Thrombosis of Second-Generation Drug-Eluting Stents in Real Practice

Revolutionizing Cardiovascular Frontiers: A Dive Into Cutting-Edge Innovations in Coronary Stent Technology

Plain balloon angioplasty was the initial method used to enlarge the intracoronary lumen size. However, it was linked to acute coronary closure due to early vessel recoil. This led to the invention of coronary stents, which offer mechanical support to open and maintain the vascular lumen. Nevertheless, the metallic scaffold introduced other issues, such as thrombosis and restenosis caused by neointimal proliferation. To address these concerns, polymers were employed to cover the scaffold, acting as drug reservoirs and regulators for controlled drug release. The use of polymers prevents direct contact between blood and metallic scaffolds. Drugs within the stent were incorporated to inhibit proliferation and expedite endothelialization in the healing process. Despite these advancements, adverse effects still arise due to the inflammatory reaction caused by the polymer material. Consequently, resorbable polymers and scaffolds were later discovered, but they have limitations and are not universally applicable. Various scaffold designs, thicknesses, materials, polymer components, and drugs have their own advantages and complications. Each stent generation has been designed to address the shortcomings of the preceding generation, yet new challenges continue to emerge. Conflicting data regarding the long-term safety and efficacy of coronary stents, especially in the extended follow-up, further complicates the assessment.

Applying DESyne coronary stent system in patients with ischemic heart disease: experience from Jordan

Background

The safety and efficacy of drug-eluting coronary stenting have been established for various degrees of severity of coronary artery disease. The DESyne is a contemporary cobalt-chromium thin-strut stent which has been studied in low-risk patients so far.

Aim

The aim of this study was to evaluate the safety, efficacy and performance of the DESyne stent in patients with an indication for coronary stent implantation at the King Abdullah University Hospital (KAUH), Jordan.

Patients and methods

Hospital records for all patients implanted with DESyne stent were retrospectively reviewed. Specific clinical events were recorded for all cases, and their incidence rates were estimated by the Kaplan-Meier method. A total of 715 patients (79.3% males and 58.3% with diabetes) with a mean age of 57.8±10.3 years were enrolled in this study. An acute coronary syndrome was the most frequent indication for stenting in 86.3% of the patients (unstable angina 72.0%, myocardial infarction [MI] 14.3%). A total of 849 lesions (1.2 lesions/patient) were treated with the DESyne stent.

Results

After 1 year of follow-up, the death rates from cardiac or noncardiac causes were 0.6% and 1.1%, respectively. MI was observed in 0.9% of the cases, and an ischemia-driven revascularization was performed in 0.8% of them. The definite/probable stent thrombosis rate was 1.1%.

Conclusion

Favorable clinical event rates including cardiac death, MI and stent thrombosis were observed for the DESyne stent in ischemic heart patients especially those with high prevalence of diabetes mellitus and acute coronary syndrome.

Annual Incidence of Confirmed Stent Thrombosis and Clinical Predictors in Patients With ACS Treated With Ticagrelor or Prasugrel

INTRODUCTION AND OBJECTIVES

There is little evidence on rates of stent thrombosis (ST) in patients receiving dual antiplatelet therapy (DAPT) with ticagrelor or prasugrel. The aim of this study was to analyze the incidence and predictors of ST after an acute coronary syndrome among patients receiving DAPT with ticagrelor vs prasugrel.

METHODS

We used data from the RENAMI registry (REgistry of New Antiplatelet therapy in patients with acute Myocardial Infarction), analyzing a total of 4123 acute coronary syndrome patients discharged with DAPT with ticagrelor or prasugrel in 11 centers in 6 European countries. The endpoint was definite ST within the first year. A competitive risk analysis was carried out using a Fine and Gray regression model, with death being the competitive event.

RESULTS

A total of 2604 patients received DAPT with ticagrelor and 1519 with prasugrel; ST occurred in 41 patients (1.10%), with a similar cumulative incidence between ticagrelor (1.21%) and prasugrel (0.90%). The independent predictors of ST were age (sHR, 1.03; 95%CI, 1.01-1.06), ST segment elevation (sHR, 2.24; 95%CI, 1.22-4.14), previous myocardial infarction (sHR, 2.56; 95%CI, 1.19-5.49), and serum creatinine (sHR, 1.29; 95%CI, 1.08-1.54).

