Stent thrombosis: incidence and related factors in the R.I.S.E. Registry(Registro Impianto Stent Endocoronarico)

[Decreasing incidence of stent thrombosis]

Stent thrombosis (ST) remains a major pitfall of stent implantation in contemporary percutaneous coronary intervention (PCI) leading to high rates of death and non-fatal myocardial infarction. Many predictors of ST have been reported worldwide but the strongest have to be highlighted regarding the catastrophic prognosis of such an event. Because platelet aggregation has a pivotal role in ST pathogenesis, the new antiplatelet regimens combining aspirin and P2Y12 receptor inhibitors have led to a remarkable decrease in the ST incidence, especially in the setting of acute coronary syndrome (ACS). In this article, our purpose is to review the evolution of ST incidence since first stent use in PCI. We will also overview the main predictors of ST focusing on ACS and clopidogrel low response.

Environmental influences on endovascular stent platelet reactivity: an in vitro comparison of stainless steel and gold surfaces

Thrombosis is an initiating reaction to vascular injury that follows the placement of vascular devices. Platelets play a crucial role in this response. Their interaction with endovascular devices is not solely a function of device properties, but a multifaceted response dependent on several biological factors that interact in the context of a hemodynamic environment. We sought to investigate the role of local environmental variations on determining indices of biocompatibility. Using a recently described in vitro flow apparatus, we separately studied the platelet and coagulative component responses to stainless steel endovascular stents with and without gold coating. When allowed to interact, these biological mediators of thrombosis enabled varied biocompatibility outcomes in a manner that was dependent on flow. Using platelet reactivity as an index, the stainless steel faired better under some conditions, while under other conditions, gold was superior. Considering such impacts of local environment on biocompatibility is important, both in the interpretation of experimental findings, as well as the continued use and optimized development of vascular devices.

Antiplatelet agents in patients undergoing percutaneous coronary intervention: how many and how much?

Antiplatelet agents play a major role in patients undergoing percutaneous coronary intervention (PCI). Stent thrombosis and the demand for improved clinical outcomes have driven the need for aggressive antiplatelet and anticoagulant regimens and newer, more efficacious, therapies. The benefits of intravenous glycoprotein (GP) IIb/IIIa antagonists and clopidogrel in high-risk patients undergoing PCI appear complementary. In low- to intermediate-risk patients, clopidogrel pre-treatment and a maintenance dose of aspirin + clopidogrel for at least 1 year after PCI are supported by the data, although the optimal duration of clopidogrel treatment beyond 1 year remains hotly contested. The next generation of clinical trials will examine the benefits of antiplatelet and antithrombotic agents as adjunctive therapy with drug-eluting stents. A better understanding of our patients' overall risk will add to procedural success and more durable outcomes.

Estimates of medical device--associated adverse events from emergency departments

BACKGROUND

The true public health burden of adverse events associated with medical devices is unknown. The purpose of this study, therefore, was to produce the first-ever national estimates of medical device-associated adverse events resulting in emergency department (ED) visits.

METHODS

From July 1999 through June 2000, reports of 10,395 medical device-associated adverse events were accumulated using the National Electronic Injury Surveillance System (NEISS), which collects information on product-related injuries from the ED records of a national stratified probability sample of hospitals. The reports were used to estimate annual total number of medical device-associated adverse events as well as number of adverse events associated with specific devices, injury diagnoses, demographic characteristics, and patient disposition status.

RESULTS

The total estimated number of adverse events was 454,383 (95% confidence interval [CI]=371,156-537,610), involving a broad range of devices from 15 medical specialty groups. Unintentional traumatic events associated with a particular device appeared to be the most common mechanism of injury. The most prevalent types of injuries included contusions/abrasions, punctures, and lacerations; 13% of total estimated cases resulted in patient hospitalization. Adverse events occurred within healthcare facilities, and some were occupationally related, although they occurred at home more frequently than any other location (about 42%).

CONCLUSIONS

The magnitude of the total estimate, which is over four times greater than the annual number of adverse event reports received by medical device-regulating surveillance systems, emphasizes medical device-associated adverse events as an under-recognized public health problem. Planned collection of more detailed NEISS data will allow for appropriate public health interventions.

Arterial stenting and overdilation: does it change wall mechanics in small-caliber arteries?

