

The Current State of Left Main Percutaneous Coronary Intervention

PURPOSE OF REVIEW

While coronary artery bypass grafting (CABG) remains the standard of care, advances in stenting technology and procedural technique are changing the role of percutaneous coronary intervention (PCI) in the treatment of severe left main coronary artery (LMCA) disease. We review contemporary evidence comparing PCI and CABG for the treatment of severe LMCA disease, discuss optimal techniques during left main PCI, and provide guidance on studied revascularization strategies within specific patient subgroups.

RECENT FINDINGS

Results from randomized control trials of patients treated with PCI or CABG for severe LMCA disease demonstrate comparable short- and mid-term rates of death, myocardial infarction (MI), and stroke, but increased rates of repeat or target-vessel revascularization after PCI. Though extended follow-up data has suggested lower long-term rates of MI and stroke in patients with severe LMCA disease treated with CABG, results from patients undergoing PCI with second-generation drug-eluting stents (DES) demonstrate non-inferiority in these outcomes. These findings are generalizable to patients with severe LMCA disease having low to intermediate anatomic complexity. Intravascular ultrasound and double kissing (DK) crush stenting also reduce adverse event rates among patients undergoing left main PCI and improve long-term outcomes. In patients with severe LMCA disease having low to intermediate anatomic complexity, both CABG and PCI with second-generation DES are effective methods of revascularization with comparable long-term rates of death, MI, and stroke. The roles of multi-vessel coronary artery disease and anatomic complexity on long-term outcomes after CABG or PCI for severe LMCA disease remain under investigation.

Three-Year Major Clinical Outcomes of Angiography-Guided Single Stenting Technique in Non-Complex Left Main Coronary Artery Diseases

There is limited long-term comparative clinical outcome data concerning angiography- versus intravascular ultrasound (IVUS)-guided percutaneous coronary intervention (PCI) in non-complex left main coronary artery (LMCA) disease treated with the single stenting technique in the drug-eluting stent (DES) era.The aim of this study was to investigate whether angiography-guided stenting is comparable to IVUS-guided stenting during 3-year clinical follow-up periods in patients with non-complex LM disease treated with the single stenting technique.A total of 196 patients treated with either angiography-guided (n = 74) or IVUS-guided (n = 122) PCI were included. The primary outcome was the occurrence of major adverse cardiac events (MACE) defined as total death, non-fatal myocardial infarction (MI), target lesion revascularization (TLR), target vessel revascularization (TVR), and non-target vessel revascularization (Non-TVR). To adjust for any potential confounders, propensity score (PS) adjusted analysis was performed.During 3-year follow-up, the PS adjusted Cox-proportional hazard ratio (HR) was not significantly different between the two groups for total death, cardiac death, and MI. Also, TLR and the combined rates of TVR and non-TVR were not significantly different. Finally, MACE was not significantly different between the two groups (HR: 0.63, 95% Confidence interval (CI): 0.33-1.17; P = 0.149).Angiography-guided PCI for non-complex LMCA diseases treated with the single stenting technique showed comparable results compared with IVUS-guided PCI in reducing clinical events during 3-year clinical follow-up in the DES era. Although IVUS guided PCI is the ideal strategy, angiography-guided PCI can be an option for LMCA PCI in some selected cases.

Pathology of Endovascular Stents

Contemporary endovascular stents are the product of an iterative design and development process that leverages evolving concepts in vascular biology and engineering. This article reviews how insights into vascular pathophysiology, materials science, and design mechanics drive stent design and explain modes of stent failure. Current knowledge of pathologic processes is providing a more complete picture of the factors mediating stent failure. Further evolution of endovascular stents includes bioresorbable platforms tailored to treat plaques acutely and to then disappear after lesion pacification. Ongoing refinement of stent technology will continue to require insights from pathology to understand adverse events, refine clinical protocols, and drive innovation.

Ten-year clinical outcomes after sirolimus-eluting stent implantation: Impact of an in-stent restenosis target lesion

Little is known about the long-term outcomes after first-generation sirolimus-eluting stent (SES) implantation. We aimed to investigate the clinical outcomes up to 10 years after SES implantation.

METHODS

The study population comprised 342 patients (504 lesions) who underwent SES implantation between January 2002 and December 2004. The median duration of follow-up was 3816 days (interquartile range [Q1-Q3], 3,705-3,883 days).

