Franck Paganelli

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.

Adjusted Clopidogrel Loading Doses According to Vasodilator-Stimulated Phosphoprotein Phosphorylation Index Decrease Rate of Major Adverse Cardiovascular Events in Patients With Clopidogrel Resistance A Multicenter Randomized Prospective Study

OBJECTIVES This study evaluates the clinical impact of adjusting the loading dose of clopidogrel according to vasodilator-stimulated phosphoprotein (VASP) index in patients with clopidogrel resistance undergoing percutaneous coronary intervention (PCI). BACKGROUND Clopidogrel resistance plays a key role in ischemic recurrence after PCI. In vitro tests of clopidogrel resistance can accurately predict major adverse cardiac events after PCI. METHODS In this prospective, randomized, multicenter study, clopidogrel resistance was defined as a VASP index of more than 50% after a 600-mg loading dose. Patients with clopidogrel resistance undergoing coronary stenting were randomized to a control group or to the VASP-guided group, in which patients received additional bolus clopidogrel to decrease the VASP index below 50%. RESULTS A total of 162 patients were included. The control (n = 84) and VASP-guided groups (n = 78) had similar demographic, clinical, and biological characteristics. In the VASP-guided group, dose adjustment was efficient in 67 patients (86%) and VASP index was significantly decreased (from 69.3 +/- 10 to 37.6 +/- 13.8; p < 0.001). Eight major adverse cardiac events (5%) were recorded during the 1-month follow-up, with a significantly lower rate in the VASP-guided group compared with the control group (0% vs. 10%; p = 0.007). There was no difference in the rate of major and minor bleeding (5% vs. 4%; p = 1). CONCLUSIONS This is the first study to suggest that adjusting the clopidogrel loading dose according to platelet monitoring using the VASP index is safe and may significantly improve the clinical outcome after PCI in patients with clopidogrel resistance despite a first 600-mg loading dose.

Vasodilator-stimulated phosphoprotein phosphorylation analysis prior to percutaneous coronary intervention for exclusion of postprocedural major adverse cardiovascular events.

Summary.  Background: Despite dual antiplatelet therapy, the rate of major adverse cardiovascular events (MACE) after percutaneous coronary angioplasty remains high. Studies have shown interindividual variations in response to clopidogrel. Furthermore, there is an apparent link between clinical outcomes and clopidogrel resistance. Objectives: To investigate the value of platelet reactivity index (PRI), assessed by vasodilator‐stimulated phosphoprotein (VASP) phosphorylation analysis, for predicting MACE after percutaneous coronary intervention (PCI) with stent implantation.Methods: A prospective monocentric study was performed on 144 patients undergoing PCI. PR was evaluated by VASP phosphorylation analysis 24 h after they received a 300‐mg loading dose of clopidogrel. MACE were recorded during a 6‐month follow‐up. Patients were divided into quintiles according to PRI, as assessed by VASP analysis. The receiver operating characteristic (ROC) curve served to determine the optimal cut‐off value of VASP analysis to detect MACE.Results: Of the 144 patients, 34% had stable angina pectoris, 40% silent ischemia, and 26% low‐risk non‐ST‐segment elevation acute coronary syndrome. During the follow‐up, 21 MACE were observed. Patients in quintile 1 of VASP analysis had a significantly lower risk of MACE as compared with those among the four higher quintiles (0 vs. 21, P < 0.01). ROC curve analysis of VASP showed an optimal cut‐off value of 50% PR to exclude MACE. The negative predictive value of the test was 100%.Conclusions: VASP phosphorylation analysis can evaluate the individual response to clopidogrel loading dose prior to PCI and predict postprocedural MACE.

Tailored clopidogrel loading dose according to platelet reactivity monitoring to prevent acute and subacute stent thrombosis.

