Adnan Kastrati

Predictive Factors of Restenosis After Coronary Stent Placement

OBJECTIVES The objective of this study was to identify clinical, lesional and procedural factors that can predict restenosis after coronary stent placement. BACKGROUND Coronary stent placement reduces the restenosis rate compared with that after percutaneous transluminal coronary angioplasty (PTCA). However, restenosis remains an unresolved issue, and identification of its predictive factors may allow further insight into the underlying process. METHODS All patients with successful coronary stent placement were eligible for this study unless they had had a major adverse cardiac event during the 1st 30 days after the procedure. Of the 1,349 eligible patients (1,753 lesions), follow-up angiography at 6 months was performed in 80.4% (1,084 patients, 1,399 lesions). Demographic, clinical, lesional and procedural data were prospectively recorded and analyzed for any predictive power for the occurrence of late restenosis after stenting. Restenosis was evaluated by using three outcomes at follow-up: binary restenosis as a diameter stenosis > or =50%, late lumen loss as lumen diameter reduction and target lesion revascularization (TLR) as any repeat PTCA or coronary artery bypass surgery involving the stented lesion. RESULTS Multivariate analysis demonstrated that diabetes mellitus, placement of multiple stents and minimal lumen diameter (MLD) immediately after stenting were the strongest predictors of restenosis. Diabetes increased the risk of binary restenosis with an odds ratio (OR) [95% confidence interval] of 1.86 [1.56 to 2.16] and the risk of TLR with an OR of 1.45 [1.11 to 1.80]. Multiple stents increased the risk of binary restenosis with an OR of 1.81 [1.55 to 2.06] and that of TLR with an OR of 1.94 [1.66 to 2.22]. An MLD <3 mm at the end of the procedure augmented the risk of binary restenosis with an OR of 1.81 [1.55 to 2.06] and that of TLR with an OR of 2.05 [1.77 to 2.34]. Classification and regression tree analysis demonstrated that the incidence of restenosis may be as low as 16% for a lesion without any of these risk factors and as high as 59% for a lesion with a combination of these risk factors. CONCLUSIONS Diabetes, multiple stents and smaller final MLD are strong predictors of restenosis after coronary stent placement. Achieving an optimal result with a minimal number of stents during the procedure may significantly reduce this risk even in patients with adverse clinical characteristics such as diabetes.

Absorption, Metabolization, and Antiplatelet Effects of 300-, 600-, and 900-mg Loading Doses of Clopidogrel Results of the ISAR-CHOICE (Intracoronary Stenting and Antithrombotic Regimen: Choose Between 3 High Oral Doses for Immediate Clopidogrel Effect) Trial

Background— For patients undergoing percutaneous coronary intervention, the administration of a clopidogrel loading dose ranging from 300 to 600 mg is currently recommended. It is unknown, though, whether loading doses higher than 600 mg exert additional suppression of platelet function. Methods and Results— Sixty patients with suspected or documented coronary artery disease admitted to our hospital for coronary angiography were included in this trial. They were allocated to 1 of 3 clopidogrel loading doses (300, 600, or 900 mg) in a double-blinded, randomized manner. Plasma concentrations of the active thiol metabolite, unchanged clopidogrel, and the inactive carboxyl metabolite of clopidogrel were determined before and serially after drug administration. Optical aggregometry was performed before and 4 hours after administration of clopidogrel. Loading with 600 mg resulted in higher plasma concentrations of the active metabolite, clopidogrel, and the carboxyl metabolite compared with loading with 300 mg (P≤0.03) and lower values for adenosine diphosphate-induced (5 and 20 &mgr;mol/L) platelet aggregation 4 hours after drug administration (P=0.01 and 0.004). With administration of 900 mg, no further increase in plasma concentrations of active metabolite and clopidogrel (P≥0.38) and no further suppression of adenosine diphosphate-induced (5 and 20 &mgr;mol/L) platelet aggregation 4 hours after drug administration was achieved when compared with administration of 600 mg (P=0.59 and 0.39). Conclusions— Single doses of clopidogrel higher than 600 mg are not associated with an additional significant suppression of platelet function because of limited clopidogrel absorption.

Platelet reactivity after clopidogrel treatment assessed with point-of-care analysis and early drug-eluting stent thrombosis.

