Absorption and efficacy of acetylsalicylic acid in patients with short bowel syndrome.

BACKGROUND: The patients with a short bowel (SB) frequently require antiplatelet therapy. Resection of the bowel is likely to modify the absorption and first-pass effect of drugs. No data on the absorption and efficacy of the cardiovascular dose of aspirin (75-160 mg) in these patients have been published. OBJECTIVE: To evaluate the efficacy of a low dose of aspirin in patients with SB caused by mesenteric ischemia. METHODS: The efficacy of a low dose of aspirin was assessed in 10 consecutive SB patients, both 1 hour and 24 hours after administration (peak and trough value, respectively). The primary criterion was the inhibition of platelet aggregation, as assessed by light transmission aggregometry, triggered with 0.5 mg/mL arachidonic acid. Biological efficacy of aspirin was also evaluated by serum thromboxane B2 value and by platelet function analyzer-100. RESULTS: At its peak value, aspirin had the expected efficacy, as demonstrated both by light transmission aggregometry and the other methods. However, 24 hours after administration, as many as 30% of patients had lost the pharmacological efficacy of their aspirin. CONCLUSION: We show for the first time that with at least 30 cm of small intestine, all patients with SB absorb sufficient oral aspirin in a cardiovascular dose to rapidly exert the expected level of antiplatelet activity. But given only once daily, aspirin does not provide stable 24-hour antiplatelet protection in 30% of patients, because of increased platelet turnover, as usually observed in patients with extensive vascular pathology, diabetes, or inflammation.

Monitoring persistent platelet reactivity in patients with unprotected left main stenting.

OBJECTIVE: This study sought to determine the rate and potential clinical impact of persistent platelet reactivity (PPR) in unprotected left main (ULMD) stenting. BACKGROUND: PPR under aspirin or thienopyridines is associated with acute events after angioplasty. METHODS: We prospectively included 125 patients referred for ULMD stenting. For the first 64 patients (ALMA-1), angioplasty was performed under aspirin and clopidogrel without platelet reactivity assessment. For the last 61 patients (ALMA-2), platelet reactivity was assessed before angioplasty: in patients with aspirin-related PPR, aspirin twice daily was given and in those with clopidogrel-related PPR, clopidogrel double dose or prasugrel was used. RESULTS: Overall, patients' mean age was 69 ± 13 years, 37% were diabetic, and 37% had non-ST segment elevation myocardial infarction (NSTEMI). Patients' characteristics were similar in both studies with isolated left main in 14% and associated with 1-, 2-, or 3-vessel disease in 23%, 36%, and 27%, respectively. Mean SYNTAX score was 23 ± 9. Procedural characteristics were similar using provisional T stenting in 69%, T stenting in 27%, and other techniques in 4%. In ALMA-2, 28% patients had PPR for aspirin, 29% for clopidogrel, and 8% for both. Aspirin twice daily was given in 28% of patients, clopidogrel double dose in 26%, and prasugrel in 31%. The rate of 1-year major adverse cardiovascular and cerebrovascular events (MACCE) was lower in ALMA-2 versus ALMA-1 (8.2% vs. 20.8%; P = 0.04) as a composite end-point of cardiovascular death or stent thrombosis (0.0% vs. 8.3%; P = 0.02). CONCLUSION: PPR under aspirin and thienopyridines is frequent in ULMD stenting and could be related to subsequent major events.

Deep phenotyping and biomarkers of various dairy fat intakes in an 8-week randomized clinical trial and 2-year swine study.