Stent thrombosis remains a significant pitfall of percutaneous coronary intervention (PCI). A recent trial observed that an adjusted loading dose (LD) of clopidogrel according to platelet monitoring decreases the rate of major adverse cardiovascular events after PCI. We investigated if such a strategy of a tailored clopidogrel LD according to platelet reactivity monitoring could decrease the rate of stent thrombosis. This multicenter prospective randomized study included 429 patients with a low clopidogrel response after a 600-mg LD undergoing PCI. Patients were randomized to a control group (n = 214) and to a vasodilator-stimulated phosphoprotein (VASP)-guided group (n = 215). In the VASP-guided group, patients received up to 3 additional 600-mg LDs of clopidogrel to obtain a VASP index <50% before PCI. The primary end point was the rate of stent thrombosis at 1 month. Secondary end points were rates of major adverse cardiovascular events and bleeding. Patients in the 2 groups had a high body mass index and were often diabetic (control vs VASP-guided group 28 +/- 5.1 vs 27.9 +/- 4.7 kg/m(2), p = 0.8, and 39% vs 33%, p = 0.2, respectively). PCI was performed in most patients for acute coronary syndrome in the 2 groups (52.3% vs 50.7%, p = 0.8). Despite a 2,400-mg LD of clopidogrel, 8% of patients in the VASP-guided group remained low responders. The rate of stent thrombosis was significantly lower in the VASP-guided group (0.5% vs 4.2%, p <0.01). The rate of major adverse cardiovascular events was also higher in the control group (8.9% vs 0.5%, p <0.001). There was no difference in the rate of bleeding (2.8% vs 3.7%, p = 0.8). In conclusion, a tailored clopidogrel LD according to platelet reactivity monitoring decreases the rate of early stent thrombosis after PCI without increasing bleeding.

High on-treatment platelet reactivity after prasugrel loading dose and cardiovascular events after percutaneous coronary intervention in acute coronary syndromes.

OBJECTIVES The aim of this study was to investigate the relationship between platelet reactivity (PR) after a loading dose (LD) of prasugrel and thrombotic events. BACKGROUND Post-treatment PR has been shown to be strongly associated with the occurrence of major adverse cardiac events (MACE) after percutaneous coronary intervention (PCI) in the clopidogrel era. Prasugrel is a new P2Y(12)-adenosine diphosphate receptor with a higher potency on PR. METHODS A prospective multicenter study included patients who underwent successful PCI for acute coronary syndromes and received prasugrel therapy. Vasodilator-stimulated phosphoprotein (VASP) index was measured after the prasugrel LD. High on-treatment PR was defined as a VASP index ≥50%. MACE included cardiovascular death, myocardial infarction, and definite stent thrombosis at 1 month. RESULTS Three hundred one patients were enrolled. The mean VASP index after 60 mg of prasugrel was 34.3 ± 23.1%. High on-treatment PR was observed in 76 patients (25.2%). Patients experiencing thrombotic events after PCI had significantly higher VASP indexes compared with those free of events (64.4 ± 14.4% vs. 33.4 ± 22.7%; range: 51% to 64% and 5% to 47.6%, respectively; p = 0.001). Kaplan-Meier analysis comparing good responders and patients with high on-treatment PR demonstrated a significantly higher rate of MACE in patients with suboptimal PR inhibition (log-rank p < 0.001). Receiver-operating characteristic curve analysis found a cutoff value of 53.5% of the VASP index to predict thrombotic events at 1 month (r = 0.86, p < 0.001). Patients with minor or major Thrombolysis In Myocardial Infarction unrelated to coronary artery bypass grafting bleeding and those without had similar VASP indexes (30 ± 17.8% vs. 34.3 ± 23%, p = 0.70). CONCLUSIONS Despite the use of prasugrel, a significant number of patients undergoing PCI in the setting of acute coronary syndromes do not achieve optimal PR inhibition. Such patients have a higher risk for MACE after PCI.

Low-Energy Cardioversion of Spontaneous Atrial Fibrillation Immediate and Long-term Results

