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.

Risk Stratification in Arrhythmogenic Right Ventricular Cardiomyopathy/Dysplasia Without an Implantable Cardioverter-Defibrillator.

OBJECTIVES: The purpose of this study was to identify clinical factors associated with arrhythmic events and sudden cardiac death (SCD), and to evaluate the prognostic value of electrophysiological study (EPS) in arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) patients without implantable cardioverter-defibrillators (ICDs). BACKGROUND: ARVC/D is an inherited cardiomyopathy characterized by a risk of SCD. Few studies have evaluated predictive factors of ventricular arrhythmias (VAs) in patients without ICDs. METHODS: Between 2000 and 2010, all consecutive patients with ARVC/D without ICDs and with EPS at diagnosis were enrolled. Patients that received an ICD during follow-up were censored at the date of implantation, and in that case, only VAs that occurred before ICD implantation were analyzed. Risk factors for any VA event were determined by Cox regression. Patients that only experienced SCD or aborted cardiac arrest (ACA) were reported. RESULTS: A total of 137 consecutive patients (78% male) diagnosed with ARVC/D without ICD were enrolled. 31% had sustained ventricular tachycardia at diagnosis. After mean follow-up of 42 ± 31 months, 19 patients experienced an episode of sustained VA and 5 patients experienced a SCD/ACA. No event occurred in asymptomatic patients. Left ventricular ejection fraction ≤50% (p = 0.024), positive EPS (p = 0.017), and physical activity >6 h/week (p = 0.025) were independently associated with occurrence of VAs. SCD/ACA exclusively occurred in male probands with definite diagnosis and syncope. CONCLUSIONS: In this cohort of ARVC/D patients without ICD, left ventricular ejection fraction ≤50%, positive EPS, and physical activity >6 h/week were independent predictors of VAs, whereas asymptomatic patients at diagnosis were at low risk. EPS predicted all VAs but had limited value to predict SCD/ACA.

Implantable cardioverter-defibrillators in end-stage heart failure patients listed for heart transplantation: Results from a large retrospective registry.

BACKGROUND: Implantable cardioverter-defibrillators (ICDs) are recommended in patients with low ejection fraction. However, the survival benefit of ICDs in patients with end-stage heart failure listed for heart transplantation is unclear. AIM: To evaluate the ICD benefit on mortality in this population. METHODS: Three hundred and eighty consecutive patients listed for heart transplantation between 2005 and 2009 in one tertiary heart transplant centre were enrolled in a retrospective registry; 122 patients received an ICD before or within 3 months after being listed for heart transplantation (ICD group). Predictors of death on the waiting list were assessed by Cox regression. RESULTS: Overall, 15.6% of patients died while awaiting heart transplantation. Non-ICD patients presented more often haemodynamic compromise requiring mechanical circulatory support (29.1% vs. 9.8%; P<0.001), and were more likely to die while on the waiting list (19.0% vs. 8.3%; log-rank P=0.001). However, in the multivariable model, ICD did not remain an independent predictor of death. Need for mechanical circulatory support (P<0.001), low ejection fraction (P=0.001) and registration on the regular list (P=0.008) were the only independent predictors of death. Death was mainly caused by haemodynamic compromise (76.3% of deaths), which occurred more frequently in the non-ICD group (14.7% vs. 5.8%; log-rank P=0.002). Unknown/arrhythmic deaths did not differ significantly between the two groups (3.9% vs. 1.7%; log-rank P=0.21). ICD-related complications occurred in 21.4% of patients, mainly as a result of postoperative worsening of heart failure (11.9%). CONCLUSION: Haemodynamic failure appears as the main determinant of mortality in patients with end-stage heart failure awaiting heart transplantation. ICD seems to have little benefit on survival in this population.

Impact of non-steroidal anti-inflammatory drugs (NSAIDs) on cardiovascular outcomes in patients with stable atherothrombosis or multiple risk factors.

BACKGROUND: We aimed to assess whether the use of non-steroidal anti-inflammatory drugs (NSAIDs) is associated with an increased risk of cardiovascular (CV) events in stable patients with established atherothrombosis or multiple risk factors. METHODS: We analysed the 23,728 European patients of the REACH Registry; 20,588 (86.8%) had established atherothrombotic disease and 3140 (13.2%) had multiple risk factors only. Aspirin (ASA) and/or NSAIDs use was determined at enrolment and ischemic events were recorded over two years of follow-up. cMACCE was defined as the composite of CV death, MI or stroke. Bleeding was defined as any bleeding leading to both hospitalisation and transfusion. RESULTS: The mean age of population was 67.2±9.8years. At baseline, 1573 patients (6.6%) received NSAIDs and 15,395 (64.9%) received ASA. Four groups were defined: 1) no ASA/no NSAIDs, 2) ASA only, 3) NSAIDs only, 4) NSAIDs+ASA, with 7722 (32.5%), 14,433 (60.8%), 611 (2.6%) and 962 (4.1%) patients in these groups, respectively. Among the 22,028 (92.8%) with complete 2-year follow-up, 683 (3.2%) died from CV causes, while 395 (1.9%) had MI, 665 (3.1%) stroke, 1651 (7.6%) cMACCE and 199 (1.0%) bleeding. After adjustment, NSAID use was independently associated with an increased risk of stroke (OR 1.635; 95% CI 1.239-2.159, p<0.001), and a trend towards an increased bleeding rate (OR 1.554; CI 95% 0.960-2.51, p=0.07). No association was found between NSAID use and MI or MACCE. CONCLUSIONS: In stable atherothrombosis patients, the use of NSAIDs appears to be independently associated with an increased cerebrovascular event risk.

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).