Health effects of dairy fats (DF) are difficult to evaluate, as DF intakes are hard to assess epidemiologically and DF have heterogeneous compositions that influence biological responses. We set out to find biomarkers of DF intake and assess biological response to a summer DF diet (R2), a winter DF diet (R3), and a R3 supplemented with calcium (R4) compared to a plant-fat-based diet (R1) in a randomized clinical trial (n=173) and a 2-year study in mildly metabolically disturbed downsized pigs (n=32). Conventional clinical measures were completed by LC/MS plasma metabolomics/lipidomics. The measured effects were modeled as biological functions to facilitate interpretation. DF intakes in pigs specifically induced a U-shaped metabolic trajectory, reprogramming metabolism to close to its initial status after a one-year turnaround. Twelve lipid species repeatably predicted DF intakes in both pigs and humans (6.6% errors). More broadly, in pigs, quality of DF modulated the time-related biological response (R2: 30 regulated functions, primarily at 6 months; R3: 26 regulated functions, mostly at 6-12 months; R4: 43 regulated functions, mostly at 18 months). Despite this heterogeneity, 9 functions overlapped under all 3 DF diets in both studies, related to a restricted area of amino acids metabolism, cofactors, nucleotides and xenobiotic pathways and the microbiota. In conclusion, over the long-term, DF reprograms metabolism to close to its initial biological status in metabolically-disrupted pigs. Quality of the DF modulates its metabolic influence, although some effects were common to all DF. A resilient signature of DF consumption found in pigs was validated in humans.

Biological efficacy of twice daily aspirin in type 2 diabetic patients with coronary artery disease.

BACKGROUND: Diabetes is associated with a high rate of events after acute coronary syndrome and percutaneous coronary intervention despite aspirin treatment. Once daily aspirin might not provide 24-hour stable biological efficacy in patients with diabetes. We compared the biological efficacy of the same daily dose of aspirin given either once (OPD) or divided twice per day in a population of diabetic patients with previous coronary artery disease. METHODS: Ninety-two consecutive diabetic patients with at least 1 criteria of time-dependent aspirin efficacy, elevated high-sensibility C-reactive protein (hs-CRP), fibrinogen, platelet count, or active smoking were prospectively included. Consecutive patients were randomly treated with 150-mg aspirin daily given either OPD (150 mg in the morning) or twice per day (75 mg in the morning and 75 mg in the evening) in a crossover study. The main outcome was platelet reactivity to arachidonic acid (0.5 mg/mL) measured by light transmission aggregometry at trough level before morning aspirin intake. RESULTS: Mean maximum aggregation intensity triggered by arachidonic acid was 19.7% ± 15.4% on OPD and 11.9% ± 10.4% on twice per day (P < .0001). Biological resistance (maximum aggregation intensity ≥20%) was observed in 42% of patients on OPD and 17% on twice per day (P < .001). Of the 39 patients with biological resistance on OPD, 24 (62%) overcame resistance on twice per day. Of the 16 resistant on twice per day, only 1 patient (6%) overcame resistance on OPD. Results were concordant with global evaluation of platelet reactivity by Platelet Function Analyzer-100. A better twice per day efficacy was independent of clopidogrel cotreatment. CONCLUSION: In a population of diabetic patients with coronary artery disease and a high risk of time-dependent aspirin resistance, aspirin divided twice per day can significantly decrease the rate of biological loss of efficacy at trough level.

Amoxicillin/clavulanic acid-warfarin drug interaction: a randomized controlled trial.

AIMS: To investigate whether an interaction exists between amoxicillin/clavulanic acid (amoxiclav) and warfarin in patients treated with stable oral anticoagulant therapy. METHODS: In a double-blind, cross-over, placebo-controlled study, 12 patients on stable warfarin therapy, received a 7 day amoxiclav regimen or placebo. RESULTS: The mean maximum increase in INR observed was 0.22 ± 0.3 with amoxiclav vs. 0.24 ± 0.6 with placebo (P=0.94). The day 7-day 1 factor II, R(-) and S(-) warfarin plasma concentrations were similar during the amoxiclav and placebo study periods (P=0.81, P=0.45, P=0.75, respectively). CONCLUSION: Amoxiclav did not modify anticoagulation in patients treated with stable warfarin therapy and without infection.

