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- Thienopyridine use after coronary stenting in low income patients enrolled in medicare part d receiving maintenance dialysis. [Journal Article]
- J Am Heart Assoc 2014; 3(5)
Coronary stenting in patients on dialysis has increased by nearly 50% over the past decade, despite heightened risks of associated stent thrombosis and bleeding relative to the general population. We examined clopidogrel, prasugrel or ticlopidine use after percutaneous coronary intervention (PCI) with stenting in patients on dialysis. We conducted 3-, 6-, and 12-month landmark analyses to test the hypothesis that thienopyridine discontinuation prior to those time points would be associated with higher risks of death, myocardial infarction, or repeat revascularization, and a lower risk of major bleeding episodes compared with continued thienopyridine use.Using the US Renal Data System, we identified 8458 patients on dialysis with Medicare Parts A+B+D undergoing PCI with stenting between July 2007 and December 2010. Ninety-nine percent of all thienopyridine prescriptions were for clopidogrel. At 3 months, 82% of patients who received drug-eluting stents (DES) had evidence of thienopyridine use. These proportions fell to 62% and 40% at 6 and 12 months, respectively. In patients who received a bare-metal stent (BMS), 70%, 34%, and 26% of patients had evidence of thienopyridine use at 3, 6, and 12 months, respectively. In patients who received a DES, there was a suggestion of higher risks of death or myocardial infarction associated with thienopyridine discontinuation in the 3-, 6-, and 12-months landmark analyses, but no higher risk of major bleeding episodes. In patients who received a BMS, there were no differences in death or cardiovascular events, and possibly lower risk of major bleeding with thienopyridine discontinuation in the 3- and 6-month landmark analyses.The majority of patients on dialysis who undergo PCI discontinue thienopyridines before 1 year regardless of stent type. While not definitive, these data suggest that longer-term thienopyridine use may be of benefit to patients on dialysis who undergo PCI with DES.
- [Antithrombotic therapy and atrial fibrillation : Dual or triple therapy after acute coronary syndrome and stent?] [JOURNAL ARTICLE]
- Herz 2014 Oct 23.
Current guidelines recommend dual antiplatelet therapy preferably with prasugrel or ticagrelor for 12 months in patients after acute coronary syndrome with stent implantation. Problems occur in patients with a need for oral anticoagulation, such as patients with atrial fibrillation. In these patients a combination of oral anticoagulation and platelet inhibitors is necessary. Antithrombotic combination therapy is known to increase bleeding complications. In a small randomized trial the combination of a vitamin K antagonist (VKA) and clopidogrel decreased bleeding compared to triple therapy with VKA, clopidogrel and aspirin. The new oral anticoagulants have consistently been shown to decrease bleeding complications compared to VKAs regardless of additional antiplatelet therapy. Because of the lack of randomized trials the individual decision about the intensity and duration of antithrombotic combination therapy should be based on the bleeding and ischemic risk in the individual patient. However, in most patients in addition to oral anticoagulation, antiplatelet monotherapy preferably with clopidogrel seems necessary only for 3-6 months.
- Chronic vitamin K antagonist therapy and bleeding risk in ST elevation myocardial infarction patients. [JOURNAL ARTICLE]
- Heart 2014 Oct 21.
Acute management of ST elevation myocardial infarction (STEMI) patients on chronic vitamin K antagonist (VKA) therapy is uncertain. This study aims to estimate in-hospital major bleeding risk among STEMI patients on chronic VKA treated with primary percutaneous coronary intervention (PCI); and determine the relationship between bleeding and acute treatments stratified by international normalised ratio (INR) values.We retrospectively examined 120 270 STEMI patients treated with primary PCI at 586 national registry hospitals (2007-2012).Overall, 3101 patients (2.6%) were on VKA which was associated with increased in-hospital major bleeding risk when compared with patients not on VKA (17.0%, vs 10.1%; adjusted OR 1.26, 95% CI 1.13 to 1.40). In patients on VKA, admission INR ≥2.0 was not associated with an increase in bleeding risk compared to INR <2.0. Patients on VKA were more likely to receive clopidogrel or bivalirudin within 24 h of presentation (acute), but less likely to receive prasugrel, heparin, or glycoprotein IIb/IIIa inhibitors (GPI). In those patients, acute GPI was associated with increased bleeding risk (adjusted OR 1.92, 95% CI 1.54 to 2.40) while bivalirudin was associated with decreased risk (adjusted OR 0.69, 95% CI 0.55 to 0.86); bleeding risk associated with heparin, bivalirudin, ADP-receptor blockers, or GPI was similar between INR ≥2.0 and <2.0.In STEMI patients treated with primary PCI, chronic VKA therapy was associated with a significant increase in in-hospital major bleeding risk compared to no VKA therapy, irrespective of whether admission INR was ≥2.0 or not. In patients on VKA, GPI was associated with increased bleeding risk while bivalirudin was associated with decreased risk.
