Point-of-care genetic profiling and/or platelet function testing in acute coronary syndrome.

Our aim was to demonstrate that the sequential use of the Verigene® rapid CYP2C19 test for genetic profiling and the VerifyNowTM bedside test for platelet function measurement in ACS patients may optimise P2Y12 inhibition. "Rapid" (CYP2C19*1/*1 or CYP2C19*17 carriers, n=211) and "slow" metabolisers (CYP2C19*2 carriers, n=58) were first put on clopidogrel and prasugrel for ≥ 2 weeks, respectively. Patients with low platelet reactivity (PRU<30) on prasugrel or high platelet reactivity (>208 PRU) on clopidogrel were then switched to clopidogrel and prasugrel, respectively. Our objectives were (i) to demonstrate that the proportion of "rapid" metabolisers on 75 mg of clopidogrel within 30-208 (PRU) of P2Y12 inhibition is non-inferior to "slow" metabolisers on prasugrel 10 mg and (ii) to evaluate the same end-point after switching drugs. The proportion of "rapid" and "slow" metabolisers within 30-208 PRU of P2Y12 inhibition was 71% and 56.9%, respectively, an absolute difference of +14.1% (95% CI, -0.05% to 28.28%) with a non-inferiority margin greater than the predefined margin of -10%. Among patients out of target, all but one "slow" metabolisers displayed low-on prasugrel platelet reactivity while the majority of "rapid" metabolisers (68%) displayed high-on clopidogrel platelet reactivity. After switching, the proportion of patients within 30-208 PRU of P2Y12 inhibition was 83.6% and 79.3% in "rapid" and "slow" metabolisers, respectively (+4.3%, 95% CI -7.3% to 15.9%). In conclusion, this study demonstrates a loose relationship between genotype and platelet function phenotype approaches but that they are complementary to select prasugrel or clopidogrel MD in stented ACS patients.

Pretest probability of a normal echocardiography: validation of a simple and practical algorithm for routine use.

BACKGROUND: Management of increased referrals for transthoracic echocardiography (TTE) examinations is a challenge. Patients with normal TTE examinations take less time to explore than those with heart abnormalities. A reliable method for assessing pretest probability of a normal TTE may optimize management of requests. AIM: To establish and validate, based on requests for examinations, a simple algorithm for defining pretest probability of a normal TTE. METHODS: In a retrospective phase, factors associated with normality were investigated and an algorithm was designed. In a prospective phase, patients were classified in accordance with the algorithm as being at high or low probability of having a normal TTE. RESULTS: In the retrospective phase, 42% of 618 examinations were normal. In multivariable analysis, age and absence of cardiac history were associated to normality. Low pretest probability of normal TTE was defined by known cardiac history or, in case of doubt about cardiac history, by age>70 years. In the prospective phase, the prevalences of normality were 72% and 25% in high (n=167) and low (n=241) pretest probability of normality groups, respectively. The mean duration of normal examinations was significantly shorter than abnormal examinations (13.8 ± 9.2 min vs 17.6 ± 11.1 min; P=0.0003). CONCLUSION: A simple algorithm can classify patients referred for TTE as being at high or low pretest probability of having a normal examination. This algorithm might help to optimize management of requests in routine practice.

Impact of red blood cell transfusion on platelet aggregation and inflammatory response in anemic coronary and noncoronary patients: the TRANSFUSION-2 study (impact of transfusion of red blood cell on platelet activation and aggregation studied with flow cytometry use and light transmission aggregometry).

OBJECTIVES: This study sought to determine whether red blood cell (RBC) transfusion increases in vivo platelet aggregation and inflammation in coronary and noncoronary patients. BACKGROUND: RBC transfusion increases in vitro platelet activation and aggregation in healthy volunteers, providing a possible explanation for the increase in recurrent ischemic events and mortality reported after RBC transfusion in patients with acute coronary syndromes (ACS). METHODS: Platelet reactivity was measured before and after RBC transfusion in 61 patients (33 with ACS patients and 28 without ACS). Relative changes between baseline and post-transfusion measurements of maximal and residual platelet aggregation were considered with different agonists as well as changes in vasodilator-stimulated phosphoprotein platelet reactivity index and P-selectin expression. Inflammatory and thrombotic biomarkers were also measured before and after transfusion. RESULTS: After RBC transfusion, platelet reactivity was increased when measured using adenosine diphosphate-induced light transmission aggregometry (11.6% relative increase in maximal platelet aggregation, p = 0.004; 10.8% increase in residual platelet aggregation, p = 0.005) and vasodilator-stimulated phosphoprotein platelet reactivity index (20.7% relative increase, p = 0.002), and there was a nonsignificant trend toward an increase in P-selectin expression. Similar results were found with the nonspecific agonist thrombin receptor-activated peptide (relative increases of 11.7% for maximal platelet aggregation, p = 0.04, and 12.7% for residual platelet aggregation, p = 0.02) but not with collagen or arachidonic acid agonists. There were no significant differences in inflammatory and thrombotic biomarkers before and after transfusion. CONCLUSIONS: After RBC transfusion, there is an increase in platelet reactivity, especially with tests measuring the adenosine diphosphate-P2Y12 receptor pathway, without significant variations in inflammatory or thrombotic biomarkers. This in vivo effect may account for the excess of ischemic events observed in the context of patients with ACS treated using percutaneous coronary intervention and P2Y12 inhibitors.