Interaction between acetaminophen and warfarin in adults receiving long-term oral anticoagulants: a randomized controlled trial.

PURPOSE: We investigated whether acetaminophen, given at 2 g/day and 3 g/day might potentiate the anticoagulant effect of warfarin. METHODS: Forty-five patients on stable warfarin therapy, enrolled in this prospective, randomized, parallel (three arms), placebo-controlled study, received a 10-day regimen of acetaminophen (2 g/day or 3 g/day) or placebo. RESULTS: The mean maximal INR increase was 0.70 ± 0.49 and 0.67 ± 0.62 in patients receiving acetaminophen at 2 g/day and 3 g/day, respectively (P=0.01 for the respective comparisons versus placebo). The INR increase became significant on day 3 and was independently and significantly predicted by a maximal decrease in factor II (R(2)=0.36, P<0.0001), factor VII (R (2)=0.46, P<0.0001) and a maximal increase in acetaminophen plasma concentrations (R(2)=0.563, P<0.0001). CONCLUSION: Acetaminophen, at 2 g/day or 3 g/day, enhanced the anticoagulant effect of warfarin in stable patients, thus requiring close INR monitoring in the clinical setting.

Is platelet function testing at the acute phase under P2Y12 inhibitors helpful in predicting bleeding in real-life patients with acute coronary syndrome? The AVALANCHE study.

BACKGROUND: In patients with acute coronary syndrome (ACS), current international guidelines recommend newer potent and predictable P2Y12 inhibitors as first-line treatment despite a greater bleeding risk compared with clopidogrel. AIM: To determine if platelet function testing can predict bleeding in real-life patients with ACS treated with newer P2Y12 inhibitors. METHODS: In this retrospective study, all consecutive adults admitted to the Lariboisière University Hospital for ACS, whatever the P2Y12 inhibitor prescribed, who had platelet function testing (vasodilator-stimulated phosphoprotein phosphorylation [VASP] index and aggregation tests) during the initial hospital stay were included. Follow-up was performed to record bleeding events according to the Bleeding Academic Research Consortium (BARC) classification. RESULTS: A total of 364 patients were included, treated with ticagrelor (n=123), prasugrel (n=105) or clopidogrel (n=136); 42.3% after an ST-segment elevation myocardial infarction, 27.1% after a non-ST-segment elevation myocardial infarction and 30.6% with unstable angina. Mean age was 64±11 years. Median VASP index was significantly lower with the newer P2Y12 inhibitors (14% under ticagrelor, 14% under prasugrel) than with clopidogrel (42%). Despite these differences in the degree of platelet inhibition, the occurrence of bleeding (BARC 2-5) during follow-up was 7.7% overall, and was similar for all P2Y12 inhibitors (ticagrelor 8.9%; prasugrel 6.6%; clopidogrel 7.4%). For each P2Y12 inhibitor, it was impossible to determine a VASP index threshold under which bleeding was significantly greater during follow-up. Similarly, ADP-induced aggregation was more profoundly inhibited by ticagrelor and prasugrel than by clopidogrel, but this did not allow a threshold to be set for increased haemorrhagic risk. CONCLUSIONS: Despite the substantial occurrence of bleeding in patients with ACS during follow-up, neither the VASP index nor platelet aggregation test results measured at the acute phase were helpful in predicting bleeding risk. Whether platelet function testing could be helpful later in the course of treatment remains to be evaluated.

Effect of milk fat on LDL cholesterol and other cardiovascular risk markers in healthy humans: the INNOVALAIT project.