BACKGROUND Recent studies have suggested that induced atrial fibrillation (AF) could be successfully terminated by using a two-catheter electrode system and low energy (< 400 V). This study evaluated the efficacy and safety of low-energy cardioversion in spontaneous chronic and paroxysmal AF. METHODS AND RESULTS Forty-two consecutive patients with spontaneous AF underwent low-energy electrical cardioversion. AF was chronic (> or = 1 month) with a mean duration of 9 +/- 19 months in 28 patients (group I) or paroxysmal with a history of recurrent attacks and a mean duration of the present episode of 7 +/- 16 days in 14 patients (group II). An underlying heart disease was present in 28 patients. A 3/3-ms biphasic shock was delivered between catheters positioned in the right atrium and the coronary sinus in 32 patients. In 10 patients, the left pulmonary artery branch was used. The catheters were connected to a custom external defibrillator. The shocks were synchronized to the R wave. Following a test shock of 60 V, the energy was increased in 40-V steps until a maximum of 400 V or restoration of sinus rhythm. Sinus rhythm was restored in 22 of the 28 patients (78%) of group I by using a mean leading-edge voltage of 297 +/- 57 V (mean energy 3.3 +/- 1.3 J) and in 11 of 14 patients (78%) of group II by using a mean leading-edge voltage of 223 +/- 41 V (mean energy, 1.8 +/- 0.7 J). The energy required for terminating chronic AF was significantly (P < .001) higher than that required for terminating paroxysmal AF. Among the other variables studied, the duration of AF significantly affected the successful voltage. Ventricular proarrhythmia occurred in 1 patient with atrial flutter due to an unsynchronized shock. Of the 22 patients of group I in whom sinus rhythm was restored, 14 (63%) remained in sinus rhythm with a mean follow-up of 9 +/- 3 months. Pain level showed a good correlation with increasing voltage. However, a marked inter-individual variation was noted. CONCLUSIONS Atrial defibrillation using low energy between two intracardiac catheters with an electrical field between the right and left atria and the protocol used is feasible in patients with persistent spontaneous AF. The technique is safe provided synchronization to the R wave is achieved. A low recurrence rate of AF was seen in patients in whom sinus rhythm was restored.

Clopidogrel Loading Dose Adjustment According to Platelet Reactivity Monitoring in Patients Carrying the 2C19*2Loss of Function Polymorphism

OBJECTIVES We aimed to investigate the biological impact of a tailored clopidogrel loading dose (LD) according to platelet reactivity monitoring in carriers of the cytochrome (CYP) 2C19*2 loss-of-function polymorphism undergoing percutaneous coronary intervention for an acute coronary syndromes. BACKGROUND CYP2C19*2 polymorphism is associated with reduced clopidogrel metabolism and a worse prognosis after percutaneous coronary intervention. METHOD A prospective multicenter study enrolling 411 patients with non-ST-segment elevation acute coronary syndrome undergoing percutaneous coronary intervention was performed. Platelet reactivity was measured using the vasodilator-stimulated phosphoprotein (VASP) index, and a cutoff value of ≥ 50% was used to define high on-treatment platelet reactivity (HTPR). The genetic polymorphism of CYP2C19 was determined by allele-specific polymerase chain reaction. In patients carrying CYP2C19*2 and exhibiting HTPR after a first 600-mg LD of clopidogrel, dose adjustment was performed by using up to 3 additional 600 mg LDs to obtain a VASP index <50%. RESULTS One hundred thirty-four patients (35.3%) carried at least one 2C19*2 allele (11 homozygotes [2.7%] and 123 heterozygotes [32.6%]). The VASP index in these patients was significantly higher than in homozygotic patients for the wild-type alleles (61.7 ± 18.4% vs. 49.2 ± 24.2%; p < 0.001). Of the 134 carriers of the loss-of-function polymorphism, 103 were considered to have HTPR. After a second clopidogrel LD, the VASP index was significantly decreased in these patients (69.7 ± 10.1% vs. 50.6 ± 17.6%; p < 0.0001). Finally, dose adjustment according to platelet reactivity monitoring, enabled 88% of 2C19*2 carriers exhibiting HTPR to reach a VASP index <50%. CONCLUSIONS Increased and tailored clopidogrel loading dose according to platelet reactivity monitoring overcome HTPR in carriers of the loss-of-function CYP2C19*2 polymorphism.

Relationship between post-treatment platelet reactivity and ischemic and bleeding events at 1-year follow-up in patients receiving prasugrel

Summary.  Background:  Post‐treatment platelet reactivity (PR) is associated with ischemic and bleeding events in patients receiving P2Y12 receptor antagonists.

Role of Endogenous Adenosine as a Modulator of Syncope Induced During Tilt Testing

