Jean Philippe Collet

Consensus and Future Directions on the Definition of High On-Treatment Platelet Reactivity to Adenosine Diphosphate

The addition of clopidogrel to aspirin treatment reduces ischemic events in a wide range of patients with cardiovascular disease. However, recurrent ischemic event occurrence during dual antiplatelet therapy, including stent thrombosis, remains a major concern. Platelet function measurements during clopidogrel treatment demonstrated a variable and overall modest level of P2Y(12) inhibition. High on-treatment platelet reactivity to adenosine diphosphate (ADP) was observed in selected patients. Multiple studies have now demonstrated a clear association between high on-treatment platelet reactivity to ADP measured by multiple methods and adverse clinical event occurrence. However, the routine measurement of platelet reactivity has not been widely implemented and recommended in the guidelines. Reasons for the latter include: 1) a lack of consensus on the optimal method to quantify high on-treatment platelet reactivity and the cutoff value associated with clinical risk; and 2) limited data to support that alteration of therapy based on platelet function measurements actually improves outcomes. This review provides a consensus opinion on the definition of high on-treatment platelet reactivity to ADP based on various methods reported in the literature and proposes how this measurement may be used in the future care of patients.

Reduced-Function CYP2C19 Genotype and Risk of Adverse Clinical Outcomes Among Patients Treated With Clopidogrel Predominantly for PCI: A Meta-Analysis

CONTENT Clopidogrel, one of the most commonly prescribed medications, is a prodrug requiring CYP450 biotransformation. Data suggest its pharmacologic effect varies based on CYP2C19 genotype, but there is uncertainty regarding the clinical risk imparted by specific genotypes. OBJECTIVE To define the risk of major adverse cardiovascular outcomes among carriers of 1 (≈ 26% prevalence in whites) and carriers of 2 (≈ 2% prevalence in whites) reduced-function CYP2C19 genetic variants in patients treated with clopidogrel. DATA SOURCES AND STUDY SELECTION A literature search was conducted (January 2000-August 2010) in MEDLINE, Cochrane Database of Systematic Reviews, and EMBASE. Genetic studies were included in which clopidogrel was initiated in predominantly invasively managed patients in a manner consistent with the current guideline recommendations and in which clinical outcomes were ascertained. DATA EXTRACTION Investigators from 9 studies evaluating CYP2C19 genotype and clinical outcomes in patients treated with clopidogrel contributed the relevant hazard ratios (HRs) and 95% confidence intervals (CIs) for specific cardiovascular outcomes by genotype. RESULTS Among 9685 patients (91.3% who underwent percutaneous coronary intervention and 54.5% who had an acute coronary syndrome), 863 experienced the composite end point of cardiovascular death, myocardial infarction, or stroke; and 84 patients had stent thrombosis among the 5894 evaluated for such. Overall, 71.5% were noncarriers, 26.3% had 1 reduced-function CYP2C19 allele, and 2.2% had 2 reduced-function CYP2C19 alleles. A significantly increased risk of the composite end point was evident in both carriers of 1 (HR, 1.55; 95% CI, 1.11-2.17; P = .01) and 2 (HR, 1.76; 95% CI, 1.24-2.50; P = .002) reduced-function CYP2C19 alleles, as compared with noncarriers. Similarly, there was a significantly increased risk of stent thrombosis in both carriers of 1 (HR, 2.67; 95% CI, 1.69-4.22; P < .0001) and 2 (HR, 3.97; 95% CI, 1.75-9.02; P = .001) CYP2C19 reduced-function alleles, as compared with noncarriers. CONCLUSION Among patients treated with clopidogrel for percutaneous coronary intervention, carriage of even 1 reduced-function CYP2C19 allele appears to be associated with a significantly increased risk of major adverse cardiovascular events, particularly stent thrombosis.