BACKGROUND: Milk has a specific saturated fatty acid profile and its calcium content may change the kinetics of fat absorption. OBJECTIVE: The goal of this study was to compare the effect on LDL Cholesterol and other risk markers of four isolipidic diets differing by their fat food source, vegetable fat, spring milk fat, winter milk fat or winter milk fat supplemented with calcium, in healthy moderately hypercholesterolemic humans. INDIVIDUALS AND METHODS: This double-blind, randomized trial with four parallel arms included 172 healthy adults with plasma LDL cholesterol (LDL-C) from 130 to 220 mg/dL and triglycerides below 300 mg/dL. Individual meal plans ensured a stable energy intake. In the three diets containing milk fat, milk fat provided 38% of energy. Vegetable fat and spring milk fat diets provided the same amount of saturated fatty acids while the winter milk fat diets were slightly richer in saturated fatty acids. Vegetable fat diet and winter milk fat diets provided the same amount of palmitic acid (7.0% EI), while the spring milk fat diet was slightly poorer in this fatty acid (5.1% EI). Cardiovascular risk markers were analyzed after 8 weeks of dietary intervention. RESULTS: There was no significant difference in LDL-C and other markers, except total cholesterol (TC), apo C3 and CRP. TC was significantly higher with spring milk fat than with vegetable fat. CONCLUSIONS: In this trial, the chosen vegetable fat did not have a significant beneficial effect on LDL-C compared to dairy fat. However, sub-group analysis showed differences in TC, apo C3 and CRP. These results need confirmation and long-term studies aiming at cardiovascular endpoints are warranted.

Adding intravenous unfractionated heparin to standard enoxaparin causes excessive anticoagulation not detected by activated clotting time: results of the STACK-on to ENOXaparin (STACKENOX) study.

BACKGROUND: The STACKENOX study assessed the cumulative anticoagulation effect of administering stack-on intravenous unfractionated heparin (UFH) to subjects already receiving enoxaparin. METHODS: Seventy-two healthy subjects aged 40 to 60 years received subcutaneous enoxaparin (1 mg/kg every 12 hours) for 2.5 days (steady state) and were randomized to receive a 70 IU/kg intravenous UFH bolus 4, 6, or 10 hours after the final enoxaparin dose. Anticoagulation levels were assessed in subjects receiving enoxaparin alone and after the UFH bolus by monitoring activated clotting time (ACT), anti-Xa and anti-IIa activities, and thrombin generation (endogenous thrombin potential [ETP]). RESULTS: After the final enoxaparin dose, ETP levels decreased by 40%; anti-Xa and anti-IIa activities increased, as expected; and ACT levels did not indicate any anticoagulation effect. Stack-on UFH at 4, 6, or 10 hours after the last enoxaparin dose significantly increased anti-Xa and anti-IIa activities (P < .0001) to well above accepted therapeutic levels and resulted in total inhibition of thrombin generation for > or =2 hours; ACT levels remained within the range commonly observed in subjects receiving UFH. CONCLUSIONS: The administration of stack-on UFH to subjects already receiving recommended enoxaparin dosing may result in over-anticoagulation, and should be avoided. Activated clotting time assessment did not detect the over-anticoagulation resulting from co-administration of enoxaparin and UFH.

Functional variability of platelet response to clopidogrel correlates with P2Y(12) receptor occupancy.

Interindividual variability of response to clopidogrel is currently a subject of much interest. We tested the hypothesis that functional variability in the platelet response to clopidogrel correlates with occupancy of the platelet P2Y(12) receptor by clopidogrel active metabolite. Healthy subjects were screened after seven days' treatment with clopidogrel 75 mg/day to select three clopidogrel-response groups (n = 12/group), defined as 'average' (40-60% inhibition of platelet aggregation [IPA]), 'low' (<10% IPA) or 'high' (>80% IPA) responders. After a two- to six-week wash-out period, subjects were randomized (double-blind) to clopidogrel 75 mg/day (n = 10/group) for 10 days, followed by clopidogrel 300 mg on day 11, or placebo (n = 2/group). IPA induced by adenosine diphosphate (ADP), and P2Y(12) receptor occupancy were measured repeatedly. The incidence of low responders was 3.7%, and low responses to clopidogrel were maintained during the randomized evaluation phase. Treatment with clopidogrel for 10 days induced a significant increase in P2Y(12) receptor occupancy in each group of responders versus placebo; receptor affinity was unchanged. This reduction correlated with IPA response (r = 0.54). The additional 300 mg dose of clopidogrel on top of 75 mg chronic treatment increased IPA and P2Y(12) receptor occupancy in all groups, but relatively more in low responders. Variability in the response to clopidogrel appears to be linked to differences in P2Y(12) receptor occupancy. An additional 300 mg dose of clopidogrel improves both IPA and P2Y(12) receptor occupancy mostly in the subset of 'low' responders.

