Jurriën M. ten Berg

Paraoxonase-1 is a major determinant of clopidogrel efficacy

Clinical efficacy of the antiplatelet drug clopidogrel is hampered by its variable biotransformation into the active metabolite. The variability in the clinical response to clopidogrel treatment has been attributed to genetic factors, but the specific genes and mechanisms underlying clopidogrel bioactivation remain unclear. Using in vitro metabolomic profiling techniques, we identified paraoxonase-1 (PON1) as the crucial enzyme for clopidogrel bioactivation, with its common Q192R polymorphism determining the rate of active metabolite formation. We tested the clinical relevance of the PON1 Q192R genotype in a population of individuals with coronary artery disease who underwent stent implantation and received clopidogrel therapy. PON1 QQ192 homozygous individuals showed a considerably higher risk than RR192 homozygous individuals of stent thrombosis, lower PON1 plasma activity, lower plasma concentrations of active metabolite and lower platelet inhibition. Thus, we identified PON1 as a key factor for the bioactivation and clinical activity of clopidogrel. These findings have therapeutic implications and may be exploited to prospectively assess the clinical efficacy of clopidogrel.

Left Bundle-Branch Block Induced by Transcatheter Aortic Valve Implantation Increases Risk of Death

Background— Transcatheter aortic valve implantation (TAVI) is a novel therapy for treatment of severe aortic stenosis. Although 30% to 50% of patients develop new left bundle-branch block (LBBB), its effect on clinical outcome is unclear. Methods and Results— Data were collected in a multicenter registry encompassing TAVI patients from 2005 until 2010. The all-cause mortality rate at follow-up was compared between patients who did and did not develop new LBBB. Of 679 patients analyzed, 387 (57.0%) underwent TAVI with the Medtronic CoreValve System and 292 (43.0%) with the Edwards SAPIEN valve. A total of 233 patients (34.3%) developed new LBBB. Median follow-up was 449.5 (interquartile range, 174–834) days in patients with and 450 (interquartile range, 253–725) days in patients without LBBB (P=0.90). All-cause mortality was 37.8% (n=88) in patients with LBBB and 24.0% (n=107) in patients without LBBB (P=0.002). By multivariate regression analysis, independent predictors of all-cause mortality were TAVI-induced LBBB (hazard ratio [HR], 1.54; confidence interval [CI], 1.12–2.10), chronic obstructive lung disease (HR, 1.56; CI, 1.15–2.10), female sex (HR, 1.39; CI, 1.04–1.85), left ventricular ejection fraction ⩽50% (HR, 1.38; CI, 1.02–1.86), and baseline creatinine (HR, 1.32; CI, 1.19–1.43). LBBB was more frequent after implantation of the Medtronic CoreValve System than after Edwards SAPIEN implantation (51.1% and 12.0%, respectively; P<0.001), but device type did not influence the mortality risk of TAVI-induced LBBB. Conclusions— All-cause mortality after TAVI is higher in patients who develop LBBB than in patients who do not. TAVI-induced LBBB is an independent predictor of mortality.

A single dose of erythropoietin in ST-elevation myocardial infarction

AIMSnCardioprotective effects of erythropoietin (EPO) have been shown in experimental and smaller clinical studies. We performed a prospective, multicentre, randomized trial to assess the effects of a single high dose of EPO after primary coronary intervention (PCI) for an ST-elevation myocardial infarction (STEMI). Methods and results Patients with a successful PCI for a first STEMI were randomized to receive either standard medical care alone, or in combination with a single bolus with 60,000 IU i.v. of epoetin alfa within 3 h after PCI. Primary endpoint was left ventricular ejection fraction (LVEF) after 6 weeks, assessed by planar radionuclide ventriculography. Pre-specified secondary endpoints included enzymatic infarct size and major adverse cardiovascular events. A total of 529 patients were enrolled (EPO n = 263, control n = 266). At baseline (before EPO administration), groups were well-matched for all relevant characteristics. After a mean of 6.5 (± 2.0) weeks, LVEF was 0.53 (± 0.10) in the EPO group and 0.52 (± 0.11) in the control group (P = 0.41). Median area under the curve (inter-quartile range) after 72 h for creatinine kinase was 50 136 (28 212-76 664)U/L per 72 h in the EPO group and 53 510 (33 973-90 486)U/L per 72 h in the control group (P = 0.058). More major adverse cardiac events occurred in the control than in the EPO group (19 vs. 8; P = 0.032). Conclusion A single high dose of EPO after a successful PCI for a STEMI did not improve LVEF after 6 weeks. However, the use of EPO was related to less major adverse cardiovascular events and a favourable clinical safety profile.nnnCLINICAL TRIAL REGISTRATION INFORMATIONnNCT00449488; http://www.clinicaltrials.gov/ct2/show/NCT00449488?term=voors&rank=2.