Switching acute coronary syndrome patients from prasugrel to clopidogrel.

OBJECTIVES: This study sought to assess the consequences of switching prasugrel to clopidogrel on platelet inhibition and clinical outcomes after an acute coronary syndrome (ACS). BACKGROUND: Many ACS patients are switched from prasugrel to clopidogrel within the recommended 1-year duration of treatment. METHODS: Platelet reactivity was measured with the VerifyNow P2Y(12) assay (Accumetrics, San Diego, California) in 300 ACS patients treated for 15 days with prasugrel 10 mg. Patients displaying low on-treatment platelet reactivity (LPR) and/or at high risk of bleeding were switched to clopidogrel 75 mg and tested again 15 days later. The rate of patients with high on-treatment platelet reactivity (HPR), P2Y(12) reaction units (PRU) >208, and LPR (PRU <0) were evaluated before and after the switch. Bleeding and ischemic events were also recorded. RESULTS: On a regimen of prasugrel 10 mg, the rate of patients with LPR was 45.6% (n = 137), whereas 4.3% (n = 13) had HPR. A group of 31 patients (10.3%) was switched to clopidogrel 75 mg, of whom 29 had LPR (93.5%) on a regimen of prasugrel. On-treatment platelet reactivity (PRU) increased from 14 ± 4 on a regimen of prasugrel to 155 ±15 on a regimen of clopidogrel (p = 0.0001), resulting in a much lower rate of patients with LPR (9.7%). The rate of patients with HPR increased from 0% with prasugrel to 29% (n = 9) with clopidogrel. The rate of minor bleeding decreased after the switch from 32.2% to 9.7%; p = 0.03. CONCLUSIONS: An LPR is frequent in patients treated with prasugrel 10 mg. Early switching from prasugrel 10 mg to clopidogrel 75 mg reduces the number of patients with LPR and minor bleeding events but unmasks a group of nonresponders to clopidogrel with unknown consequences on clinical outcomes.

Impact of transfer time on mortality in acute coronary syndrome with ST-segment elevation treated by angioplasty.

BACKGROUND: In primary percutaneous coronary intervention (pPCI), conflicting data exist on the relative importance of patient presentation time (time from symptom onset (SO) to first medical contact [FMC]) and transfer time (time from FMC to sheath insertion). OBJECTIVES: To evaluate the impact of transfer time on mortality in an unselected ST-elevation myocardial infarction (STEMI) population treated with pPCI. METHODS: In a well-organized urban network, using mobile intensive care units (MICU) whenever possible, the impact of transfer time on inhospital mortality was evaluated in 703 unselected consecutive STEMI patients transferred for pPCI. RESULTS: Our STEMI population included patients with cardiogenic shock (5.3%) and out-of-hospital cardiac arrest (3.7%). Longer transfer times were found to be associated with a stepwise increase in mortality ranging from 2.99% in the first quartile (Q1) up to 8.65% in the fourth quartile (Q4) (P=0.005). This result was noted in patients presenting early (≤2h of SO, 0.96% for Q1 vs. 9.8% for Q4, P=0.006) but not in late presenters (>2h of SO, 7.00% for Q1 vs. 7.8% for Q4, P=0.85). After adjustment for confounding variables such as the severity of patients, the relationship between mortality and transfer time was no longer apparent. CONCLUSIONS: In a well-organized urban network dedicated to pPCI, including unselected STEMI patients, transfer time does not appear to be a major contributor to mortality. The relationship of transfer time to mortality seems to be dependent on presentation time and patients' clinical severity.