RESULTS

The cumulative event rate of definite stent thrombosis was 3.9%. The cumulative rate of target lesion revascularization (TLR) at 1, 5, and 10 years was 8.7%, 18.8%, and 31.1%, respectively, and the annual rate of TLR was 3.1%. Clinically driven TLR occurred at relatively constant rate during 10 years (2.0% per year). In a multivariate analysis, higher body mass index, hemodialysis, in-stent restenosis (ISR) target lesion, and total stent length >30 mm were independent risk factors of TLR within 5 years. An independent risk factor of TLR beyond 5 years was ISR target lesion.

CONCLUSIONS

Late TLR after SES implantation is a long-term hazard, lasting up to 10 years. The ISR target lesion is a risk factor of TLR during 10 years.

Comparison of one-year clinical outcomes between intravascular ultrasound-guided versus angiography-guided implantation of drug-eluting stents for left main lesions: a single-center analysis of a 1,016-patient cohort

BACKGROUND

The importance of intravascular ultrasound (IVUS)-guided stenting of the unprotected left main coronary artery (ULMCA) remains controversial and has not been fully studied in the subset of patients with ULMCA. This study evaluated the clinical outcome of IVUS-guided stenting using a drug-eluting stent for ULMCA.

METHODS

A total of 1,016 consecutive patients with ULMCA stenosis who underwent drug-eluting stent implantation from January 2006 to December 2011 were prospectively registered. The primary endpoint of this nonrandomized registry was the rate of one-year major adverse cardiac events (MACE, including cardiac death, myocardial infarction, and target vessel revascularization). Stent thrombosis served as the safety endpoint. Propensity score matching was used to calculate the adjusted event rate.

RESULTS

The unadjusted one-year MACE rate was 14.8% in the IVUS-guided group (n=337, 33.2%), significantly different from the 27.7% (P<0.001) in the angiography-guided group (n=679, 66.8%). After propensity score matching, 291 paired patients were matched between the two groups, and the difference in one-year MACE between IVUS-guided (16.2%) versus angiography-guided (24.4%) groups was still significant (P=0.014), mainly driven by decreased rates of cardiac death (1.7%) and target vessel revascularization (3.4%) in the IVUS-guided group when compared with 5.2% (P=0.023) and 10.0% (P=0.002) in the angiography-guided group, respectively. Although it did not reach significance (P=0.075), the adjusted one-year rate of stent thrombosis in the angiography-guided group was higher than in the IVUS-guided group.

CONCLUSION

Compared with angiography guidance, IVUS-guided treatment of ULMCA using a drug-eluting stent was associated with a significant reduction of one-year cardiac death and target vessel revascularization, resulting in less frequent one-year MACE after propensity score matching.

Angioplasty guided by intravascular ultrasound: meta-analysis of randomized clinical trials

BACKGROUND

The impact of intravascular ultrasound (IVUS) use on stenting has shown inconclusive results.

OBJECTIVE

Systematic review and meta-analysis of the impact of IVUS on stenting regarding the clinical and angiographic evolution.

METHODS

A search was performed in Medline/Pubmed, CENTRAL, Embase, Lilacs, Scopus and Web of Science databases. It included randomized clinical trials (RCTs) that evaluated the implantation of stents guided by IVUS, compared with those using angiography alone (ANGIO). The minimum follow-up duration was six months and the following outcomes were assessed: thrombosis, mortality, myocardial infarction, percutaneous and surgical revascularization, major adverse cardiovascular events (MACE) and restenosis. The binary outcomes were presented considering the number of events in each group; the estimates were generated by a random effects model, considering Mantel-Haenszel statistics as weighting agent and magnitude of effect for the relative risk (RR) with its respective 95% confidence interval (95%CI). Higgins I² test was used to quantify the consistency between the results of each study.

RESULTS

A total of 2,689 articles were evaluated, including 8 RCTs. There was a 27% reduction in angiographic restenosis (RR: 0.73, 95% CI: 0.54-0.97, I² = 51%) and statistically significant reduction in the rates of percutaneous revascularization and overall (RR: 0.88; 95% CI: 0.51 to 1.53, I² = 61%, RR: 0.73, 95% CI: 0.54 to 0.99, I² = 55%), with no statistical difference in surgical revascularization (RR: 0.95, 95% CI: 0.52-1.74, I² = 0%) in favor of IVUS vs. ANGIO. There were no differences regarding the other outcomes in the comparison between the two strategies.

CONCLUSION

Angioplasty with stenting guided by IVUS decreases the rates of restenosis and revascularization, with no impact on MACE, acute myocardial infarction, mortality or thrombosis outcomes.