Besides CYP2C19*2, the variant allele CYP2C9*3 is associated with higher on-clopidogrel platelet reactivity in patients on dual antiplatelet therapy undergoing elective coronary stent implantation

Introduction The prodrug clopidogrel plays an important role in the prevention of thrombotic events in patients undergoing coronary stenting. However, a substantial number of atherothrombotic events still occur, which can partially be explained by heightened residual platelet reactivity. Several studies report that the genetic variation in CYP2C19 (*2) is associated with an impaired response to clopidogrel. Objectives To evaluate the effect of genetic variants affecting clopidogrels absorption (ABCB1 C1236T, G2677T/A, C3435T), metabolism (CYP2C9*2, *3, CYP2C19*3, CYP3A4*1B, and CYP3A5*3), and pharmacodynamics (P2Y1 A1622G) on top of the influence of CYP2C19*2 on platelet reactivity in patients undergoing elective coronary stenting on dual antiplatelet therapy. Methods Platelet function was assessed by light transmittance aggregometry and VerifyNow P2Y12 assay in 428 consecutive patients. Patients were either on chronic clopidogrel maintenance therapy (75u2009mg/day for >5 days before the intervention) or received a 300u2009mg clopidogrel loading dose (1–5 days before the intervention, followed by 75u2009mg/day). Linear and logistic regression models were used to assess the associations between genetic variants and platelet reactivity and poor responder status. Results In both the treatment groups, CYP2C19*2-carriage was associated with higher platelet reactivity (P<0.03) and poor responder status; 75u2009mg group: adjusted odds ratio (ORadj): 3.8, 95% confidence interval (CI): 2.0–7.2, 300u2009mg group: ORadj: 4.1, 95% CI: 1.6–10.4. In the 300u2009mg group, CYP2C9*3-carriage was associated with higher platelet reactivity (P<0.05) and poor responder status (ORadj: 11.1, 95% CI: 1.6–78.8, P=0.016). Conclusion Besides CYP2C19*2, the variant allele CYP2C9*3 plays an important role in the response to clopidogrel in patients on dual antiplatelet therapy undergoing coronary stenting.

CYP2C19 genotype-guided antiplatelet therapy in ST-segment elevation myocardial infarction patients-Rationale and design of the Patient Outcome after primary PCI (POPular) Genetics study

RATIONALEnIn patients with ST-segment elevation myocardial infarction (STEMI) who undergo primary percutaneous coronary intervention (pPCI), the use of dual antiplatelet therapy is essential to prevent atherothrombotic complications. Therefore, patients are treated with acetylsalicylic acid and clopidogrel, prasugrel, or ticagrelor. Clopidogrel, however, shows a major interindividual variation in antiplatelet effect, which is correlated to an increase in atherothrombotic events in patients with high platelet reactivity. This interindividual variation is partly a result of CYP2C19 genetic variants. Ticagrelor and prasugrel reduce atherothrombotic events but increase bleeding rate and drug costs, as compared with clopidogrel. CYP2C19-based tailoring of antiplatelet therapy might be beneficial to STEMI patients.nnnSTUDY DESIGNnPOPular Genetics (NCT01761786) is a randomized, open-label, multicenter trial involving 2,700 STEMI patients who undergo pPCI. Patients are randomized to CYP2C19 genotyping or routine ticagrelor or prasugrel treatment. In the genotyping group, *1/*1 (wild-type) patients receive clopidogrel, and patients carrying 1 or 2 *2 or *3 loss-of-function alleles receive ticagrelor or prasugrel. The primary net clinical benefit end point is the composite of death, (recurrent) myocardial infarction, definite stent thrombosis, stroke, and Platelet Inhibition and Patient Outcomes (PLATO) major bleeding at 1 year. Primary safety end point is the composite of (PLATO) major and minor bleeding. Cost-effectiveness and quality of life will be assessed by calculating quality-adjusted life-years, net costs per life-year, and per quality-adjusted life-year gained.nnnCONCLUSIONnThe POPular Genetics study is the first large-scale trial comparing CYP2C19 genotype-guided antiplatelet therapy to a nontailored strategy in terms of net clinical benefit, safety, and cost-effectiveness.

Common variation in the platelet receptor P2RY12 gene is associated with residual on-clopidogrel platelet reactivity in patients undergoing elective percutaneous coronary interventions.