- Efficacy of cilostazol on platelet reactivity and cardiovascular outcomes in patients undergoing percutaneous coronary intervention: insights from a meta-analysis of randomised trials. [Journal Article]
- Open Heart 2014; 1(1):e000068.
Cilostazol overcomes high on-treatment platelet reactivity (HTPR) and reduces adverse cardiovascular (CV) outcomes after percutaneous coronary intervention (PCI). However, the role for triple antiplatelet therapy (TAPT) with cilostazol in addition to aspirin and clopidogrel after PCI is not well defined.We conducted a MEDLINE/EMBASE/CENTRAL search for randomised trials, until May 2014, evaluating TAPT compared with dual antiplatelet therapy (DAPT) of aspirin and clopidogrel alone in patients undergoing PCI and reporting platelet reactivity and/or CV outcomes. The primary platelet reactivity outcome was differences in platelet reactivity unit (PRU) with secondary outcomes of %platelet inhibition and rate of HTPR. The primary CV outcome was major adverse cardiovascular events (MACE), with secondary outcomes of death, cardiovascular death, myocardial infarction, stent thrombosis (ST), target lesion revascularisation (TLR) and target vessel revascularisation (TVR) as well as safety outcomes of bleeding and drug discontinuations.In 17 trials that evaluated platelet reactivity outcomes, the mean PRU value was 47.73 units lower with TAPT versus DAPT (95% CI -61.41 to -34.04, p<0.0001; mean PRU 182.90 vs 232.65). TAPT also increased platelet inhibition by 12.71% (95% CI 10.76 to 14.67, p<0.0001), and led to a 60% reduction in the risk of HTPR (relative risk=0.40; 95% CI 0.30 to 0.53) compared with DAPT. Moreover, among the 34 trials that evaluated CV outcomes, TAPT reduced the risk of MACE (incident rate ratio (IRR)=0.68; 95% CI 0.60 to 0.78), TLR (IRR=0.57; 95% CI 0.44 to 0.73), TVR (IRR=0.69; 95% CI 0.59 to 0.81) and ST (IRR=0.63; 95% CI 0.40 to 0.98) with no difference for other outcomes including bleeding, even in trials using drug-eluting stents. Drug discontinuation due to adverse effects was, however, higher with TAPT vs DAPT (IRR=1.59; 95% CI 1.32 to 1.91).In patients undergoing PCI, addition of cilostazol to DAPT results in decreased platelet reactivity and a significant reduction in CV outcomes including ST, even in the drug-eluting stent era.
- Influence of race and sex on thrombogenicity in a large cohort of coronary artery disease patients. [Journal Article]
- J Am Heart Assoc 2014; 3(5)
It is uncertain whether sex and race affect thrombogenicity in patients with coronary artery disease. We evaluated the effects of sex and race on thrombogenicity in patients with coronary artery disease treated with aspirin.Patients on aspirin therapy for 1 week or longer with known or suspected coronary artery disease undergoing nonurgent cardiac catheterization (n=1172), of whom 924 were on aspirin and clopidogrel therapy, were studied. The primary end point was thrombin-induced platelet-fibrin clot strength (MAKH) measured by thrombelastography. Secondary end points included coagulation index, a measure of overall coagulation; G, another measure of clot strength; and maximal platelet aggregation. Women had greater MAKH, G, and coagulation index than men, both with and without clopidogrel therapy (with clopidogrel: 68.3±6 versus 65.8±6 mm, P<0.0001; 11.4±3 versus 9.5±4 dyne/cm(2), P<0.0001; and 0.12±3 versus -0.7±3, P=0.003, respectively). Platelet aggregation (induced by ADP, thrombin receptor activating peptide, or collagen) did not differ between sexes. Black patients had greater MAKH and G than white patients (with clopidogrel: 67.8±7 versus 66.4±6 mm, P=0.005; 11±4 versus 10±3 dyne/cm(2), P=0.02, respectively). Black women had the highest MAKH levels. By multivariate analysis, sex, race, diabetes, platelet count, and hemoglobin level were independently associated with MAKH . Sex, but not race, was also associated with the frequency of MAKH ≥72 mm (a threshold related to ischemic event occurrence in patients undergoing coronary intervention).Sex and race independently influence platelet-fibrin clot strength. Black women appear to have the highest thrombogenicity profile, potentially conferring a high-risk phenotype for thrombotic event occurrence.