OBJECTIVES The aim of this prospective trial was to assess whether platelet reactivity to clopidogrel assessed with multiple electrode platelet aggregometry (MEA) correlates with the risk of early drug-eluting stent thrombosis (ST). BACKGROUND Studies using light transmission aggregometry (LTA) have shown that insufficient suppression of platelet reactivity to adenosine diphosphate (ADP) after clopidogrel treatment is associated with an increased risk of adverse cardiovascular events after percutaneous coronary intervention (PCI). However, LTA is time- and labor-intensive and inconvenient for the routine. A point-of-care assay with similar predictive power would be of great value. METHODS Between February 2007 and April 2008, a total of 1,608 consecutive patients with coronary artery disease and planned drug-eluting stent implantation were enrolled. Before PCI, all patients received 600 mg clopidogrel. Blood was obtained directly before PCI. The ADP-induced platelet aggregation was assessed in whole blood with MEA on a Multiplate analyzer (Dynabyte, Munich, Germany). The primary end point was definite ST at 30 days. RESULTS The upper quintile of patients according to MEA measurements (n = 323) was defined as clopidogrel low responders. Compared with normal responders (n = 1,285), low responders had a significantly higher risk of definite ST within 30 days (2.2% vs. 0.2%; odds ratio [OR]: 9.4; 95% confidence interval [CI]: 3.1 to 28.4; p < 0.0001). Mortality rates were 1.2% in low versus 0.4% in normal responders (OR: 3.2; 95% CI: 0.9 to 11.1; p = 0.07). The composite of death or ST was higher in low versus normal responders (3.1% vs. 0.6%; OR: 5.1; 95% CI: 2.2 to 11.6; p < 0.001). CONCLUSIONS Low response to clopidogrel assessed with MEA is significantly associated with an increased risk of ST. Further studies are warranted to evaluate the ability of MEA to guide antiplatelet therapy in patients undergoing PCI.

Diabetes mellitus and the clinical and angiographic outcome after coronary stent placement

OBJECTIVES The objectives of this study were to analyze the clinical and angiographic outcome of diabetic patients with successful coronary stent placement and to compare these results with those achieved after stenting in nondiabetic patients. BACKGROUND The outcome of diabetic patients treated with stent placement due to coronary artery disease has not been assessed comprehensively. METHODS This study analyzes a consecutive series of patients with successful stent placement comprising 715 patients with diabetes and 2,839 patients without diabetes. Clinical one year follow-up and angiographic control at 6 months were part of the protocol. Death, myocardial infarction and target lesion revascularization were considered as adverse events. An automated edge detection system was used for the angiographic assessment. The primary clinical endpoint was event-free survival at one year. The primary angiographic endpoint was restenosis rate at 6 months (> or = 50% diameter stenosis). RESULTS Event-free survival was significantly lower in diabetic than in nondiabetic patients (73.1 vs. 78.5%, p < 0.001). Survival free of myocardial infarction was also significantly reduced in the diabetic group (89.9 vs. 94.4% in nondiabetics, p < 0.001). The incidence of both restenosis (37.5 vs. 28.3%, p < 0.001) and stent vessel occlusion (5.3 vs. 3.4%, p = 0.037) was significantly higher in diabetic patients. Diabetes was identified as an independent risk factor for adverse clinical events and restenosis in multivariate analyses. CONCLUSIONS Patients with diabetes mellitus have a less favorable clinical outcome at one year after successful stent placement as compared to the nondiabetic patients. The clinical follow-up was characterized by a higher incidence of death, myocardial infarction and reinterventions. Diabetic patients also demonstrated an increased risk for restenosis.

Cytochrome 2C19*17 Allelic Variant, Platelet Aggregation, Bleeding Events, and Stent Thrombosis in Clopidogrel-Treated Patients With Coronary Stent Placement

Background— The cytochrome P450 (CYP) 2C19 isoenzyme plays an important role in clopidogrel metabolization. A recently explored CYP2C19*17 allelic variant has been linked to increased transcriptional activity, resulting in extensive metabolization of CYP2C19 substrates, which may lead to an enhanced platelet response to clopidogrel treatment. The aim of this study was to assess the impact of CYP2C19*17 on ADP-induced platelet aggregation, the risk of bleeding, and stent thrombosis in clopidogrel-treated patients undergoing percutaneous coronary intervention. Methods and Results— The study population included 1524 patients undergoing percutaneous coronary intervention after pretreatment with 600 mg clopidogrel. Genotypes were determined with a TaqMan assay. ADP-induced platelet aggregation was assessed on a Multiplate analyzer. The primary clinical safety end point was the 30-day incidence of bleeding defined according to Thrombolysis in Myocardial Infarction criteria, and the primary clinical efficacy end point was the 30-day incidence of stent thrombosis. For both heterozygous (*wt/*17; n=546) and homozygous (*17/*17; n=76) allele carriers, significantly lower ADP-induced platelet aggregation values were found compared with wild-type homozygotes (*wt/*wt; n=902; P=0.039 and P=0.008, respectively). CYP2C19*17 allele carriage was significantly associated with an increased risk of bleeding; the highest risk was observed for CYP2C19*17 homozygous patients (P=0.01, &khgr;2 test for trend). Multivariate analysis confirmed the independent association of CYP2C19*17 allele carriage with platelet aggregation values (P<0.001) and the occurrence of bleeding (P=0.006). No significant influence of CYP2C19*17 on the occurrence of stent thrombosis was found (P=0.79). Conclusions— CYP2C19*17 carrier status is significantly associated with enhanced response to clopidogrel and an increased risk of bleeding.