Background—Previous reports that used head-up tilt testing and adenosine administration have suggested that adenosine may be an important endogenous mediator that may trigger a vasovagal response in susceptible patients. However, little is known regarding endogenous adenosine plasma levels (APLs) during vasovagal syncope provoked by tilt testing. The aim of this study was to determine whether APLs differ in patients with a positive head-up tilt test compared with those with a negative test and whether APLs are modified during tilt-induced vasovagal syncope. Methods and Results—APLs (mean±SEM) were measured during head-up tilt test in 26 patients who presented with unexplained syncope. In the 15 patients with a negative test, APLs were 0.39±0.03 &mgr;mol/L at baseline, 0.22±0.03 &mgr;mol/L immediately after tilting, and 0.44±0.03 &mgr;mol/L after 45 minutes. APLs were significantly higher in the 11 patients with a positive test (2.66±0.67 &mgr;mol/L at baseline and 3.22±0.85 &mgr;mol/L immediately after tilting) than in those with a negative test. During tilt testing–induced syncope, APLs increased to reach 4.03±0.66 &mgr;mol/L (ie, a 52% increase compared with baseline levels;P <0.02). Furthermore, we observed that the higher the APL during syncope, the shorter the time to appearance of symptoms. Conclusions—This study showed that APLs were higher in patients with a positive tilt test than in patients with a negative test and that they increased during tilt testing–induced syncope. These observations suggest that adenosine release may be involved in the triggering mechanism of syncope induced during tilt testing.

Endothelial injury induced by coronary angioplasty triggers mobilization of endothelial progenitor cells in patients with stable coronary artery disease1

Despite the wider use of drug-eluting stents, the rate of complications following angioplasty, mainly stent thrombosis and in-stent restenosis, is still limiting [1]. These complications are the consequences of endothelial injury and may depend on the efficiency of the healing process for the re-establishment of the endothelial monolayer. This balance between damage and repair is therefore of critical importance in determining angioplasty outcomes [2]. Circulating endothelial cells (CEC) can be used to monitor both functional and physical endothelial integrity [3]. They are non-hematopoietic cells, originated from sloughing of the injured vessel wall. These cells are defined by the expression of endothelial markers, the absence of leukocyte and immaturitymarkers, and the lack of proliferative potential in vitro [3]. CEC are found in very low concentration in healthy subjects [4] but increased numbers are described in various cardiovascular clinical settings with significant diagnosis and prognostic value [5–9]. Repair of an injured endothelium has been recently shown to involve circulating endothelial progenitor cells (EPC). These cells are defined as bonemarrowderived circulating cells with an immature endothelial phenotype, a high clonogenic potential in vitro and a specific capacity to contribute to angiogenesis in vivo [10,11]. The baseline number of circulating EPC depends on numerous factors among which are coronary artery disease severity, cardiovascular risk factors, and aging [12,13]. The main triggers of EPC mobilization from bone marrow to peripheral blood are ischemia and vascular trauma [14–16]. Although experimental models of vascular injury have suggested that exogenous EPC could play a critical role in the restoration of the endothelial lining [17–19], whether endothelial injury induced by coronary angioplasty is a sufficient stimulus to trigger EPC mobilization in coronary artery disease (CAD) patients is still unknown. We investigated the effect of coronary angioplasty on EPC levels in patients with CADand determine the relationship with the endothelial damage assessed by CEC counts. Patients with stable angina with need for scheduled angioplasty on a native coronary were enrolled after an informed consent was obtained. Exclusion criteria were acute coronary syndromes (ACS) within the two previous weeks, elevated preprocedural troponin Ic (cTnI), concurrent illness that could affect progenitor cell count. Coronary angioplasty and sirolimuscoated stent implantation were performed according to institutional standards, using a balloon inflation time of 30 s at 20 atmospheres. Blood samples were obtained before angioplasty (pre-precutaneous coronary intervention [PCI]), immediately after the end of the procedure (post-PCI), then 6, 24, 48 h and 7 days after PCI. CEC were counted using CD146-based immunomagnetic separation as previously described [4]. Circulating hematopoietic progenitor cells (HPC) were analyzed using flow cytometry (Epics XL Cytometer; Beckman Coulter, Villepinte, France) after staining of whole blood with fluorescein isothiocyanate (FITC)-labeled monoclonal mouse antihuman CD45 antibody, phycoerythrin (PE)-labeled monoclonal mouse antihuman CD34 antibody and 7AAD (Stemkit ; Beckman Coulter). Absolute numbers of HPC lL were determined using calibration beads according to manufacturer’s instructions. The number of circulating EPC was determined using a colony-forming assay according to method ofHill et al. [12]. Results were expressed in number of CFU-EC per 10 cells. Correspondence: Françoise Dignat-George, INSERM UMR 608, UFR de Pharmacie, 27 Boulevard Jean Moulin, 13385 Marseille cedex 5, France. Tel.: + 33 4 91 83 56 00; fax: + 33 4 91 83 56 02; e-mail: dignat@ pharmacie.univ-mrs.fr