A prospective, randomized trial of intravascular-ultrasound guided compared to angiography guided stent implantation in complex coronary lesions: the AVIO trial

BACKGROUND

No randomized studies have thus far evaluated intravascular ultrasound (IVUS) guidance in the drug-eluting stent (DES) era. The aim was to evaluate if IVUS optimized DES implantation was superior to angiographic guidance alone in complex lesions.

METHODS

Randomized, multicentre, international, open label, investigator-driven study evaluating IVUS vs angiographically guided DES implantation in patients with complex lesions (defined as bifurcations, long lesions, chronic total occlusions or small vessels). Primary study endpoint was post-procedure in lesion minimal lumen diameter. Secondary end points were combined major adverse cardiac events (MACE), target lesion revascularization, target vessel revascularization, myocardial infarction (MI), and stent thrombosis at 1, 6, 9, 12, and 24 months.

RESULTS

The study included 284 patients. No significant differences were observed in baseline characteristics. The primary study end point showed a statistically significant difference in favor of the IVUS group (2.70 mm ± 0.46 mm vs. 2.51 ± 0.46 mm; P = .0002). During hospitalization, no patient died, had repeated revascularization, or a Q-wave MI. No difference was observed in the occurrence of non-Q wave MI (6.3% in IVUS vs. 7.0% in angio-guided group). At 24-months clinical follow-up, no differences were still observed in cumulative MACE (16.9%vs. 23.2 %), cardiac death (0%vs. 1.4%), MI (7.0%vs. 8.5%), target lesion revascularization (9.2% vs. 11.9%) or target vessel revascularization (9.8% vs. 15.5%), respectively in the IVUS vs. angio-guided groups. In total, only one definite subacute stent thrombosis occurred in the IVUS group.

CONCLUSIONS

A benefit of IVUS optimized DES implantation was observed in complex lesions in the post-procedure minimal lumen diameter. No statistically significant difference was found in MACE up to 24 months.

Assessment of drug-eluting stents and bioresorbable stents by grayscale IVUS and IVUS-based imaging modalities

Grayscale IVUS and IVUS-based imaging modalities during the last years have become useful in the assessment not only of drug eluting stent, but also of new bioresorbable vascular scaffolds. Although IVUS resolution is not sufficient for determining stent coverage (optical coherence tomography is the gold standard), serial IVUS can measure intimal hyperplasia, assess acute and late incomplete stent apposition, detect the presence and persistence of edge dissections, study edge effects and look for causes of restenosis and thrombosis. In addition other IVUS-based imaging modalities, such as IVUS-VH, iMAP or palpography, can be used to study the serial compositional and mechanical changes of the plaque behind stent struts and also to follow the bioresorption of the new bioresorbable scaffolds, analyzing the backscattering signal coming from the polymeric struts. This review details and evaluates grayscale IVUS and IVUS-based techniques findings in clinical trials, highlighting the usefulness of these imaging modalities in the study of drug eluting stents and bioresorbable vascular scaffold.

In-stent restenosis in the drug-eluting stent era

The introduction of the drug-eluting stent (DES) proved to be an important step forward in reducing rates of restenosis and target lesion revascularization after percutaneous coronary intervention. However, the rapid implementation of DES in standard practice and expansion of the indications for percutaneous coronary intervention to high-risk patients and complex lesions also introduced a new problem: DES in-stent restenosis (ISR), which occurs in 3% to 20% of patients, depending on patient and lesion characteristics and DES type. The clinical presentation of DES ISR is usually recurrent angina, but some patients present with acute coronary syndrome. Mechanisms of DES ISR can be biological, mechanical, and technical, and its pattern is predominantly focal. Intravascular imaging can assist in defining the mechanism and selecting treatment modalities. Based upon the current available evidence, an algorithm for the treatment approaches to DES restenosis is proposed.

Titanium nitride oxide coating on rough titanium stimulates the proliferation of human primary osteoblasts

OBJECTIVES

Titanium is widely used in contemporary endosseous implantology and there is considerable thrust to further promote osseointegration by implant surface modifications. The aim of this study was to evaluate the effect of a titanium-nitride-oxide (TiNOx) coating on commercially pure microroughened titanium by assessing the proliferation and differentiation of human primary osteoblasts.

MATERIALS AND METHODS

Cell proliferation, gene expression, alkaline phosphatase activity, osteoprotegerin and osteocalcin secretion were analyzed for a time course of 3 weeks, with or without additional stimulation by 1.25(OH)(2) vitamin D(3) 100 nM.