Vessel Size and Long-Term Outcome After Coronary Stent Placement

BACKGROUND The role of coronary stenting in the treatment of patients with small vessels is not well defined. The purpose of this study was to investigate the influence of vessel size on long-term clinical and angiographic outcome after coronary stent placement. METHODS AND RESULTS The study comprised 2602 patients with successful stent implantation for symptomatic coronary artery disease. Patients were subdivided into 3 equally sized groups (tertiles) according to vessel size, with respective ranges of <2.8, 2.8 to 3.2, and >3.2 mm. Event-free survival at 1 year was 69.5% in the group with smaller vessels, 77.5% in the second group, and 81% in the group with larger vessels (P<0.001). Late lumen loss was similar between the 3 groups (1.12+/-0.73, 1.12+/-0.79, and 1.09+/-0. 88 mm, respectively). Angiographic restenosis rate was significantly higher in the small-vessel group (38.6%, 28.4%, and 20.4% in groups 1, 2, and 3, respectively; P<0.001). The analysis identified subgroups with different risk for restenosis even among patients with small vessels. Within this group, the restenosis rate may be as low as 29.6% in patients without additional risk factors and as high as 53.5% in patients with diabetes and complex lesions. CONCLUSIONS Patients with small vessels present a higher risk for an adverse outcome after coronary stent placement because of a higher incidence of restenosis. However, the unusually high risk for restenosis is confined to those patients with small vessels who have concomitant risk factors such as diabetes and complex lesions.

Cytochrome P450 2C19 loss-of-function polymorphism and stent thrombosis following percutaneous coronary intervention.

AIMS Several studies have demonstrated that the mutant *2 allele of the CYP2C19 681G>A loss-of-function polymorphism is associated with diminished metabolization of clopidogrel into its active thiol metabolite and an attenuated platelet response to clopidogrel treatment. It is not known whether patients carrying the mutant CYP2C19*2 allele have a higher risk of stent thrombosis (ST) compared with homozygous CYP2C19*1 wild-type allele carriers following percutaneous coronary intervention (PCI). The aim of this study was to assess the impact of the CYP2C19 681G>A loss-of-function polymorphism on ST following PCI performed after pre-treatment with clopidogrel. METHODS AND RESULTS The study population included 2485 consecutive patients undergoing coronary stent placement after pre-treatment with 600 mg of clopidogrel. Genotypes were determined with a TaqMan assay. The primary endpoint of the study was the incidence of definite ST within 30 days following PCI. Of the patients studied, 1805 (73%) were CYP2C19 wild-type homozygotes (*1/*1) and 680 (27%) carried at least one *2 allele (*1/*2 or *2/*2). The cumulative 30-day incidence of ST was significantly higher in CYP2C19*2 allele carriers (*1/*2 or *2/*2) vs. CYP2C19 wild-type homozygotes (*1/*1) [10 patients (1.5%) in CYP2C19*2 allele carriers vs. 7 (0.4%) in CYP2C19 wild-type homozygotes (*1/*1), HR 3.81, 95% CI 1.45-10.02, P = 0.007; P = 0.006 after adjustment for confounding variables]. The risk of ST was highest (2.1%) in patients with the CYP2C19 *2/*2 genotype (P = 0.002). CONCLUSION CYP2C19*2 carrier status is significantly associated with an increased risk of ST following coronary stent placement.

Antiplatelet effects of clopidogrel and bleeding in patients undergoing coronary stent placement

Summary.  Background: In patients undergoing percutaneous coronary intervention (PCI), a link between bleeding and excess mortality has been demonstrated. A potential association of platelet response to clopidogrel and bleeding has not been well established yet. Objectives: The aim of the present study was to assess the impact of clopidogrel responsiveness on the risk of bleeding in clopidogrel‐treated patients undergoing PCI. Methods: Patients (n = 2533) undergoing PCI after pretreatment with 600 mg of clopidogrel were enrolled in this study. Blood was obtained directly before PCI. Adenosine‐diphosphate (ADP)‐induced platelet aggregation was assessed on a Multiplate analyzer. The primary endpoint was the incidence of in‐hospital Thrombolysis in Myocardial Infarction (TIMI) major bleeding and the secondary endpoint was in‐hospital TIMI minor bleeding. Receiver‐operator curve (ROC) analysis was used to derive the optimal platelet aggregation value defining enhanced clopidogrel responders for the association of measurements with major bleeding. Results: Thirty‐four (1.3%) major bleeding events and 137 (5.4%) minor bleeding events were observed. The risk of a major bleeding was significantly higher in patients (n = 975) with an enhanced response to clopidogrel as compared with the remaining patients (n = 1558) (2.2 vs. 0.8%, unadjusted odds ratio (OR) 2.6, 95% confidence interval (CI) 1.3–5.2, P = 0.005; adjusted OR 3.5, 95% CI 1.6–7.3, P = 0.001). No significant differences between both groups were observed for the occurrence of minor bleeding events (P = 0.68). Conclusions: Enhanced clopidogrel responsiveness is associated with a higher risk of major bleeding. Whether guidance of antiplatelet treatment based on platelet function testing proves useful for avoiding bleeding events warrants further investigation.