Clinical, angiographic, and genetic factors associated with early coronary stent thrombosis.

CONTEXT: Despite dual antiplatelet therapy, stent thrombosis remains a devastating and unpredictable complication of percutaneous coronary intervention (PCI). OBJECTIVE: To perform a sequential analysis of clinical and genetic factors associated with definite early stent thrombosis. DESIGN, SETTING, AND PARTICIPANTS: Case-control study conducted in 10 centers in France between January 2007 and May 2010 among 123 patients undergoing PCI who had definite early stent thrombosis and DNA samples available, matched on age and sex with 246 stent thrombosis-free controls. MAIN OUTCOME MEASURE: Accuracy of early stent thrombosis prediction by 23 genetic variants. RESULTS: Among the 23 genetic variants investigated in 15 different genes, the significant determinants of early stent thrombosis were CYP2C19 metabolic status (adjusted odds ratio [OR], 1.99; 95% CI, 1.47-2.69), ABCB1 3435 TT genotype (adjusted OR, 2.16; 95% CI, 1.21-3.88), and ITGB3 PLA2 carriage (adjusted OR, 0.52; 95% CI, 0.28-0.95). Nongenetic independent correlates were acuteness of PCI (adjusted OR, 3.05; 95% CI, 1.54-6.07), complex lesions (American College of Cardiology/American Heart Association type C) (adjusted OR, 2.33; 95% CI, 1.40-3.89), left ventricular function less than 40% (adjusted OR, 2.25; 95% CI, 1.09-4.70), diabetes mellitus (adjusted OR, 1.82; 95% CI, 1.02-3.24), use of proton pump inhibitors (adjusted OR, 2.19; 95% CI, 1.29-3.75), and higher clopidogrel loading doses (adjusted OR, 0.73; 95% CI, 0.57-0.93). The discriminative accuracy of the clinical-only model was similar to that of a genetic-only model (area under the curve, 0.73 [95% CI, 0.67-0.78] vs 0.68 [95% CI, 0.62-0.74], respectively; P = .34). A combined clinical and genetic model led to a statistically significant increase in the discriminatory power of the model compared with the clinical-only model (area under the curve, 0.78 [95% CI, 0.73-0.83] vs 0.73 [95% CI, 0.67-0.78]; P = .004). CONCLUSIONS: This case-control study identified 3 genes (CYP2C19, ABCB1, and ITGB3) and 2 clopidogrel-related factors (loading dose and proton pump inhibitors) that were independently associated with early stent thrombosis. Future studies are needed to validate the prognostic accuracy of these risk factors in prospective cohorts.

FXIII-A Leu34 genetic variant in premature coronary artery disease: a genotype--phenotype case control study.

The FXIII-A Leu34 genetic variant increases and accelerates fibrin stabilisation; however, its association with premature coronary artery disease (CAD) and thrombotic events remains controversial. FXIII Val34Leu genotype was determined in 242 young individuals (<45 years old) who survived a myocardial infarction (MI) and 242 healthy controls matched for age and gender. We evaluated its effect on long-term clinical outcome defined as a composite of cardiovascular death, recurrent MI and urgent revascularisation. In addition, fibrin clot stiffness (elastic modulus or EM) and response to rt-PA-mediated fibrinolysis (fibrinolysis rate) were measured ex vivo using the Hemodyne analyser and confocal microscopy as surrogate endpoint. FXIII-A Leu34 genetic variant was not associated with premature CAD (adj. odds ratio 0.83 [0.49-1.4]) nor did it influence clinical outcome in patients, during a median follow-up of 6.3 (± 2.4) years. Patients produced stiffer fibrin clots (median [IQR] EM = 20.3 [14.9-28.1] vs. 12.8 [9.6-17.1] kdynes/cm²; p<0.0001) and displayed reduced response to fibrinolysis with lower fibrinolysis rate (6.7 [3.4-11.0] vs. 9.0 [5.0-16.7] sec-¹ x 10(-4); p<0.0001) than healthy controls. Carriage of factor XIII-A Leu34 led to a stepwise decrease in fibrinolysis rate with a significant gene-dose-effect in patients (7.7 [4.1-12.2] vs. 4.8 [3.0-8.5] vs. 4.3 [2.4-8.1] sec-¹ x 10(-4), for wild-type, heterozygous and homozygous, p for trend = 0.003) and a non-significant trend in controls (p = 0.01). In conclusion, FXIII-A Leu34 is a polymorphism which provides a strong resistance to fibrinolysis with a gene-dose effect, but does not relate to premature CAD or to recurrent coronary events in this study.