RESULTS

A 1.5-fold increase in the proliferation rate of cells grown on TiNOx-coated titanium as compared with uncoated surfaces was observed. SEM views indicated that the cells' normal morphology with their numerous extensions was maintained. The differentiation process on the TiNOx surface was only affected to a minor degree and translated into a slight delay in osteoblast maturation when compared to uncoated titanium.

CONCLUSION

Pending confirmation of these results in vivo, TiNOx coatings could potentially accelerate and enhance osseointegration.

Main branch stent deformation following difficult side branch rewiring and balloon dilatation. Rare complication of provisional T stenting

Coronary artery bifurcations are one of the largest challenges in interventional cardiology. Presented is the case of a patient in whom restenosis of a drug-eluting stent (DES) occurred as a consequence of guide wire re-crossing between the main vessel stent struts and the vessel wall in the proximal part of DES, and consequential balloon crushing of the proximal portion of the DES. Initially, the complication was not recognized because of a good angiographic result and absence of intravascular ultrasound (IVUS) guidance during the procedure. During the second procedure, IVUS analysis explained the mechanism of the DES failure. The problem was solved with the implantation of a new DES.

Defining a new standard for IVUS optimized drug eluting stent implantation: the PRAVIO study

OBJECTIVES

Preliminary Investigation to the Angiographic Versus IVUS Optimization Trial is a single center prospective observational intravascular ultrasound (IVUS) guided stent implantation study assessing new criteria for optimal drug eluting stent (DES) deployment.

BACKGROUND

IVUS assessment of DES often reveals underexpansion and malapposition. Optimal stent deployment is currently poorly defined and previous criteria may not be suitable in long and complex lesions.

METHODS

Optimization was defined as achieving >/or 70% of the cross-sectional area (CSA) of the postdilation balloon. This criterion was applied in 113 complex lesions. The size of this balloon was calculated according to vessel media-to-media diameters at various sites inside the stented segment. The IVUS guided treated lesions were matched according to diabetes, vessel type, reference vessel diameter, minimum lumen diameter (MLD), and lesion length with a group of angiographic treated lesions to compare final MLD achieved.

RESULTS

Mean minimum stent CSA according to the postdilation balloon utilized was 4.62 mm(2), 6.26 mm(2), 7.87 mm(2), and 9.87 mm(2) for 2.5 mm, 3.0 mm, 3.5 mm, and 4 mm balloons, respectively. Final MLD (mm) was significantly larger in the IVUS compared to the angiographic-guided group (3.09 +/- 0.50 vs. 2.67 +/- 0.54; P < 0.0001). There were no procedural complications related to IVUS use.

CONCLUSIONS

We propose new IVUS criteria based on vessel remodeling that results in an increment in the final MLD, compared to angiographic guidance, which is much larger than any previously published study. This criterion seems to be safely achievable. A proposed randomized study (angiographic vs. IVUS optimization trial) has been launched to test these concepts.

Relation of drug-eluting stent strut distribution to stent thrombosis in coronary arteries

The distribution of stent struts is critical to drug deposition and, therefore, may affect the amount of neointima and the risk of thrombosis after drug-eluting stent (DES) implantation. The aim of our study was to evaluate stent strut distribution in the setting of a drug-eluting stent thrombosis (ST). We retrospectively analyzed postprocedural intravascular ultrasound (IVUS) images of 13 patients who subsequently developed ST (14 DES thrombotic lesions) and a control group of 27 patients (30 DES lesions) matched for stent type and presence of chronic renal failure. In addition to standard IVUS measurements, visible struts were counted and maximum interstrut angle was measured at 1-mm intervals. Early ST was defined as < or =30 days after DES deployment and late ST as >30 days after DES deployment. Compared with DES controls, the ST group had a larger maximum interstrut angle (60.8 +/- 8.3 degrees vs 55.7 +/- 4.8 degrees , p = 0.014) and a similar number of stent struts (8.4 +/- 0.6 vs 8.7 +/- 0.6, p = NS). Maximum interstrut angle tended to be larger in late ST than in early ST (66.1 +/- 10.8 degrees vs 57.8 +/- 5.0 degrees , p = 0.071). The incidence of maximum interstrut angles > or =90 degrees and > or =120 degrees observed continuously for > or =2 mm of stent length was higher in the ST group (p = 0.009 and p = 0.096, respectively). In conclusion, DES-treated lesions leading to ST had larger maximum interstrut gaps distributed circumferentially and longitudinally, but a similar number of struts at the time of DES implantation compared with DES controls.