CONCLUSIONS

Stent thrombosis is infrequent in patients receiving DAPT with ticagrelor or prasugrel. The variables associated with an increased risk of ST were advanced age, ST segment elevation, previous myocardial infarction, and serum creatinine.

Safety and Efficacy of New Biodegradable Polymer-based Sirolimus-Eluting Stents in a Preclinical Model

INTRODUCTION AND OBJECTIVES

New drug-eluting stents (DES) designed to overcome the limitations of existing devices should initially be tested in preclinical studies. Our objective was to analyze the safety and efficacy of new biodegradable polymer-based DES compared with bare-metal stents (BMS) and commercially available DES in a model of normal porcine coronary arteries.

METHODS

We randomly implanted 101 stents (BMS and biodegradable polymer-based sirolimus-eluting stents: 3 test stent iterations [BD1, BD2, and BD3], Orsiro, Biomime and Biomatrix) in the coronary arteries of 34 domestic pigs. Angiographic and histomorphometric studies were conducted 1 month (n = 83) and 3 months (n = 18) later.

RESULTS

The stents were implanted at a stent/artery ratio of 1.31 ± 0.21, with no significant differences between groups. At 1 month, the new test stents (BD1, BD2 and BD3) showed less late loss and angiographic restenosis, as well as lower histologic restenosis and neointimal area (P < .0005), than the BMS. There were no differences in endothelialization, vascular injury, or inflammation between the new test stents and BMS, although the new stents showed higher fibrin deposition (P = .0006). At 3 months, all these differences disappeared, except for a lower neointimal area with the new BD1 stent (P = .027). No differences at any time point were observed between the new test stents and commercially available controls.

CONCLUSIONS

In this preclinical model, the new biodegradable polymer-based DES studied showed less restenosis than BMS and no significant differences in safety or efficacy vs commercially available DES.

Outcome After Myocardial Infarction Treated With Resolute Integrity and Promus Element Stents: Insights From the DUTCH PEERS (TWENTE II) Randomized Trial

INTRODUCTION AND OBJECTIVES

In acute myocardial infarction (MI), novel highly deliverable drug-eluting stents (DES) may be particularly valuable as their flexible stent designs might reduce device-induced traumas to culprit lesions. The aim of the study was to assess the safety and efficacy of percutaneous coronary interventions with 2 novel durable polymer-coated DES in patients with acute MI.

METHODS

The prospective, randomized DUTCH PEERS (TWENTE II) multicenter trial compares Resolute Integrity and Promus Element stents in 1811 all-comer patients, of whom 817 (45.1%) were treated for ST-segment elevation MI or non-ST-segment elevation MI and the 2-year outcome is available in 99.9%. The primary clinical endpoint is target vessel failure (TVF), a composite of cardiac death, target vessel related MI, or target vessel revascularization.

RESULTS

Of all 817 patients treated for acute MI, 421 (51.5%) were treated with Resolute Integrity and 396 (48.5%) with Promus Element stents. At the 2-year follow-up, the rates of TVF (7.4% vs 6.1%; P = .45), target lesion revascularization (3.1% vs 2.8%; P = .79), and definite stent thrombosis (1.0% vs 0.5%; P = .69) were low for both stent groups. Consistent with these findings in all patients with acute MI, outcomes for the 2 DES were favorable and similar in both, with 370 patients with ST-segment elevation MI (TVF, 5.1% vs 4.9%; P = .81) and 447 patients with non-ST-segment elevation MI (TVF, 9.0% vs 7.5%; P = .56).

CONCLUSIONS

Resolute Integrity and Promus Element stents were both safe and efficacious in treating patients with acute MI. The present 2-year follow-up data underline the safety of using these devices in this particular clinical setting.

First- Versus Second-Generation Drug-Eluting Stents in Acute Coronary Syndromes (Katowice-Zabrze Registry)

Background

There are sparse data on the performance of different types of drug-eluting stents (DES) in acute and real-life setting.

Objective

The aim of the study was to compare the safety and efficacy of first- versus second-generation DES in patients with acute coronary syndromes (ACS).

Methods

This all-comer registry enrolled consecutive patients diagnosed with ACS and treated with percutaneous coronary intervention with the implantation of first- or second-generation DES in one-year follow-up. The primary efficacy endpoint was defined as major adverse cardiac and cerebrovascular event (MACCE), a composite of all-cause death, nonfatal myocardial infarction, target-vessel revascularization and stroke. The primary safety outcome was definite stent thrombosis (ST) at one year.