PURPOSE

To evaluate changes in arterial wall mechanics induced by stent overdilation in the rabbit aorta.

METHODS

Twenty New Zealand white rabbits had initial stent deployment (3-mm x 8-mm Multilink) at 10% overdilation. Group A (n=11) had no subsequent balloon expansion of the stent and Group B (n=9) had 30% overdilation of the stent. A noninvasive B-mode ultrasound examination coupled with image processing allowed the measurement of systolic and diastolic diameter and the calculation of diameter compliance (Cd) and distensibility coefficient (DC) as indexes of arterial wall biomechanics. Measurements were performed before stenting in the infrarenal aorta, after initial stenting, and after stent overdilation at 3 locations: upstream, at the stent level, and downstream from the stent.

RESULTS

Cd was significantly lower in the stented aorta after initial stenting (p<0.0001) and after stent overdilation (p<0.0001) than before stenting. At the stent level, Cd and DC were significantly lower than downstream (p<0.0001) or upstream (p<0.0001) from the stent after initial stenting, as well as after stent overdilation. Downstream from the stent, Cd and DC were significantly lower after stent overdilation than before stenting (p<0.05).

CONCLUSIONS

Endovascular stenting of the rabbit aorta produces a significant decrease in arterial wall compliance and distensibility. Stent overdilation is responsible for a slight additional decrease of compliance downstream from the stent.

Low background, pulsatile, in vitro flow circuit for modeling coronary implant thrombosis

We have developed an in vitro method for creating pulsatile flows to mimic coronary type flow patterns on a beat-to-beat basis. The flow is created by accelerating fluid loops about an axis, inducing relative wall motion. Using this technique, a variety of oscillating flow patterns can be generated and modulated. Such flow generation offers the potential to monitor sensitive, flow-dependent, biological parameters like thrombosis while minimizing background disturbances from pump action and circuit effects. We examined this potential by measuring the loop occlusion time for loops stented with stainless steel 7-9 NIR stents and stentless control loops.

Meta-analysis of randomized and registry comparisons of ticlopidine with clopidogrel after stenting

OBJECTIVES

We sought to determine whether clopidogrel is at least as efficacious as ticlopidine.

BACKGROUND

Several trials have supported the enhanced safety and tolerability of clopidogrel compared with ticlopidine after coronary stent deployment. However, none of these individual trials were powered to detect possible differences in the efficacy for reducing ischemic end points.

METHODS

Published data from trials and registries that compared clopidogrel with ticlopidine in patients receiving coronary stents were pooled, and a formal meta-analysis was performed. The rate of 30-day major adverse cardiac events (MACE), as defined in each trial, was used as the primary end point.

RESULTS

There were a total of 13,955 patients. The pooled rate of major adverse cardiac events was 2.10% in the clopidogrel group and 4.04% in the ticlopidine group. After adjustment for heterogeneity in the trials, the odds ratio (OR) of having an ischemic event with clopidogrel, as compared with ticlopidine, was 0.72 (95% confidence interval [CI] 0.59 to 0.89, p = 0.002). Mortality was also lower in the clopidogrel group compared with the ticlopidine group-0.48% versus 1.09% (OR 0.55, 95% CI 0.37 to 0.82; p = 0.003).

CONCLUSIONS

Based on all available evidence from randomized clinical trials or registries, clopidogrel, in addition to better tolerability and fewer side effects, is at least as efficacious as ticlopidine in reducing MACE. This finding may be due to the more rapid onset of an antiplatelet effect seen with the loading dose of clopidogrel, which was used in most of these studies, or to better patient compliance with clopidogrel therapy. Therefore, clopidogrel plus aspirin should replace ticlopidine plus aspirin as the standard antiplatelet regimen after stent deployment.