- Mitochondrial toxicity of cardiac drugs and its relevance to mitochondrial disorders. [JOURNAL ARTICLE]
- Expert Opin Drug Metab Toxicol 2014 Oct 21.:1-10.
Introduction: One target of toxicity caused by cardiac drugs is the mitochondrion. This review focuses on the mitochondrion-toxic effects of cardiac drugs and the extent to which mitochondrion-mediated side effects influence the treatment of cardiac disease in mitochondrial disorders (MIDs). Areas covered: Areas discussed in this review include the pathogenesis of mitochondrion toxicity and the mechanisms by which cardiac drugs exhibit their mitochondrion-toxic effect. Whenever available, the mitochondrion-toxic effect of cardiac drugs in patients with a MID is highlighted. Expert opinion: Most of the drugs used in cardiology are somewhat mitochondrion-toxic. The degree of toxicity, however, is variable and dependent on the type of drug, tissue, organ, subject, cell system investigated, the co-medication, and the conditions under which the investigations have been carried out. Abnormalities induced by mitochondrion-toxic cardiac drugs include impairment of respiratory chain functions resulting in reduced ATP production, increased production of reactive oxygen species with increased oxidation of proteins or lipids, reduction of the mitochondrial membrane potential and apoptosis. Several other mitochondrial functions may be additionally impaired by culprit compounds. Cardiac drugs that should be applied with particular caution in patients with MIDs include amiodarone, phenytoin, lidocaine, quinidine, isoproterenol, clopidogrel, acetyl-salicylic acid and molsidomine.
- Effects of Cytochrome P450 2C19 and Paraoxonase 1 Polymorphisms on Antiplatelet Response to Clopidogrel Therapy in Patients with Coronary Artery Disease. [JOURNAL ARTICLE]
- PLoS One 2014; 9(10):e110188.
Clopidogrel is an antiplatelet prodrug that is recommended to reduce the risk of recurrent thrombosis in coronary artery disease (CAD) patients. Paraoxonase 1 (PON1) is suggested to be a rate-limiting enzyme in the conversion of 2-oxo-clopidogrel to active thiol metabolite with inconsistent results. Here, we sought to determine the associations of CYP2C19 and PON1 gene polymorphisms with clopidogrel response and their role in ADP-induced platelet aggregation. Clopidogrel response and platelet aggregation were determined using Multiplate aggregometer in 211 patients with established CAD who received 75 mg clopidogrel and 75-325 mg aspirin daily for at least 14 days. Polymorphisms in CYP2C19 and PON1 were genotyped and tested for association with clopidogrel resistance. Linkage disequilibrium (LD) and their epistatic interaction effects on ADP-induced platelet aggregation were analysed. The prevalence of clopidogrel resistance in this population was approximately 33.2% (n = 70). The frequencies of CYP2C19*2 and *3 were significantly higher in non-responder than those in responders. After adjusting for established risk factors, CYP2C19*2 and *3 alleles independently increased the risk of clopidogrel resistance with adjusted ORs 2.94 (95%CI, 1.65-5.26; p<0.001) and 11.26 (95%CI, 2.47-51.41; p = 0.002, respectively). Patients with *2 or *3 allele and combined with smoking, diabetes and increased platelet count had markedly increased risk of clopidogrel resistance. No association was observed between PON1 Q192R and clopidogrel resistance (adjusted OR = 1.13, 95%CI, 0.70-1.82; p = 0.622). Significantly higher platelet aggregation values were found in CYP2C19*2 and *3 patients when compared with *1/*1 allele carriers (p = 1.98×10-6). For PON1 Q192R genotypes, aggregation values were similar across all genotype groups (p = 0.359). There was no evidence of gene-gene interaction or LD between CYP2C19 and PON1 polymorphisms on ADP-induced platelet aggregation. Our findings indicated that only CYP2C19*2 and *3 alleles had an influence on clopidogrel resistance. The risk of clopidogrel resistance increased further with smoking, diabetes, and increased platelet count.