Results

From the total of 1916 patients enrolled into the registry, 1328 patients were diagnosed with ACS. Of them, 426 were treated with first- and 902 with second-generation DES. There was no significant difference in the incidence of MACCE between two types of DES at one year. The rate of acute and subacute ST was higher in first- vs. second-generation DES (1.6% vs. 0.1%, p < 0.001, and 1.2% vs. 0.2%, p = 0.025, respectively), but there was no difference regarding late ST (0.7% vs. 0.2%, respectively, p = 0.18) and gastrointestinal bleeding (2.1% vs. 1.1%, p = 0.21). In Cox regression, first-generation DES was an independent predictor for cumulative ST (HR 3.29 [1.30-8.31], p = 0.01).

Conclusions

In an all-comer registry of ACS, the one-year rate of MACCE was comparable in groups treated with first- and second-generation DES. The use of first-generation DES was associated with higher rates of acute and subacute ST and was an independent predictor of cumulative ST.

Spanish Cardiac Catheterization and Coronary Intervention Registry. 24th Official Report of the Spanish Society of Cardiology Working Group on Cardiac Catheterization and Interventional Cardiology (1990-2014)

INTRODUCTION AND OBJECTIVES

The Working Group on Cardiac Catheterization and Interventional Cardiology presents its annual report on the data from the registry of the activity in Spain in 2014.

METHODS

Data were voluntarily provided by participating centers. The information was introduced online and was analyzed by the Steering Committee of the Working Group on Cardiac Catheterization and Interventional Cardiology.

RESULTS

Data were reported by 106 hospitals. A total of 140 461 diagnostic procedures (125 484 coronary angiograms) were performed, representing a rate of 3014 diagnostic studies per million population. This year, the number of percutaneous coronary interventions increased to 67 611, giving a rate of 1447 interventions per million population. A total of 94 458 stents were implanted, including 64 057 drug-eluting stents and 2424 biodegradable intracoronary devices. Of the total number of percutaneous coronary interventions, 17 825 were in acute myocardial infarction, representing 26.4% of all coronary interventions. A radial approach was used in 74% of diagnostic procedures and in 70.4% of interventional procedures. The use of renal denervation decreased, whereas over 125 mitral leak closures were performed. Transcatheter aortic valve implantation procedures exceeded 1300 implantations per year, a 27% increase from 2013.

CONCLUSIONS

The registry for 2014 shows a slight increase in coronary disease activity despite no increase in the management of ST-segment elevation myocardial infarction. Drug-eluting intracoronary devices now comprise over 70% of all intracoronary devices. A continual increase is only seen in certain structural interventional techniques, such as transcatheter aortic valve implantation and perivalvular leak closure.

Validation of the Ability of SYNTAX and Clinical SYNTAX Scores to Predict Adverse Cardiovascular Events After Stent Implantation: A Systematic Review and Meta-Analysis

To compare the predicative ability of SYNTAX (Synergy between PCI with Taxus and Cardiac Surgery) and clinical SYNTAX scores for major adverse cardiac events (MACEs) after stent implantation in patients with coronary artery disease (CAD). Studies were identified by electronic and manual searches. Twenty-six studies were included in the meta-analysis. The pooled C-statistics of SYNTAX score for 1- and 5-year all-cause mortality (ACM) were 0.65 (95% confidence interval [CI]: 0.61-0.68) and 0.62 (95% CI: 0.59-0.65), respectively, with weak heterogeneity. The 1- and 5-year ACM pooled C-statistics for clinical SYNTAX scores were significantly higher at 0.77 and 0.71, respectively (Ps < .05). Both scoring systems predicted 1- and 5-year MACE equally well. The pooled risk ratio of the SYNTAX score for predicting 1-year ACM per unit was 1.04 (95% CI: 1.03-1.05). Calibration analysis indicated SYNTAX scores overestimated the risk of major adverse cardiac and cerebrovascular events in each risk stratum. The SYNTAX score demonstrated minimal discrimination in predicting 1- or 5-year adverse cardiovascular events after percutaneous coronary intervention in patients with CAD. The clinical SYNTAX score could further improve the predictive capability for ACM but not MACE.