Background— The clinical efficacy of clopidogrel is hampered by a large interindividual variability in platelet inhibition. Polymorphisms in the P2RY12 receptor gene have been suggested to contribute to this variability, but previous studies included a relatively small number of patients and incompletely covered the common variation in the P2RY12 gene. The aim of this study was to comprehensively investigate the possible association between common variation in the entire P2RY12 locus and the magnitude of residual on-clopidogrel platelet reactivity measured by 2 commonly used platelet function assays in a large cohort of patients. Methods and Results— A total of 1031 consecutive patients with coronary artery disease who were scheduled for elective percutaneous coronary interventions were enrolled. Platelet function was assessed by means of ADP-induced light-transmittance aggregometry and the VerifyNow P2Y12 assay. Six haplotype-tagging single nucleotide polymorphisms were carefully selected to comprehensively cover the total common variation in the P2RY12 gene and its flanking regulatory regions. Six common haplotypes were inferred from these haplotype-tagging single nucleotide polymorphisms (denoted A to F). Haplotype F was associated with significantly lower residual on-clopidogrel platelet reactivity compared with the reference haplotype A. The size of this effect per haplotype allele was approximately 5% aggregation in the ADP-induced light-transmittance aggregometry (P<0.05) and 11 P2Y12 reaction units in the VerifyNow P2Y12 assay (P<0.05). Conclusions— Common variation in the P2RY12 gene is a significant determinant of the interindividual variability in residual on-clopidogrel platelet reactivity in patients with coronary artery disease.

The golden hour of prehospital reperfusion with triple antiplatelet therapy: A sub-analysis from the Ongoing Tirofiban in Myocardial Evaluation 2 (On-TIME 2) trial early initiation of triple antiplatelet therapy

BACKGROUNDnIt is known that the efficacy of thrombolytic therapy in ST-segment elevation myocardial infarction (STEMI) is highly time dependent with the best efficacy when given within the so-called golden hour. This analysis from the On-TIME 2 trial evaluated the efficacy of triple antiplatelet therapy on initial patency and ST-segment resolution (STR) in relation to time from symptom onset to first medical contact.nnnMETHODSnThe On-TIME 2 trial included 1,398 consecutive STEMI patients referred for primary percutaneous coronary intervention (PCI). Patients were randomized to dual (500 mg aspirin and 600 mg clopidogrel) or triple antiplatelet (500 mg aspirin, 600 mg clopidogrel, and tirofiban 25 μg/kg bolus and 0.15 μg/kg per minute maintenance infusion for 18 hours) pretreatment in the ambulance. Primary outcome of this sub-analysis was initial patency of the infarct-related vessel and STR before PCI according to time from symptom onset to first medical contact in quartiles. In addition, the incidence of aborted myocardial infarction, defined as the absence of a rise in creatinine kinase, was assessed.nnnRESULTSnInitial patency, STR before PCI, and the incidence of aborted myocardial infarction gradually increased with shorter time from symptom onset to first medical contact. Initial Thrombolysis in Myocardial Infarction flow was present in 21.2% in the total population and 26.2%, 21.5%, 18.1%, and 18.8% in the time quartiles, respectively (P for trend=.01). The incidence of complete STR pre-angiography was 16.6% in the total population and 23.4%, 18.2%, 14.7%, and 9.9% in the 4 quartiles, respectively (P for trend<.001). This was largely driven by the effect of triple antiplatelet therapy, which further improved initial patency and STR and led to a significantly higher incidence of aborted myocardial infarction (13.2% vs 8.7%, P=.011), especially in the patients with short duration of symptoms.nnnCONCLUSIONnAntiplatelet pretreatment before primary PCI, including a glycoprotein IIb/IIIa blocker, seems to be most effective when given shortly after symptom onset. Further studies should be performed to test this hypothesis.

Sulfonylureas and on-clopidogrel platelet reactivity in type 2 diabetes mellitus patients.