A novel experimental thrombotic myocardial infarction and primary angioplasty model in swine.

AIMS: We sought to develop a reproducible animal model for acute myocardial infarction (AMI) in adult atherosclerosis-prone pigs. METHODS AND RESULTS: A coil was placed in the right coronary artery or the left anterior descending artery in 26 downsized spontaneously hypercholesterolaemic pigs and left untreated until thrombotic occlusion. Then, we crossed the thrombotic occlusion with a guidewire, followed by predilatation, thrombus visualisation with optical coherence tomography (OCT) imaging and, finally, deployment of a stent and repeated OCT. After revascularisation, we calculated the index of microcirculatory resistance (IMR). After a feasibility phase (six animals), acute thrombotic occlusion was achieved in all 20 pigs. Eighteen animals were successfully revascularised and survived until sacrifice. Thrombus formation was confirmed by OCT, measurement of thrombin-antithrombin complexes and pathology examination. Myocardial necrosis was confirmed by troponin T elevation, myocardial staining and pathology examination. Distal thrombotic embolisation and microvascular obstruction were supported by increased IMR and pathology examination. CONCLUSIONS: A porcine model of thrombotic occlusion AMI in miniaturised adult spontaneously atherosclerosis-prone pigs is feasible by percutaneous intracoronary placement of a coil. The reperfusion by angioplasty completed this model which mirrors human pathological conditions with myocardial infarction, necrosis and distal embolisation.

Tinzaparin and enoxaparin given at prophylactic dose for eight days in medical elderly patients with impaired renal function: a comparative pharmacokinetic study.

Low-molecular-weight heparins (LMWHs) accumulate in patients with impaired renal function. As this accumulation depends on heparin chain length and subsequent reticulo-endothelial/renal elimination, LMWHs might have different pharmacodynamic profiles. The primary objective was to examine if any accumulation effect of two LMWHs, enoxaparin and tinzaparin, occurred after repeated administration of a prophylactic dose over eight days in elderly patients (age >75 years) with creatinine clearance between 20 and 50 ml/min and body weight <65Kg. Patients were openly randomized to two groups (enoxaparin 4,000 IU or tinzaparin 4,500 IU once daily). Anti-Xa was measured on day 1 and day 8. Blood samples were taken at 0, 2, 4, 5, 6, 9, 12, 16 and 24 hours. The primary end point was the accumulation factor calculated as a ratio between the maximal anti-Xa activity on day 1and day 8. Fifty-five patients were included (mean age 87.9 +/- 5.5). The creatinine clearance was 34.7 +/- 11.4 ml/min; the body weight was 52.3 +/- 8.6 kg. The accumulation factor defined was not significant for tinzaparin (1.05, p = 0.29) while it was significantly enhanced for enoxaparin (1.22, p < 0.0001). In this pharmacodynamic study performed in elderly patients with impaired renal function, a statistically significant accumulation effect was observed after eight days of prophylactic treatment with enoxaparin but not with tinzaparin, which are two LMWHs with different chain lengths. Trials based on clinical end points should be conducted to evaluate the clinical relevance of these observations.

Bivalirudin infusion to reduce ventricular infarction: the open-label, randomised Bivalirudin Infusion for Ventricular InfArction Limitation (BIVAL) study.