Stent thrombosis caused by metal allergy complicated by protein S deficiency and heparin-induced thrombocytopenia: a case report and review of the literature

A 43-year-old woman recipient of a bare metal coronary stent during an acute anterior myocardial infarction was repeatedly hospitalized with recurrent stent thrombosis (ST) over the following 3 years. Emergent coronary angiography showed a thrombus in the in-stent segment of the proximal left anterior descending artery. We repeatedly aspirated the thrombus, which immediately reformed multiple times. The discontinuation of heparin and administration of thrombolytics and argatroban, followed by repeated balloon dilatations, ended the formation of new thrombi. The patient was found to be allergic to nickel, protein S deficient and carrier of heparin-induced thrombocytopenia antibody. We discuss this case in the context of a) literature pertaining to acute coronary syndromes in the young, and b) the detailed investigations needed to identify thrombotic risk factors. Steroids may be effective to prevent recurrent ST caused by stent allergy.

Dual Antiplatelet Therapy for 6 Months vs 12 Months After New-generation Drug-eluting Stent Implantation: Matched Analysis of ESTROFA-DAPT and ESTROFA-2

INTRODUCTION AND OBJECTIVES

The recommendation for dual antiplatelet therapy following drug-eluting stent implantation ranges from 6 months to 12 months or beyond. Recent trials have suggested the safety of a 6-month dual antiplatelet therapy regimen, yet certain caveats to these studies limit the applicability of this shorter duration dual antiplatelet therapy strategy in real world settings.

METHODS

A registry was constructed with consecutive recruitment of patients undergoing new-generation drug-eluting stent implantation and prescribed 6 months of dual antiplatelet therapy. Propensity score matching was undertaken with a historical cohort of patients treated with second-generation drug-eluting stents who received 12 months of dual antiplatelet therapy from the ESTROFA-2 registry. The sample size was calculated using a noninferiority basis and the primary endpoint was the combination of cardiac death, myocardial infarction, revascularization, or major bleeding at 12 months.

RESULTS

The analysis included 1286 patients in each group, with no significant differences in baseline characteristics. The primary endpoint occurred in 5.0% and 6.6% in the 6-month and 12-month groups, respectively (P = .001 for noninferiority). The incidence of definite or probable stent thrombosis was 0.5% and 0.7% in the 6-month and 12-month groups, respectively (P = .4). Major bleeding events were lower in the 6-month group than in the 12-month group (0.8% vs 1.4%; P = .2) CONCLUSIONS: In selected patients in this large multicenter study, the safety and efficacy of a 6-month dual antiplatelet therapy regimen after implantation of new-generation drug-eluting stents appeared to be noninferior to those of a 12-month dual antiplatelet therapy regimen.

2014 update on interventional cardiology

This article reviews the most relevant publications and studies in the field of interventional cardiology in 2014. In the area of coronary interventional procedures, integrated treatment of acute coronary syndrome continues to be the subject of numerous studies that evaluate different devices and pharmacological and mechanical strategies that can be used without increasing the risk of hemorrhage or the need for reintervention. Certain anatomical substrates continue to generate a considerable number of publications, both on the outcomes with different stents and on the use of specific techniques. Bioabsorbable drug-eluting stents are used in increasingly complex lesions with promising results. The development of interventional procedures for structural heart disease continues to advance, with new evidence on percutaneously placed aortic valve prostheses, the outcome of percutaneous mitral valve repair, and the safety and efficacy of left atrial appendage occlusion. Finally, renal denervation has generated one of the major debates of the year.

Comparison of paclitaxel-eluting vs. everolimus-eluting stents implanted simultaneously in different lesions of the same coronary artery: 12-month follow-up with optical coherence tomography

AIMS

Optical coherence tomography (OCT) allows a detailed assessment of intimal coverage and strut apposition which are well known substrates for late thrombosis. This study sought to assess and compare long-term coverage and apposition of PES and EES implanted in different lesions of the same coronary artery (and in the same patient).

METHODS AND RESULTS

A total of 30 patients were included. In these patients PES and EES were implanted in the same vessel in two similar lesions. The selection of the stent for each lesion was random. At 12 months, 30 PES were examined analysing 154±90 struts/stents and 30 EES analysing 158±72 struts/stents. The proportion of uncovered struts was 0.8±1.3% for EES and 1.5±2.9% for PES (p=0.3), and the proportion of malapposed struts was 1.25±2.1% and 0.98±2%, respectively (p=0.2). A pooled analysis was performed using the random effects model, given the significant heterogeneity found, which did not show significant differences between EES and PES for non-coverage (RR 0.73, 95% CI: 0.32-1.67) or malapposition (RR 1.60, 95% CI: 0.56-4.61). The presence of non-coverage in malapposed struts was 62% with PES and 15% with EES (p<0.0001), the maximal malapposition area being significantly larger with PES (0.6±0.3 vs. 0.25±0.2 mm², p=0.001).