Serial intravascular ultrasound analysis of peri-stent remodeling and proximal and distal edge effects after sirolimus-eluting or paclitaxel-eluting stent implantation in patients with diabetes mellitus

Patients with diabetes have an increased risk of in-stent restenosis after coronary stent implantation. Serial intravascular ultrasound was used to study chronic arterial responses and edge effects after implantation of Cypher (Cordis, Johnson & Johnson, Miami Lakes, Florida) or Taxus (Boston Scientific, Maple Grove, Minnesota) stents in diabetic patients. Seventy-four diabetic patients were randomly assigned to Cypher or Taxus stent implantation. Intravascular ultrasound of 5-mm long segments immediately proximal and distal to the stent was performed after the procedure and at the 8-month follow-up. The increase in peri-stent external elastic membrane (EEM) volume was more pronounced in the Taxus group (292.4 +/- 132.6 to 309.5 +/- 146.8 mm(3)) than in the Cypher group (274.4 +/- 137.2 to 275.4 +/- 140.1 mm(3); p = 0.005). Peri-stent plaque volume increased in the Taxus group (152.5 +/- 73.7 to 166.1 +/- 85.1 mm(3)), but was unchanged in the Cypher group (153.5 +/- 75.5 to 151.5 +/- 75.8 mm(3); p = 0.002). In proximal and distal reference segments, mean lumen area decreased within the entire 5-mm edge segment (proximal and distal) because of plaque progression (distal, 5.5 +/- 3.6 to 5.8 +/- 3.7 mm(2); p = 0.097; proximal, 8.1 +/- 2.7 to 8.7 +/- 2.9 mm(2); p = 0.006) without remodeling (change in EEM) in the Taxus group. Conversely, there were no significant changes in reference-segment EEM or plaque areas in the Cypher group. In conclusion, in diabetic patients, Taxus stent implantation was associated with increased (1) peri-stent EEM volume and peri-stent plaque, and (2) stent edge plaque progression accompanied by lumen reduction without remodeling. These findings were not seen in Cypher stents.

Intravascular ultrasound-guided percutaneous coronary interventions in contemporary practice

Intravascular ultrasound imaging has been pivotal in the understanding of coronary artery disease and the development of percutaneous coronary intervention. The ability to analyse vessel walls and measure atherosclerotic lesions more accurately has enabled the field of invasive cardiology to overcome the limits of angiography. In fact, intravascular ultrasound measurements correlate with functional measurement of coronary blood flow, as a result interest in their use for the diagnosis of lesion severity in ambiguous lesions and for left main trunk analysis has grown. On the interventional side, intravascular ultrasound is used to determine the major predictors of restenosis and stent thrombosis, which are the main pitfalls of percutaneous coronary intervention. In the bare-metal stent era, intravascular ultrasound-guided percutaneous coronary intervention was associated with a reduction in restenosis rates because it enabled identification and treatment of the risk factors for complications. Although drug-eluting stents have provided a great technological advance in percutaneous coronary intervention, further reducing the rate of in-stent restenosis, they have not abolished restenosis completely; intravascular ultrasound has also been used in this setting to identify the mechanisms responsible for drug-eluting stent restenosis. As in the bare-metal stent era, identification of the predictors of restenosis and stent thrombosis and their subsequent treatment may offer the promise of improved outcome in the drug-eluting stent era. This review focuses on the potential benefit of intravascular ultrasound-guided percutaneous coronary intervention with regard to restenosis and stent thrombosis in the bare-metal stent and drug-eluting stent eras.

Prediction of protein function and pathways in the genome era

The growing number of completely sequenced genomes adds new dimensions to the use of sequence analysis to predict protein function. Compared with the classical knowledge transfer from one protein to a similar sequence (homology-based function prediction), knowledge about the corresponding genes in other genomes (orthology-based function prediction) provides more specific information about the protein's function, while the analysis of the sequence in its genomic context (context-based function prediction) provides information about its functional context. Whereas homology-based methods predict the molecular function of a protein, genomic context methods predict the biological process in which it plays a role. These complementary approaches can be combined to elucidate complete functional networks and biochemical pathways from the genome sequence of an organism. Here we review recent advances in the field of genomic-context based methods of protein function prediction. Techniques are highlighted with examples, including an analysis that combines information from genomic-context with homology to predict a role of the RNase L inhibitor in the maturation of ribosomal RNA.