- Research on intracranial atherosclerosis from the East and west: why are the results different? [Journal Article, Review]
- J Stroke 2014 Sep; 16(3):105-13.
Intracranial atherosclerosis (ICAS) is a major cause of stroke worldwide and is more common in Asians than Caucasians. The study results from the East and West are generally similar, but notable differences exist. For example, studies from the East have reported that ICAS is associated with young age, whereas ICAS seems to be associated with old age in the West. Studies from the East have strongly suggested that mild ICAS associated with branch occlusion is one of the main causes of single subcortical infarction, whereas this aspect has not been considered in stroke classification systems developed in the West. While clopidogrel is commonly used in patients with large artery disease in the West, cilostazol has been more extensively studied and commonly used in ICAS patients in the East. A randomized controlled study from the West reported negative results regarding the efficacy of stenting in ICAS patients due largely to a relatively high rate of periprocedural adverse events, whereas research papers from the East have reported a relatively lower rate of complications. Studies to narrow these East-West gaps should be performed, including risk factor studies using homogenous ethnic populations, studies investigating appropriate classification systems, drug trials in different ethnic populations, and rigorous high standard randomized controlled studies on the efficacy of stenting in Eastern populations.
- Clopidogrel: A multifaceted affair. [JOURNAL ARTICLE]
- J Clin Pharmacol 2014 Oct 18.
Clopidogrel has been the therapy of choice, combined with aspirin, against platelet aggregation in patients at risk of suffering a vascular thrombotic event. Not all patients respond equally to clopidogrel, an observation that has led to searching for a test that, in the clinical setting, could predict patients' "resistance" to therapy. The evidence reveals a complex pharmacokinetic profile for clopidogrel, with multiple players involved, including cytochromes, characteristics of the target tissue and accompanying clinical conditions. Despite FDA Black Box warnings recommending CYP2C19 genotyping before clopidogrel use, no robust evidence indicates that CYP2C19 function determines clinical response to the drug, either based on the presence of loss of function alleles or drug interactions with CYP2C19 inhibitors, like omeprazole. A tailored anti-aggregation treatment based on ex vivo platelet reactivity also seems unlikely due to the lack of robustness of most assays. The identification of clinical conditions that are at higher risk of new cardiovascular events, such as diabetes, obesity, coronary artery disease, or specifc stenting procedures seems to be a prudent approach to tailor anti-platelet therapy with more powerful drugs, accompanied by careful counseling to promote patient compliance.
- Relation between the Change in Mean Platelet Volume and Clopidogrel Resistance in Patients Undergoing Percutaneous Coronary Intervention. [JOURNAL ARTICLE]
- Curr Vasc Pharmacol 2014 Oct 17.
We aimed to determine the association between the change in mean platelet volume (MPV) over time and aspirin/ clopidogrel resistance in patients undergoing percutaneous coronary intervention (PCI). The MPV and platelet function were analysed in 302 patients who underwent PCI. MPV changes were associated with increased aspirin reaction units (ARU, r = 0.114; P = 0.047), increased P2Y12 reaction units (PRU, r = 0.193; P = 0.001), and decreased P2Y12% inhibition (PI%, r = - 0.273; P < 0.001). The group with increasing MPV values showed significantly higher PRU values and lower PI% compared with the group with decreasing MPV values (222.5 ± 73.9 vs. 195.6 ± 63.7 PRU, P = 0.001; 24.1 ± 21.0 vs. 32.8 ± 18.5 PI%, P < 0.001, respectively). The clopidogrel resistant group (≥235 PRU or ≤15% of PI%) showed a significantly higher positive change in MPV (ΔMPV) values than the clopidogrel responder group (0.53 ± 0.78 vs. 0.13 ± 0.69 fL, P < 0.001). When the ΔMPV cut-off level was set at 0.20 fL using the receiver operating characteristic curve, the sensitivity and specificity for differentiating between the clopidogrel resistant and responder groups were 72.6% and 59.3%, respectively. After adjusting for traditional risk factors, the odds ratio in the clopidogrel resistant group with ΔMPV ≥0.2 fL was 4.10 (95% confidence interval; 1.84-9.17). In conclusion, ΔMPV was associated with PRU and PI%; a positive ΔMPV was an independent predictive marker for clopidogrel resistance after PCI.