FDA Advisory Panel on the Safety and Efficacy of Drug-Eluting Stents: Summary of Findings and Recommendations

Attribution of Adverse Events Following Coronary Stent Placement Identified Using Administrative Claims Data

Background More than 600 000 coronary stents are implanted during percutaneous coronary interventions (PCIs) annually in the United States. Because no real-world surveillance system exists to monitor their long-term safety, claims data are often used for this purpose. The extent to which adverse events identified with claims data can be reasonably attributed to a specific medical device is uncertain. Methods and Results We used deterministic matching to link the NCDR (National Cardiovascular Data Registry) CathPCI Registry to Medicare fee-for-service claims for patients aged ≥65 years who underwent PCI with drug-eluting stents (DESs) between July 1, 2009 and December 31, 2013. We identified subsequent PCIs within 1 year of the index procedure in Medicare claims as potential safety events. We linked these subsequent PCIs back to the NCDR CathPCI Registry to ascertain how often the revascularization could be reasonably attributed to the same coronary artery as the index PCI (ie, target vessel revascularization). Of 415 306 DES placements in 368 194 patients, 33 174 repeat PCIs were identified in Medicare claims within 1 year. Of these, 28 632 (86.3%) could be linked back to the NCDR CathPCI Registry; 16 942 (51.1% of repeat PCIs) were target vessel revascularizations. Of these, 8544 (50.4%) were within a previously placed DES: 7652 for in-stent restenosis and 1341 for stent thrombosis. Of 16 176 patients with a claim for acute myocardial infarction in the follow-up period, 4446 (27.5%) were attributed to the same coronary artery in which the DES was implanted during the index PCI (ie, target vessel myocardial infarction). Of 24 288 patients whose death was identified in claims data, 278 (1.1%) were attributed to the same coronary artery in which the DES was implanted during the index PCI. Conclusions Most repeat PCIs following DES stent implantation identified in longitudinal claims data could be linked to real-world registry data, but only half could be reasonably attributed to the same coronary artery as the index procedure. Attribution among those with acute myocardial infarction or who died was even less frequent. Safety signals identified using claims data alone will require more in-depth examination to accurately assess stent safety.

Stent selection among patients with chronic kidney disease: Results from the NCDR CathPCI Registry

OBJECTIVES

This study sought to define contemporary rates of drug eluting stent (DES) usage in patients with chronic kidney disease (CKD).

BACKGROUND

Among patients with CKD undergoing percutaneous coronary interventions (PCIs), outcomes are superior for those who receive DES compared to those who receive bare metal stents (BMSs). However, perceived barriers may limit the use of DES in this population.

METHODS

All adult PCI cases from the NCDR CathPCI Registry involving coronary stent placement between July 1, 2009 and December 31, 2015 were analyzed. The rate of DES usage was then compared among four groups, stratified by CKD stage (I/II, III, IV, and V). Subgroup analysis was conducted based on PCI status and indication. Cases were linked to Medicare claims data to assess 1-year mortality.

RESULTS

A total of 3,650,333 PCI cases met criteria for analysis. DES usage significantly declined as renal function worsened (83.0%, 79.9%, 75.6%, and 75.6%, respectively, in the four CKD stages; p < .001). DES usage was universally lower across the four groups in the setting of ST-Elevation Myocardial Infarction (STEMI) (70.6%, 66.5%, 58.7%, 58.0%; p < .001) and higher in the setting of elective PCI (87.6%, 84.9%, 82.3%, 77.9%; p < .0001). DES was associated with improved 1-year survival, and usage increased over time across each group.

CONCLUSIONS

DESs are underutilized in patients with advanced renal dysfunction. Although DES usage has increased over time, variation still exists between patients with normal renal function and those with CKD.