AIMS: The aim of the study was to investigate whether bivalirudin versus unfractionated heparin (UFH) reduces infarct size (IS) for primary percutaneous coronary intervention (PPCI) in large acute myocardial infarction (AMI). METHODS AND RESULTS: This multicentre open-label trial randomised 78 patients undergoing PPCI for large AMI to bivalirudin or UFH. The primary endpoint was IS, assessed by cardiac magnetic resonance (CMR) five days after PPCI. Secondary endpoints included index of microcirculatory resistance (IMR), CMR-assessed microvascular obstruction (MVO) and ejection fraction, and biomarkers for thrombin activity and cell injury. No difference was observed in mean IS at five days (25.0±19.7 g for bivalirudin vs. 27.1±20.7 g for UFH; p=0.75). Early MVO was numerically lower with bivalirudin (5.3±5.8 g vs. 7.7±6.3 g; p=0.17), with no significant difference in ejection fraction at 90 days (54.6±12.0% vs. 49.1±12.1%; p=0.11). In the biomarkers, thrombin-antithrombin complexes were reduced by 4.8 ug/L over the first day for bivalirudin versus an increase of 1.9 ug/L in the heparin arm (p=0.0003). Acute IMR was lower (43.5±21.6 vs. 68.7±35.8 mmHg×s, respectively; p=0.014). In a planned interim analysis, an approximate 11% reduction in IS was observed with bivalirudin; the trial was discontinued for futility. CONCLUSIONS: This study did not achieve its primary endpoint of significant infarct size reduction in PPCI by prolonged bivalirudin infusion compared to UFH, even though complete thrombin inhibition was achieved in the acute phase, with a lower myocardial microcirculation resistance at the end of the procedure.

Interaction between paracetamol and warfarin in patients: a double-blind, placebo-controlled, randomized study.

BACKGROUND AND OBJECTIVES: Paracetamol (acetaminophen) has occasionally been reported to interact with warfarin. The primary end-point of this study was to investigate whether paracetamol initiation potentiates the anticoagulant effect of warfarin and the mechanism of the interaction. DESIGN AND METHODS: In a double-blind placebo-controlled, randomized, cross-over study, 20 patients on stable oral anticoagulant therapy with warfarin for at least 1 month were randomized to receive placebo or paracetamol 1g four times daily for 14 days. International Normalized Ratio (INR) and clotting factors activities were measured before the first administration and then on days 2, 4, 7, 9, 11,14. RESULTS: Mean INR rose rapidly after the start of paracetamol and was significantly increased within one week of paracetamol intake compared to placebo, p=0.0002. The INR values reached a mean maximum of 3.45+/-0.78 with paracetamol versus 2.66+/-0.73 with placebo (p=0.03), corresponding to a maximum increase from baseline of 1.20+/-0.62 with paracetamol versus 0.37+/-0.48 with placebo (p<0.001). Together with the rise in INR on paracetamol treatment there were significant reductions in the vitamin K-dependent clotting factors II, VII, IX and X. INTERPRETATION AND CONCLUSIONS: The most plausible hypothesis to explain the in vivo interaction is that paracetamol (or its metabolites) interfere with enzymes involved in vitamin K-dependent coagulation factor synthesis. Paracetamol at 4 g daily (a dose higher than that used in clinical practice) potentiates the anticoagulant response produced by warfarin. Clinicians should be aware of this clinically significant and underestimated interaction.

Relationship of circulating biomarkers of inflammation and hemostasis with preclinical atherosclerotic burden in nonsmoking hypercholesterolemic men.