CONCLUSIONS

In highly matched conditions, with PES and EES implanted in the same artery, both DES showed a comparable degree of intimal coverage and apposition at one-year follow-up. A smaller area of malapposition with non-covered struts was found with EES.

Approach to coronary bifurcation lesions using the everolimus-eluting stent: comparison between a simple strategy and a complex strategy with T-stenting

INTRODUCTION AND OBJECTIVES

Coronary bifurcation lesions can be approached using a simple or a complex strategy. In clinical trials with first-generation drug-eluting stents, the complex strategy was not superior to the simple approach. However, to date, the best strategy when using second-generation drug-eluting stents has not been defined.

METHODS

We performed a prospective randomized study comparing a simple vs a complex strategy involving T-stenting for the percutaneous revascularization of bifurcation lesions using the everolimus-eluting stent. Angiographic and clinical follow-up were performed at 9 months.

RESULTS

We included 70 lesions in 69 patients, who were randomized to the simple (34 lesions, 33 patients) or complex strategy (36 lesions and patients). In all, 85.6% of the lesions included were true bifurcations. The crossover rate was 17.1%. The binary restenosis rate was 12.1%, with no differences between the groups. Side branch restenosis tended to be higher with the simple strategy in the intention to treat analysis (10.7% vs 0%) but not in the per protocol analysis (5.9% vs 4.2%). The incidence of major adverse cardiac events (cardiac death, myocardial infarction, and target vessel revascularization) was 9.2%, with no differences between groups. There were no cases of stent thrombosis.

CONCLUSIONS

According to the clinical and angiographic findings, the complex strategy was not significantly superior to the simple approach in the revascularization of bifurcation lesions with second-generation everolimus-drug eluting stents.

The resolute™ integrity zotarolimus-eluting stent in coronary artery disease: a review

The introduction of first-generation drug-eluting stents (DES) was a major advance in the percutaneous treatment of coronary artery disease, with DES significantly reducing the incidence of restenosis and major adverse coronary events compared with bare metal stents. Next-generation DES now utilizes lower profiles, thinner struts, and other technological advances to help extend their safety and efficacy. Importantly, studies of next-generation devices have now gone beyond controlled clinical trials with selected populations to registries and studies with all-comer populations, where more diverse and complex sets of patients and lesions have been managed. Thus, a large body of evidence and comparative data about the safety and efficacy of these devices has accumulated. The Resolute™ zotarolimus-eluting stent (R-ZES; Medtronic Inc., Santa Rosa, CA, USA) is a next-generation DES that uses a novel biocompatible polymer on a cobalt alloy stent platform to extend the duration of drug elution and improve the stent's efficacy. The Integrity™ platform (Medtronic, Inc., Santa Rosa, CA, USA) used in the most recent iteration of the R-ZES stent further enhances the flexibility and deliverability of the stent in complex lesions by incorporation of a continuous sinusoidal design. In the following review, the clinical data is critically examined for the R-ZES and discuss its performance using comparative data currently available for next-generation DES. It is concluded that R-ZES use in complex patients and lesions is associated with durable efficacy and safety and represents another generational improvement in DES technology, which undoubtedly will enhance patient outcomes postpercutaneous coronary interventional.

Towards personalized medicine based on platelet function testing for stent thrombosis patients

Stent thrombosis (ST) is a severe and feared complication of coronary stenting. Patients who have suffered from ST are usually treated according to the “one-size-fits-all” dosing regimen of aspirin and clopidogrel. Many ST patients show high on-treatment platelet reactivity (HPR) despite this antiplatelet therapy (APT). It has been shown that HPR is a risk factor for major adverse cardiac events. Therefore, ST patients with HPR are at a high risk for recurrent atherothrombotic events. New insights into the variable response to clopidogrel and the advent of stronger P2Y12 inhibitors prasugrel and ticagrelor have changed the attention from a fixed APT treatment strategy towards “personalized APT strategies.” Strategies can be based on platelet function testing, which gives insight into the overall response of a patient to APT. At our outpatient ST clinic, we practice personalized APT based on platelet function testing to guide the cardiologist to a presumed optimal antiplatelet treatment of ST patients. Beside results of platelet function testing, comedication, clinical characteristics, and genetics have to be considered to decide on personalized APT. Ongoing studies have yet to reveal the optimal personalized APT strategy for cardiologists to prevent their patients from atherothrombotic and bleeding events.