Coronary stents and vascular response to implantation: literature review

Drug-eluting stents (DESs) have minimized the limitations of bare-metal stents (BMSs) after percutaneous coronary interventions. Nevertheless, serious concerns remain about possible late complications of stenting, such as stent thrombosis (ST) and in-stent restenosis (ISR), although the introduction of second-generation DESs seems to have softened the phenomenon, compared to the first-generation ones. ST is a potentially catastrophic event, which has been markedly reduced by optimization of stent implantation, novel stent designs, and dual antiplatelet therapy. The exact mechanism to explain its occurrence is under investigation, and, realistically, multiple factors are responsible. ISR of BMSs has been previously considered as a stable condition with an early peak (at 6 months) of intimal hyperplasia, followed by a regression period beyond 1 year. On the contrary, both clinical and histologic studies of DESs have demonstrated evidence of continuous neointimal growth during long-term follow-up, named "late catch-up" phenomenon. The acknowledgment that ISR is a relatively benign clinical condition has been recently challenged by evidences which reported that patients with ISR can experience acute coronary syndromes. Intracoronary imaging is an invasive technology that allows identifying features of atherosclerotic plaque of stent implanted and of vascular healing after stenting; it is often used to complete diagnostic coronary angiography and to drive interventional procedures. Intracoronary optical coherence tomography is currently considered a state-of-the-art imaging technique; it provides, compared to intravascular ultrasound, better resolution (at least >10 times), allowing the detailed characterization of the superficial structure of the vessel wall. Imaging studies "in vivo," in agreement with histological findings, suggest that chronic inflammation and/or endothelial dysfunction may induce late de novo "neoatherosclerosis" inside both BMSs and DESs. So, neoatherosclerosis has become the prime suspect in the pathogenesis of late stent failure.

Functional Nanoarchitectures For Enhanced Drug Eluting Stents

Different strategies have been investigated to allow for optimum duration and conditions for endothelium healing through the enhancement of coronary stents. In this study, a nanoarchitectured system is proposed as a surface modification for drug eluting stents. Highly oriented nanotubes were vertically grown on the surface of a new Ni-free biocompatible Ti-based alloy, as a potential material for self-expandable stents. The fabricated nanotubes were self-grown from the potential stent substrate, which are also proposed to enhance endothelial proliferation while acting as drug reservoir to hinder Vascular Smooth Muscle Cells (VSMC) proliferation. Two morphologies were synthesized to investigate the effect of structure homogeneity on the intended application. The material was characterized by field-emission scanning electron microscope (FESEM), X-ray diffraction (XRD), Raman spectroscopy, energy dispersive X-ray spectroscopy (EDX), and X-ray photoelectron spectroscopy (XPS). Nanoindentation technique was used to study the mechanical properties of the fabricated material. Cytotoxicity and proliferation studies were performed and compared for the two fabricated nanoarchitectures, versus smooth untextured samples, using in-vitro cultured endothelial cells. Finally, the drug loading capacity was experimentally studied and further supported by computational modeling of the release profile.

Coating Techniques and Release Kinetics of Drug-Eluting Stents

Implantation of drug-eluting stents (DESs) via percutaneous coronary intervention is the most popular treatment option to restore blood flow to occluded vasculature. The many devices currently used in clinic and under examination in research laboratories are manufactured using a variety of coating techniques to create the incorporated drug release platforms. These coating techniques offer various benefits including ease of use, expense of equipment, and design variability. This review paper discusses recent novel DES designs utilizing individual or a combination of these coating techniques and their resulting drug release profiles.

Diagnosis and Evaluation of Stent Thrombosis with Optical Coherence Tomography

Stent thrombosis (ST) is a rare complication of percutaneous coronary interventions (PCI), especially with drug-eluting stents. ST presents as acute myocardial infarction requiring emergent repeat PCI; optimal reperfusion occurs in two-thirds of patients. As a result, ST has been associated with a high mortality rate and a high rate of recurrent thrombosis. We discuss the use of optical coherence tomography (OCT) for the diagnosis and evaluation of ST. OCT-guided ST management seems a feasible, safe, and appropriate approach. Intracoronary assesses the efficacy of coronary thrombus removal procedures and detects the prevalent stent-related factor that caused ST.