Management of antithrombotic therapy in atrial fibrillation patients presenting with acute coronary syndrome and/or undergoing percutaneous coronary or valve interventions: a joint consensus document of the European Society of Cardiology Working Group on Thrombosis, European Heart Rhythm Association (EHRA), European Association of Percutaneous Cardiovascular Interventions (EAPCI) and European Association of Acute Cardiac Care (ACCA) endorsed by the Heart Rhythm Society (HRS) and Asia-Pacific Heart Rhythm Society (APHRS)

Atrial fibrillation (AF) confers a substantial risk of mortality and morbidity from stroke and thrombo-embolism, and this common cardiac arrhythmia represents a major healthcare burden in Europe.1 Stroke prevention is central to the management of AF patients, with the 2012 focused update of the European Society of Cardiology (ESC) guidelines2 recommending oral anticoagulation (OAC) using well-controlled adjusted dose vitamin K antagonists (VKAs, e.g. warfarin) or non-VKA oral anticoagulants (NOACs, previously referred to as new or novel OACs3) for patients with AF and ≥1 stroke risk factor(s). Also, these guidelines strongly advocate a clinical practice shift so that the initial decision step now is the identification of ‘truly low risk’ patients, essentially those aged <65 years without any stroke risk factor (both male and female), who do not need any antithrombotic therapy.2 The ESC guidelines also recommend the use of the CHA2DS2-VASc score4 for stroke risk assessment, and define ‘low-risk’ patients as those with a CHA2DS2-VASc score = 0 (males) or score = 1 (females). Subsequent to this initial step of identifying the low-risk patients, effective stroke prevention (which is essentially OAC) can then be offered to AF patients with ≥1 stroke risk factor(s), with treatment decisions made in consultation with patients and incorporating their preferences. In everyday clinical practice, over 80% of all patients with AF have an indication for OAC, and vascular disease co-exists in ∼30% of them.5–7 With an estimated prevalence of AF of 1–2% and ∼20% of these requiring percutaneous cardiovascular interventions over time,8 ∼1–2 million AF patients in Europe who are …

Long-term dual antiplatelet therapy for secondary prevention of cardiovascular events in the subgroup of patients with previous myocardial infarction: a collaborative meta-analysis of randomized trials

AIMS Recent trials have examined the effect of prolonged dual antiplatelet therapy (DAPT) in a variety of patient populations, with heterogeneous results regarding benefit and safety, specifically with regard to cardiovascular and non-cardiovascular mortality. We performed a meta-analysis of randomized trials comparing more than a year of DAPT with aspirin alone in high-risk patients with a history of prior myocardial infarction (MI). METHODS AND RESULTS A total of 33 435 patients were followed over a mean 31 months among one trial of patients with prior MI (63.3% of total) and five trials with a subgroup of patients that presented with, or had a history of, a prior MI (36.7% of total). Extended DAPT decreased the risk of major adverse cardiovascular events compared with aspirin alone (6.4 vs. 7.5%; risk ratio, RR 0.78, 95% confidence intervals, CI, 0.67-0.90; P = 0.001) and reduced cardiovascular death (2.3 vs. 2.6%; RR 0.85, 95% CI 0.74-0.98; P = 0.03), with no increase in non-cardiovascular death (RR 1.03, 95% CI 0.86-1.23; P = 0.76). The resultant effect on all-cause mortality was an RR of 0.92 (95% CI 0.83-1.03; P = 0.13). Extended DAPT also reduced MI (RR 0.70, 95% CI 0.55-0.88; P = 0.003), stroke (RR 0.81, 95% CI 0.68-0.97; P = 0.02), and stent thrombosis (RR 0.50, 95% CI 0.28-0.89; P = 0.02). There was an increased risk of major bleeding (1.85 vs. 1.09%; RR 1.73, 95% CI 1.19-2.50; P = 0.004) but not fatal bleeding (0.14 vs. 0.17%; RR 0.91, 95% CI 0.53-1.58; P = 0.75). CONCLUSION Compared with aspirin alone, DAPT beyond 1 year among stabilized high-risk patients with prior MI decreases ischaemic events, including significant reductions in the individual endpoints of cardiovascular death, recurrent MI, and stroke. Dual antiplatelet therapy beyond 1 year increases major bleeding, but not fatal bleeding or non-cardiovascular death.