Self-rated health and clinical status after PTCA: results of a 4-year follow-up in 500 patients

Background: Data on the clinical long-term outcome of patients with coronary artery disease in the years following percutaneous interventions are rare. We therefore decided to conduct a study to: (1) analyze the efficiency of a retrospective inquiry using a questionnaire and (2) perform a clinical long-term follow-up of our patients. Methods and results: Some 45+/-7 months after PTCA, a questionnaire was sent to 549 patients who had been treated at our institution from July 1, 1989, to June 30, 1991. The response rate was 91.1%, with 49 patients (8.9%) lost to follow-up. A total of 115/500 patients (23%) had reinterventions due to severe angina (69 patients (13.8%) undergoing re-PTCA and 46 (9.2%) CABG). Sixteen patients (3.2%) had a myocardial infarction and 35 patients (7.0%) died. Multivariate analysis revealed that patients who were asymptomatic 3 months after PTCA were likely to have a good long-term outcome. This was not found when comparing the clinical status immediately after PTCA to follow-up. Medical therapy with beta-blockers/aspirin/lipid-lowering drugs decreased from 75.2/82.2/35.4% at hospital discharge to 54.6/76.7/25.2% at follow-up. Conclusions: The present study provided important quality data for our institution. The response rate to the questionnaire was surprisingly high (91.1%), indicating that retrospective inquiries may also be efficient. The rate of reinterventions during long-term follow-up (23%) was acceptably low. Good self-rated health 3 months after the intervention turned out to be a strong predictor for a good clinical long-term outcome. Furthermore, we observed an underuse of cardiac medication, something that will be the subject of further quality improvement measures.

Stent thrombosis: historical perspectives and current trends

Coronary stents are now implanted in more than 70% of percutaneous coronary revascularization procedures. Early enthusiasm for improved acute angiographic results and limited restenosis was dampened initially by a high rate of stent thrombosis and later by the increased bleeding complications of aggressive and complex anticoagulation protocols designed to lower the stent thrombosis risk. More recently, routine high-pressure deployment strategies and anti-platelet drug regimens have lowered the incidence of stent thrombosis to approximately 1% without an increased bleeding risk. The timing of stent thrombosis has also changed from a median of 4-5 days to a median of 1 day after the stent procedure. Risk factors in earlier studies included stenting for threatened or abrupt closure, smaller vessels, longer lesions, and possibly left anterior descending artery lesion location. Modern studies have shown a slightly increased risk for multiple stent use, residual dissection, and smaller final lumen. Optimal therapy for stent thrombosis includes emergent revascularization and anti-thrombotic treatment, although the clinical consequences remain dire despite successful reperfusion. The use of platelet glycoprotein IIb/IIIa inhibitors, especially in high-risk situations may further reduce the incidence of stent thrombosis.

One-year outcome in multivessel coronary disease patients undergoing coronary stenting

The purpose of this study was to assess 1-year clinical outcome of patients with multivessel coronary artery disease (CAD) who underwent coronary stenting and were prospectively enrolled in the Registro Impianto Stent Endocoronarico (RISE). Of 939 consecutive patients included in the registry, 377 patients with angiographic evidence of multivessel CAD had a 1-year clinical follow-up. All patients underwent PTCA and single or multiple stenting in at least one vessel. Angiographic optimization was usually performed by using high-pressure balloon dilation. After the procedure, continuation of aspirin (at least 250 mg/day) was recommended, whereas the use of anticoagulation or ticlopidine was determined by the physician in charge of the patient in the various centers. Major adverse cardiac events were defined as death, Q-wave or non-Q-wave myocardial infarction and target vessel revascularization. Mean age of patients (311 men, 66 women) was 60 +/- 10 years. Globally, there were 596 stents implanted (72% Palmaz-Schatz stents) in 434 vessels. In about 75% of the procedures, an inflation pressure > 12 atm was used. Angiographic success rate was 98.5%. After stenting, 77% of patients received antiplatelet treatment with ticlopidine and aspirin. During hospitalization, there were 34 major adverse cardiac events in 24 patients. At 1-year follow-up, 309 patients were alive and event-free; cumulative incidence of death, myocardial infarction, and repeat revascularization were 2.9%, 4.7%, and 10.8%, respectively. By Cox regression analysis, multiple stents implantation (HR 1.72, 95% CI 1-2.97), left anterior descending artery revascularization (HR 1.86, 95% CI 1.01-3.42), use of inflation pressure > 12 atm (HR 0.93, 95% CI 0.89-0.97), ticlopidine therapy (HR 0.41, 95% CI 0.23-0.74), and stent length (HR 1.03, 95% CI 1.01-1.05) were associated with 1-year major cardiac events. In patients with multivessel CAD undergoing stent implantation in at least one vessel, 1-year follow-up is favorable and the need for repeat revascularization procedures, based on clinical data, is lower than previously reported for conventional PTCA. Cathet. Cardiovasc. Intervent. 48:343-349, 1999.