Stent thrombosis: an overview

Stent thrombosis is a challenging problem following percutaneous coronary intervention that can lead to serious clinical consequences, such as death and acute myocardial infarction. Its pathophysiology is not yet completely known, and there are several causes suggested, such as incomplete stent endothelization, presence of polymers and late incomplete stent apposition. One of the main predictors is the early discontinuation of dual antiplatelet therapy. Stent improvements related to their design, with more friendly metallic platforms, thinner biocompatible or biodegradable polymers, absence of polymers, and even stents manufactured with bioabsorbable materials, could make the percutaneous procedure much safer and effective, allowing its application in increasingly complex anatomic and clinical scenarios, with low thrombosis rates.

The importance of the endothelium in atherothrombosis and coronary stenting

Deployment of drug-eluting stents instead of bare-metal stents has dramatically reduced restenosis rates, but rates of very late stent thrombosis (>1 year postimplantation) have increased. Vascular endothelial cells normally provide an efficient barrier against thrombosis, lipid uptake, and inflammation. However, endothelium that has regenerated after percutaneous coronary intervention is incompetent in terms of its integrity and function, with poorly formed cell junctions, reduced expression of antithrombotic molecules, and decreased nitric oxide production. Delayed arterial healing, characterized by poor endothelialization, is the primary cause of late (1 month-1 year postimplantation) and very late stent thrombosis following implantation of drug-eluting stents. Impairment of vasorelaxation in nonstented proximal and distal segments of stented coronary arteries is more severe with drug-eluting stents than bare-metal stents, and stent-induced flow disturbances resulting in complex spatiotemporal shear stress can also contribute to increased thrombogenicity and inflammation. The incompetent endothelium leads to late stent thrombosis and the development of in-stent neoatherosclerosis. The process of neoatherosclerosis occurs more rapidly, and more frequently, following deployment of drug-eluting stents than bare-metal stents. Improved understanding of vascular biology is crucial for all cardiologists, and particularly interventional cardiologists, as maintenance of a competently functioning endothelium is critical for long-term vascular health.

Randomized study comparing everolimus- and sirolimus-eluting stents in patients with bifurcation lesions treated by provisional side-branch stenting

OBJECTIVES

To compare the efficacy of sirolimus- and everolimus-eluting stents in patients with bifurcation lesions treated with provisional side-branch stenting.

BACKGROUND

The efficacy of everolimus-eluting stents in bifurcation lesions has been poorly tested.

METHODS

Patients with all types of Medina bifurcation lesions were randomly assigned to treatment with either a sirolimus- (n = 145) or everolimus-eluting stent (n = 148). We included patients with main vessel diameter over 2.5 mm and side branches over 2.25 mm. Patients with diffuse side-branch stenosis were excluded.

RESULTS

There were no significant differences between patients from the sirolimus and everolimus groups in terms of age, risk factors, clinical status, location of the bifurcation lesions or angiographic variables. Immediate results and in-hospital outcome were also similar in both groups of patients. In-hospital death occurred in two patients, one from each group. Target lesion revascularization was required in nine patients: four patients (2.7%) from the sirolimus group and five patients (3.4%) from the everolimus group. Late cardiac mortality occurred in two patients from the sirolimus group and in one patient from the everolimus group. Major cardiac event rates at 1 year were similar in both groups: nine patients (6.2%) in the sirolimus group and nine patients (6.1%) from the everolimus group (p: ns).

CONCLUSIONS

In patients with bifurcation lesions, no significant differences in clinical outcome at 1-year follow-up were observed between sirolimus- and everolimus-eluting stent groups.