Non-cardiac surgery after percutaneous coronary intervention

Perioperative management of patients after percutaneous coronary intervention presents physicians with unique challenges and dilemmas. Although newer generation drug-eluting stents, transcatheter-based therapies, and minimally invasive surgical techniques have changed the medical landscape, guidelines for managing perioperative patients after percutaneous intervention are based largely on expert opinion and inconsistent data from an earlier era. In conclusion, the aims of this review are to summarize the data pertinent to managing patients after percutaneous coronary intervention in the perioperative period and to explore future perspectives.

Novel drug-eluting stents for coronary revascularization

Over the past decades, there has been significant evolution in coronary stents used in percutaneous coronary intervention. The current novel drug-eluting stents available in the United States represent significant advancements compared to angioplasty, bare-metal stents, and the first generation of drug-eluting stents (DES). The Xience everolimus-eluting stents, Promus everolimus-eluting stents, and Resolute zotarolimus-eluting stents currently demonstrate the optimal balance of safety and efficacy. Endeavor zotarolimus-eluting stents have shorter drug-elution courses, and recent evidence suggests that 3 months of dual antiplatelet therapy appears safe, making Endeavor preferred when early discontinuation of dual antiplatelet therapy is warranted. Despite these advances in stent design, the permanent polymer and metallic stent remain in the vessel wall and may precipitate sustained inflammation, persistent vasomotor dysfunction, and in-stent neo-atherosclerosis. Bioresorbable platforms with biodegradable polymers have been developed to overcome the aforementioned limitations, and the outcomes of ongoing clinical trials are eagerly anticipated to determine if these novel stents will further improve clinical outcomes.

Drug-eluting versus bare-metal coronary stents: where are we now?

Drug-eluting stents have dramatically reduced the risk of restenosis, but concerns of an increased risk of stent thrombosis have provided uncertainty about their use. Recent studies have continued to show improved procedural and clinical outcomes with drug-eluting stents both in the setting of acute coronary syndromes and stable coronary artery disease. Newer generation drug-eluting stents (especially everolimus-eluting stents) have been shown to be not only efficacious but also safe with reduced risk of stent thrombosis when compared with bare-metal stents, potentially changing the benchmark for stent safety from bare-metal stents to everolimus-eluting stents. While much progress is being made in the development of bioabsorbable polymer stents, nonpolymer stents and bioabsorbable stent technology, it remains to be seen whether these stents will have superior safety and efficacy outcomes compared with the already much improved rates of revascularization and stent thrombosis seen with newer generation stents (everolimus-eluting stents and resolute zotarolimus-eluting stents).

Acceptance, panic, and partial recovery the pattern of usage of drug-eluting stents after introduction in the U.S. (a report from the American College of Cardiology/National Cardiovascular Data Registry)

OBJECTIVES

Review the use of drug-eluting stents (DES) to evaluate changes in use.

BACKGROUND

The DES were approved after several small studies in carefully selected patients showed dramatic reduction in in-stent restenosis. The DES were then rapidly adopted into routine practice. In 2006, 3 years after introduction, serious concerns regarding long-term safety were raised.

METHODS

We queried the American College of Cardiology/National Cardiovascular Data Registry (ACC/NCDR) CathPCI Registry. The percentage of DES used through mid-2009 was reviewed overall and in subgroups of patients categorized by lesion type, clinical factors, insurance, and hospital characteristics. Multivariable logistic models relating these covariates to DES usage were constructed for 3 relevant time intervals.

RESULTS

A total of 2,247,647 coronary stent procedures were analyzed. By 2005 over 90% of first stents placed were DES. Safety concerns arising in 2006 reduced DES use to 64% of first stent placed. After publication of salutary outcomes data in 2008, usage increased to 76% by mid-2009. The logistic models demonstrated decreased likelihood of DES usage in patients with: 1) ST-segment elevation myocardial infarctions; and 2) no medical insurance. The DES usage increased for in-stent restenosis. Hospital characteristics were not associated with significant differences in DES usage.

CONCLUSIONS

There was rapid adoption of DES into U.S. clinical practice. Concern for late stent thrombosis in 2006 significantly altered DES use with reductions seen in subgroups at risk for thrombosis and patients with no insurance. These rapid cyclic changes after DES introduction reinforce the need for continuous, timely reporting of outcomes data after the introduction of new technologies.