High doses of clopidogrel to overcome genetic resistance: the randomized crossover CLOVIS-2 (Clopidogrel and Response Variability Investigation Study 2).

OBJECTIVES: This study sought to determine whether the pharmacokinetic (PK) and pharmacodynamic (PD) responses to high or standard clopidogrel loading doses (LDs) differ according to CYP2C19*2 allele. BACKGROUND: CYP2C19 loss-of-function alleles are associated with reduced responsiveness to standard clopidogrel doses. METHODS: Young post-myocardial infarction patients heterozygous (wild type [wt]/*2, n = 43) or homozygous (*2/*2, n = 8) for the CYP2C19*2 genetic variant were matched with patients not carrying the variant (wt/wt, n = 58). All patients were randomized to a 300- or 900-mg clopidogrel LD. The relative reduction in residual platelet aggregation (RR-RPA, %) and the area under the plasma concentration time curve of active metabolite from baseline to 6 h after loading (AUC(0-6)) were compared according to both LD and CYP2C19*2 carriage. RESULTS: The 300-mg LD led to a gene-dose effect for RR-RPA (-65.7% ± 35.9% in wt/wt vs. -48.0% ± 38.4% in wt/*2 vs. -14.6% ± 32.4% in *2/*2; overall p value = 0.003, p = 0.03 for wt/wt versus wt/*2, p = 0.04 for wt/*2 versus *2/*2) with minor effect in *2/*2 carriers. After the 900-mg LD, the effect of the CYP2C19*2 variant on platelet inhibition was fully compensated in wt/*2 carriers but not in *2/*2 carriers (-83.6% ± 25.8% in wt/wt vs.-77.2% ± 26.9% in wt/*2 vs. -29.5% ± 26.8% in *2/*2; overall p value = 0.0003, p = 0.20 for wt/wt versus wt/*2, p < 0.001 for wt/*2 versus *2/*2). A similar pattern was observed for the active metabolite AUC(0-6) according to carriage of CYP2C19*2 for both LDs. There was a significant correlation between PK and PD responses irrespective of the LD. CONCLUSIONS: Carriers of CYP2C19*2 display significantly lower responses to clopidogrel with a gene-dose effect. Clopidogrel resistance can be overcome by increasing the dose in heterozygous carriers but not in homozygous carriers. (Clopidogrel and Response Variability Investigation Study 2 [CLOVIS-2]; NCT00822666).

Impact of red blood cell transfusion on platelet activation and aggregation in healthy volunteers: results of the TRANSFUSION study.

AIMS: The underlying mechanisms leading to recurrent ischaemic events or mortality after red blood cell (RBC) transfusion in anaemic acute coronary syndrome patients are poorly understood. The aim of this paper is to determine whether RBC transfusion increases platelet activation and aggregation. METHODS AND RESULTS: In vitro transfusions (n = 45) were performed by the addition of RBCs obtained from transfusion packs to fresh whole blood provided by healthy volunteers. Residual platelet aggregation (RPA) and maximal platelet aggregation (MPA) were assessed before and after in vitro transfusion using light transmission aggregometry performed with four different agonists. Flow cytometry was used for the measurement of P-selectin expression and vasodilatator-stimulated phosphoprotein (VASP) platelet reactivity index (PRI). To control for the effect of haemoconcentration, the same experiments were repeated after hematocrit adjustment using volunteer's platelet poor plasma. Transfusion increased platelet aggregation as measured by RPA with ADP 5 µM (57.7 ± 25 vs. 65.7 ± 24%; P = 0.03) or Collagen 2 µg/mL (59.4 ± 28 vs. 69.7 ± 24%; P = 0.03). There were no significant differences with Arachidonic Acid 1.25 mM or Epinephrine 20 µM and results were similar when MPA was considered. Platelet activation was also increased by transfusion as confirmed by an elevation of P-selectin expression induced by 20 µM ADP (12.2 ± 18 vs. 23.9 ± 18%; P = 0.002) or 50 µM ADP (15.4 ± 18.6 vs.26.8 ± 21.2%; P = 0.004) and an increase in VASP PRI (77.8 ± 6 vs. 81.9 ± 3%; P = 0.03). These effects were all independent of hematocrit. CONCLUSION: Red blood cell transfusion increases platelet activation and aggregation in vitro in healthy volunteers. This effect might be mediated through the P2Y(12) activation pathway.