Stent thrombosis: incidence, predictors and new technologies

Some concerns have been raised regarding the risk of late and very late stent thrombosis (ST) following drug-eluting stent implantation. Despite remaining an uncommon complication of percutaneous coronary intervention, when ST occurs, it can be catastrophic to the individual, commonly presenting as acute ST elevation myocardial infarction or sudden cardiac death. The incidence and predictors of ST have been reported in the literature and the role of dual antiplatelet therapies in the avoidance of such a complication remains vital. Ongoing studies are assessing the role of these therapies including platelet reactivity testing, genetic testing and optimum duration of therapy. In addition, newer polymer-free and bioabsorbable stents are under investigation in the quest to potentially minimise the risk of ST.

Second- and third-generation drug-eluting coronary stents: progress and safety

Drug-eluting stents (DES) have revolutionized the treatment of coronary artery disease by reducing the rate of in-stent restenosis from 20-40% with bare-metal stent (BMS) to 6-8% with DES. However, with widespread use of DES, safety concerns have risen due to the observation of late stent thrombosis. With this in mind and better understanding of mechanism and pathophysiology of stent thrombosis, the technological platform, especially innovative anti-restenotic agents, polymeric coatings, and stent platforms, improved with newer DES. Two second-generation DES, the Endeavor zotarolimus-eluting stent (ZES) and the Xience-V everolimus-eluting stent (EES), have provided promising results in both randomized controlled trials (SPIRIT and ENDEAVOR) and registries (E-Five, COMPARE) compared with bare-metal stents (BMS) and first-generation DES. Newer third-generation stent technology, especially biodegradable polymers, polymer-free stents, and biodegradable stents on the basis of poly-L-lactide (PLLA) or magnesium, has been evaluated in preclinical and initial clinical trials. However, despite encouraging initial results, long-term data of large-scale randomized trials as well as registries comparing them to currently approved first- and second-generation DES are still lacking.

How safe and how good are drug-eluting stents?

Percutaneous transluminal coronary angioplasty revolutionized therapy for coronary artery disease. This early promise of a viable alternative to surgical treatment of coronary artery disease was thwarted by the high rates of angiographic restenosis. The advent of stenting reduced the rates of restenosis, although it was hindered by the new problem of in-stent restenosis. It was demonstrated that in-stent restenosis was the result of a new pathology in the form of neointimal hyperplasia, which was a maladaptive healing response to bare-metal stent implantation. Recently, the introduction of drug-eluting stents (DES) technology has offered a new solution to the problem of restenosis. Current evidence suggests that although DES have reduced restenosis rates, important concerns have been raised regarding increased stent thrombosis, myocardial infarction and death. The purpose of this article is to examine the efficacy and safety data of DES as highlighted in recent publications and to further discuss the biomolecular mechanisms of accelerated endothelization and stent thrombosis. In addition, we will examine some of the newer stent technologies available.

[Update in interventional cardiology]

This article contains a detailed review of the most important studies on interventional cardiology reported in either publications or presentations. With regard to coronary interventions, ST-elevation myocardial infarction is highlighted because of the ongoing substantial expansion in primary angioplasty programs. Drug-eluting stents, especially new-generation stents, continue to be the focus of numerous studies. Clinical outcomes in diabetic patients with left main coronary artery or multivessel disease are also dealt with by much research. In addition, intracoronary diagnostic techniques, particularly optical coherence tomography, is reviewed. Finally, there is increasing interest in the percutaneous treatment of structural heart disease, particularly percutaneous aortic valve implantation.

The molecular mechanisms of congenital hypofibrinogenaemia

Congenital hypofibrinogenaemia is characterized by abnormally low levels of fibrinogen and is usually caused by heterozygous mutations in the fibrinogen chain genes (alpha, beta and gamma). However, it does not usually result in a clinically significant condition unless inherited in a homozygous or compound heterozygous state, where it results in a severe bleeding disorder, afibrinogenaemia. Various protein and expression studies have improved our understanding of how mutations causing hypo- and afibrinogenaemia affect secretion of the mature fibrinogen molecule from the hepatocyte. Some mutations can perturb chain assembly as in the gamma153 Cys-->Arg case, while others such as the Bbeta Leu-->Arg and the Bbeta414 Gly-->Ser mutations allow intracellular hexamer assembly but inhibit protein secretion. An interesting group of mutations, such as gamma284 Gly-->Arg and gamma375 Arg-->Trp, not only cause hypofibrinogenaemia but are also associated with liver disease. The nonexpression of these variant chains in plasma fibrinogen is due to retention in the endoplasmic reticulum, which in turn leads to hypofibrinogenaemia.