Clopidogrel is a prodrug that needs to be converted in vivo by several cytochrome (CYP) P450 iso-enzymes to become active. Both clopidogrel and the oral hypoglycemic drug class sulfonylureas are metabolized by the iso-enzyme CYP2C9. The objective of the study was to evaluate the relationship of sulfonylureas and on-clopidogrel platelet reactivity in type 2 diabetes mellitus patients undergoing elective coronary stent implantation. In this prospective, observational study, on-clopidogrel platelet reactivity was quantified using adenosine diphosphate (ADP)-induced light transmittance aggregometry in 139 type 2 diabetes mellitus patients undergoing elective coronary stent implantation treated with clopidogrel and aspirin. High on-clopidogrel platelet reactivity was defined as >70.7% platelet reactivity to 20u2009µmol/L ADP. A total of 53 patients (38.1%) were on concomitant treatment with sulfonylureas. The remaining 86 patients were on other hypoglycemic drugs. On-clopidogrel platelet reactivity was significantly higher in patients with concomitant sulfonylurea treatment as compared to patients without concomitant sulfonylurea treatment (for 5u2009µmol/L ADP: 46.0%u2009±u200911.8 vs. 40.6%u2009±u200916.0; pu2009=u20090.035, adjusted pu2009=u20090.032 and for 20u2009µmol/L ADP: 64.6%u2009±u200910.8 vs. 58.7%u2009±u200915.5; pu2009=u20090.019, adjusted pu2009=u20090.017). The concomitant use of sulfonylureas was associated with a 2.2-fold increased risk of high on-clopidogrel platelet reactivity (OR 2.2, 95% CI 1.1–4.7, pu2009=u20090.039 and after adjustment for confounders: ORadj 2.0, 95% CI 1.0–5.7, pu2009=u20090.048). Concomitant treatment with sulfonylureas might be associated with decreased platelet inhibition by clopidogrel in type 2 diabetes mellitus patients on dual antiplatelet therapy undergoing elective coronary stent implantation.

Higher efficacy of pre-hospital tirofiban with longer pre-treatment time to primary PCI: protection for the negative impact of time delay

AIMSnTo evaluate the impact of longer duration of pre-hospital initiated antiplatelet and antithrombotic therapy on outcome in patients with ST-segment elevation myocardial infarction (STEMI).nnnMETHODS AND RESULTSnIn this sub-analysis of the Ongoing Tirofiban in Myocardial Evaluation (On-TIME) 2 trial, we studied, in 1,370 patients, the effect of pre-treatment time (time from administering study medication to time of angiography) on complete ST-segment resolution (STR), initial patency and 30-day mortality. Study medication consisted of high dose tirofiban (HDT) or control (placebo or no HDT) on top of high dose clopidogrel, aspirin and unfractionated heparin. Median pre-treatment time was 55 min (44-70). Longer pre-treatment was associated with longer transportation times, longer in-hospital delay, longer total ischaemic time (all p<0.001) and higher 30-day mortality (3.6% vs. 1.8%, p=0.046). Longer HDT pre-treatment time was independently associated with increased complete STR both before (odds ratio [OR] 1.51, 95%; confidence interval [CI] 0.98-2.32; p=0.06) and after PCI (OR 1.43, 95%; CI 1.02-2.02; p=0.039) and with a significantly improved initial TIMI 2 or 3 flow (51.4% vs. 43.4%, p=0.042) and reduced 30-day mortality (2.1% vs. 5.0%, p=0.047) as compared to longer control pre-treatment.nnnCONCLUSIONSnLonger time delay before primary PCI is associated with increased mortality. Pre-treatment with high dose tirofiban, however, may compensate for this negative effect by improving ST-segment resolution and initial patency and by reducing mortality. Further studies should be performed to confirm that this is an attractive therapy for patients with longer delays to reperfusion.

Increased incidence of infective endocarditis after the 2009 European Society of Cardiology guideline update: a nationwide study in the Netherlands

AimsnAfter the introduction of the European Society of Cardiology (ESC) guidelines on prevention, diagnosis, and treatment of infective endocarditis (IE) in 2009, prophylaxis for patients at risk became less strict. We hypothesize that there will be a rise in IE after the introduction of the guideline update.nnnMethods and ResultsnWe performed a nationwide retrospective trend study using segmented regression analysis of the interrupted time series. The patient data were obtained via the national healthcare insurance database, which collects all the diagnoses nationwide. We compared the data before and after the introduction of the 2009 ESC guideline. Between 2005 and 2011, a total of 5213 patients were hospitalized with IE in the Netherlands. During this period, there was a significant increase in IE from 30.2 new cases per 1 000 000 in 2005 to 62.9 cases per 1 000 000 in 2011 (P < 0.001). In 2009, the incidence of IE increased significantly above the projected historical trend (rate ratio: 1.327, 95% CI: 1.205-1.462; P < 0.001). This coincides with the introduction of the 2009 ESC guideline. After the introduction of the ESC guideline, the streptococci-positive cultures increased significantly in the following years 2010-11 from 31.1 to 53.2% (P = 0.0031).nnnConclusionnThis observational study shows that there has been a steady increase in the IE incidence between 2005 and 2011. After the introduction of the 2009 ESC guidelines, the incidence increased more than expected from previous historical trends. Furthermore, there was a significant increase in streptococci-related IE cases.