Low Molecular Weight Heparin After Mechanical Heart Valve Replacement

BACKGROUND Patients with mechanical heart valves require life-long anticoagulation. We report here the first large and comparative series of consecutive patients anticoagulated with low molecular weight heparin (LMWH) after mechanical heart valve replacement. METHODS AND RESULTS In this comparative, nonrandomized study, 208 consecutive patients who underwent a single or double heart valve replacement with mechanical prostheses were anticoagulated subcutaneously with unfractionated heparin (UH) in the first period (n=106) and LMWH in the second phase (n=102) of the study. Baseline characteristics were similar in the 2 groups. The mean durations of UH and LMWH treatments were 13.6+/-0.5 and 14.1+/-0.6 days, respectively (not significant). On the second day of treatment, 87% of patients treated with LMWH had an anti-Xa activity within the range of efficacy (0.5 to 1 IU/mL), but only 9% of UH-treated patients had an activated partial-thromboplastin time value within the therapeutic range (1.5 to 2.5 times control, P<0.0001 between the 2 groups). On the last day of prescription, all LMWH-treated patients had anti-Xa activity above 0.5 IU/mL, but 19% were above 1 IU/mL. In the UH group, 27% of patients had an activated partial-thromboplastin time above 1.5 times control, but 62% were overanticoagulated. Two major bleedings occurred in each group, and one stroke occurred in the UH group. CONCLUSIONS In this first comparative study, anticoagulation with LMWHs after mechanical heart valve replacement appears feasible, provides adequate biological anticoagulation, and compares favorably with UH anticoagulation. Randomized studies are now needed to further evaluate this new therapeutic approach.

A unique, low dose of intravenous enoxaparin in elective percutaneous coronary intervention

OBJECTIVES This study was designed to examine a unique and low dose of intravenous enoxaparin in elective percutaneous coronary intervention (PCI) that would be applicable to an unselected population regardless of age, weight, renal function, or use of glycoprotein IIb/IIIa inhibitors. BACKGROUND There is limited experience of anticoagulation using intravenous (IV) low-molecular-weight heparin in PCI, which has been obtained with high doses causing elevated anticoagulation levels and delayed sheath withdrawal. METHODS A total of 242 consecutive patients undergoing elective PCI were treated with a single IV bolus of enoxaparin (0.5 mg/kg), and 26% of patients (n = 64) also received eptifibatide. Sheaths were removed immediately after the procedure in patients treated with enoxaparin only, and 4 h after the procedure in those also treated with eptifibatide. RESULTS A peak anti-Xa >0.5 IU/ml was obtained in 97.5% of the population, and 94.6% of patients had their peak anti-Xa level in the predefined target range of 0.5 to 1.5 IU/ml. Advanced age, renal failure, being overweight, and eptifibatide use did not alter the anticoagulation profile. At one-month follow-up, six patients (2.5%) had died, had a myocardial infarction, or undergone an urgent revascularization; all the patients had an anti-Xa level >0.5 IU/ml during PCI. Patients without an ischemic event and without a creatine kinase rise, but with a detectable troponin release in the next 24 h of PCI (>2 microg/ml, n = 21), had similar anti-Xa levels as those without troponin elevation. There were one major and three minor bleeding events that were not associated with anti-Xa overshoot. CONCLUSIONS Low-dose (0.5 mg/kg) IV enoxaparin allows a prespecified target level of anticoagulation (anti-Xa >0.5 IU/ml) in the vast majority of patients undergoing PCI, appears to be safe and effective, allows immediate sheath removal when used alone, and does not require dose adjustment when used with eptifibatide.

Effects of various anticoagulant treatments on von Willebrand factor release in unstable angina.

OBJECTIVES We tested the hypothesis that different anticoagulant treatments may produce different platelet effects and von Willebrand factor (vWf) release in unstable angina. BACKGROUND The early increase of vWf has been reported to be a risk factor for adverse outcome in unstable angina. Anticoagulant drugs play a key role in stabilization of unstable angina, but they may not have the same efficacy and the same effects on acute vWf release. METHODS We studied 154 patients enrolled in several clinical trials testing four different anticoagulant treatments in unstable angina or non-Q-wave myocardial infarction. Patients were treated during at least 48 h by either intravenous unfractionated heparin, one of two different low molecular weight heparins (enoxaparin or dalteparin) or the direct thrombin inhibitor PEG-hirudin. All patients received aspirin but no Ib/IIIa inhibitors. RESULTS The release of vWf over the first 48 h (delta vWf) did not relate to the baseline clinical characteristics. At 30 days of follow-up, delta vWf was sevenfold higher in patients with an end point (death, myocardial infarction, revascularization) than in patients free of events (+53 +/-7% vs. +7 +/-14%, p = 0.004). The same trend was present for each component of the composite end point with the highest levels for one-month mortality (+87 +/- 32% vs. +26 +/- 8%, p = 0.09). The vWf values did not increase over 48 h in patients receiving either enoxaparin or PEG-hirudin (+10 +/- 9% and -5 +/- 20%, respectively). A serious rise ofvWf was measured in unfractionated heparin-treated patients (+87 +/- 11%), which differed significantly from the enoxaparin group (p = 0.0006) and PEG-hirudin group (p < 0.0001). In dalteparin-treated patients, delta vWf was elevated (+48 +/- 8%) and did not differ from the unfractionated heparin group (NS). CONCLUSIONS We confirm that, in unstable angina patients, a rise of vWf over the first 48 h is associated with an impaired outcome at 30 days. Moreover, the four different anticoagulant treatments tested here do not provide the same protection with regards to vWf release, which may have important prognostic implications and explain different results observed in recent clinical trials.