Inactivating mutations in NPC1L1 and protection from coronary heart disease

BACKGROUND Ezetimibe lowers plasma levels of low-density lipoprotein (LDL) cholesterol by inhibiting the activity of the Niemann-Pick C1-like 1 (NPC1L1) protein. However, whether such inhibition reduces the risk of coronary heart disease is not known. Human mutations that inactivate a gene encoding a drug target can mimic the action of an inhibitory drug and thus can be used to infer potential effects of that drug. METHODS We sequenced the exons of NPC1L1 in 7364 patients with coronary heart disease and in 14,728 controls without such disease who were of European, African, or South Asian ancestry. We identified carriers of inactivating mutations (nonsense, splice-site, or frameshift mutations). In addition, we genotyped a specific inactivating mutation (p.Arg406X) in 22,590 patients with coronary heart disease and in 68,412 controls. We tested the association between the presence of an inactivating mutation and both plasma lipid levels and the risk of coronary heart disease. RESULTS With sequencing, we identified 15 distinct NPC1L1 inactivating mutations; approximately 1 in every 650 persons was a heterozygous carrier for 1 of these mutations. Heterozygous carriers of NPC1L1 inactivating mutations had a mean LDL cholesterol level that was 12 mg per deciliter (0.31 mmol per liter) lower than that in noncarriers (P=0.04). Carrier status was associated with a relative reduction of 53% in the risk of coronary heart disease (odds ratio for carriers, 0.47; 95% confidence interval, 0.25 to 0.87; P=0.008). In total, only 11 of 29,954 patients with coronary heart disease had an inactivating mutation (carrier frequency, 0.04%) in contrast to 71 of 83,140 controls (carrier frequency, 0.09%). CONCLUSIONS Naturally occurring mutations that disrupt NPC1L1 function were found to be associated with reduced plasma LDL cholesterol levels and a reduced risk of coronary heart disease. (Funded by the National Institutes of Health and others.).

ISAR-SAFE: a randomized, double-blind, placebo-controlled trial of 6 vs. 12 months of clopidogrel therapy after drug-eluting stenting

BACKGROUND In patients receiving aspirin, the optimal duration of clopidogrel therapy after drug-eluting stent (DES) implantation remains unclear. METHODS This multicentre, randomized, double-blind, placebo-controlled trial tested the hypothesis that in patients undergoing DES implantation, 6 months of clopidogrel is non-inferior to 12 months in terms of clinical outcomes. At 6 months after DES implantation, patients on clopidogrel were randomly assigned to either a 6-month period of placebo or an additional 6-month period of clopidogrel. The primary endpoint was the composite of death, myocardial infarction, stent thrombosis, stroke, and thrombolysis in myocardial infarction major bleeding at 9 months after randomization. RESULTS Owing to slow recruitment and low event rates, the trial was stopped prematurely after enrolment of 4005 of 6000 planned patients. Of 4000 patients included in the final analysis, 1997 received 6 months of clopidogrel and 2003 received 12 months. The primary endpoint occurred in 29 patients (1.5%) assigned to 6 months of clopidogrel and 32 patients (1.6%) assigned to 12 months, observed difference -0.1%, upper limit of one-sided 95% confidence interval (CI) 0.5%, limit of non-inferiority 2%, Pfor noninferiority <0.001. Stent thrombosis was observed in five patients (0.3%) assigned to 6 months of clopidogrel and three patients (0.2%) assigned to 12 months; hazard ratio (HR) 1.66, 95% CI: 0.40-6.96, P = 0.49. Thrombolysis in myocardial infarction major bleeding was observed in 4 patients (0.2%) assigned to 6 months clopidogrel and 5 patients (0.3%) assigned to 12 months; HR 0.80, 95% CI: 0.21-2.98, P = 0.74. CONCLUSIONS In the present trial, characterized by low event rates, we did not observe a significant difference in net clinical outcome between 6 and 12 months of clopidogrel therapy after DES implantation. However, the results of the trial must be considered in view of its premature termination and lower than expected event rates. The trial is registered with ClinicalTrials.gov, Identifier: NCT00661206.