Open issues in transcatheter aortic valve implantation. Part 1: patient selection and treatment strategy for transcatheter aortic valve implantation

An exponential increase in the use of transcatheter aortic valve implantation (TAVI) in patients with severe aortic stenosis has been witnessed over the recent years. The current article reviews different areas of uncertainty related to patient selection. The use and limitations of risk scores are addressed, followed by an extensive discussion on the value of three-dimensional imaging for prosthesis sizing and the assessment of complex valve anatomy such as degenerated bicuspid valves. The uncertainty about valvular stenosis severity in patients with a mismatch between the transvalvular gradient and the aortic valve area, and how integrated use of echocardiography and computed tomographic imaging may help, is also addressed. Finally, patients referred for TAVI may have concomitant mitral regurgitation and/or coronary artery disease and the management of these patients is discussed.

Open issues in transcatheter aortic valve implantation. Part 2: procedural issues and outcomes after transcatheter aortic valve implantation

This article provides an overview on procedure-related issues and uncertainties in outcomes after transcatheter aortic valve implantation (TAVI). The different access sites and how to select them in an individual patient are discussed. Also, the occurrence and potential predictors of aortic regurgitation (AR) after TAVI are addressed. The different methods to quantify AR are reviewed, and it appears that accurate and reproducible quantification is suboptimal. Complications such as prosthesis-patient mismatch and conduction abnormalities (and need for permanent pacemaker) are discussed, as well as cerebrovascular events, which emphasize the development of optimal anti-coagulative strategies. Finally, recent registries have shown the adoption of TAVI in the real world, but longer follow-up studies are needed to evaluate the outcome (but also prosthesis durability). Additionally, future studies are briefly discussed, which will address the use of TAVI in pure AR and lower-risk patients.

Clinical outcomes according to permanent discontinuation of clopidogrel or placebo in the CHARISMA trial

BACKGROUND Late discontinuation of clopidogrel after an acute coronary syndrome or stent placement may be associated with a clinical rebound effect. AIMS To describe the characteristics and evolution of patients non-compliant to study drug in the prospective, randomized, double-blind CHARISMA trial. METHODS Of 15,603 patients aged 45 or older years with established atherothrombotic disease (coronary artery disease, stroke, peripheral arterial disease) or multiple cardiovascular risk factors, 2999 permanently interrupted (withdrawers) study drug (clopidogrel or placebo) during follow-up. The primary endpoint was first occurrence since randomization of myocardial infarction, stroke or cardiovascular death. RESULTS Withdrawers displayed a higher risk profile and rates of death/myocardial infarction/stroke (13.5% versus 5.6%; hazard ratio [HR]: 3.18; 95% confidence interval [CI]: 3.05-3.32; p<0.001) and severe bleeding (4.9% versus 0.7%; odds ratio [OR]: 7.42; 95% CI: 5.67-9.70; p<0.001) versus non-withdrawers. Death/myocardial infarction/stroke occurred after an average of 228 days (95% CI: 197-258) and was less frequent in patients assigned to clopidogrel versus placebo (9.7% versus 11.9%; HR: 0.80; 95% CI: 0.64-1.00; p=0.051); the rate of severe bleeding was the same (4.0% versus 4.3%; OR: 0.92; 95% CI: 0.65-1.32; p=0.66). Among withdrawers, initial clopidogrel treatment was an independent correlate of survival (HR: 0.74, 95% CI: 0.59-0.93; p=0.011), but not severe bleeding (OR: 0.94; 95% CI: 0.65-1.35; p=0.74). Kaplan-Meier curves for the primary endpoint suggested no rebound effect or disease reactivation after discontinuation of clopidogrel compared with placebo. CONCLUSIONS Patients who stopped medication had increased rates of ischaemic and bleeding events and mortality. Patients initially on clopidogrel had fewer ischaemic events than those on placebo; discontinuation was not associated with any clinically detectable rebound effect.