BACKGROUND: Relations of mediators of inflammation and hemostasis with preclinical atherosclerosis have been poorly analyzed. The aim of this study was to test potential associations of these blood markers with indicators of cardiovascular risk and atherosclerotic burden in asymptomatic, nonsmoking, hypercholesterolemic men. METHODS: A total of 87 men underwent cardiovascular risk assessment by means of 10-year Framingham risk calculation (median 9%) and atherosclerotic burden evaluation by means of ultrasonographic measurement of common carotid intima-media thickness and assessment of atherosclerotic plaques at three arterial sites (three-site plaques). RESULTS: Of the markers C-reactive protein, tumor necrosis factor-alpha, interleukin-10, factor VIIc, fibrinogen, plasminogen activator inhibitor-activator, soluble intercellular adhesion molecule-1, soluble P-selectin (sP-selectin), and von Willebrand factor, only sP-selectin was positively and independently associated with high Framingham risk score (>9%) (71.7 +/- 3.6 ng/mL, n = 33 v 59.6 +/- 2.8, n = 54; mean +/- SEM; P < .05) and with three-site plaques (75.4 +/- 5.7 ng/mL, n = 14 v 62.0 +/- 2.5, n = 73; P < .05). After adjustment for all of the above markers and for cardiovascular risk factors, odd ratios of having high Framingham risk and three-site plaques were 3.38 (1.43 to 10.21) and 5.23 (1.74 to 23.52) respectively, per 1-standard deviation increase in sP-selectin. CONCLUSIONS: These results confirm that among several hemostasis and inflammation mediators, only sP-selectin blood level was associated with preclinical atherosclerosis. It might confer to sP-selectin measurement a clinical usefulness for detecting and managing high cardiovascular risk in primary prevention.

[Use and monitoring of vitamin K antagonists in everyday medical practice. French results of the international ISAM study of patients with nonvalvular atrial fibrillation]. / Utilisation et suivi biologique des antivitamines K en pratique médicale courante. Résultats français de l'étude internationale ISAM chez des patients ayant une fibrillation auriculaire.

INTRODUCTION: Bleeding complications of vitamin K antagonist (VKA) therapy are currently the most frequent iatrogenic event in France. OBJECTIVES: The aim of the ISAM study, an international longitudinal observational survey was to evaluate the use of VKA treatment and the quality of laboratory monitoring in everyday medical practice. METHODS: In France, a representative sample of general practitioners and cardiologists selected patients with nonvalvular atrial fibrillation who had been treated with VKA for at least 60 days during the past 12 months. Physicians and patients responded to standardized questionnaires collecting retrospective data for the previous year. RESULTS: Overall, 43 general practitioners and 20 cardiologists recruited 278 patients who completed questionnaires. INR was at least 2 for 264 patients during the study period. During the year preceding inclusion, INR had been within the target range (i.e., between 2.0 and 3.0) 59% of the time and above 3.0 27%. Physicians reported having giving approximately half their patients written recommendations about the VKA dosage regimen, but only 3% supplied a specific VKA information and monitoring booklet. Most patients (65%) reported receiving information on VKA therapy from their general practitioners, although 18% said they had not been informed about their treatment, 44% did not know their target INR, and 66% were unaware that bleeding events were a matter of concern. Finally, 45% of patients reported carrying a card indicating that they were taking VKA. CONCLUSION: Overall, these results show that better education of both physicians and patients could help to improve management, appropriate use and laboratory monitoring of VKA treatment.

Enoxaparin chains stored during chronic treatment are mobilized by a bolus of unfractionated heparin: insights from the STACKENOX study.

The initial STACKENOX (STACK-on to ENOXaparin) study investigated the effect of stacking unfractionated heparin (UFH) onto a chronic treatment with enoxaparin, a common practice in interventional cardiology when a patient treated with enoxaparin receives an additional bolus of UFH at the time of percutaneous coronary intervention. The study brought to light some unexpected consequences on coagulation tests and hemorrhagic risk. This substudy was performed to provide a pharmacological explanation for these observations. Seventy-two healthy individuals previously treated with enoxaparin for 2.5 days received a stack-on of 70 IU/kg intravenous UFH dose 4, 6, or 10 h after the last enoxaparin dose. Anticoagulation activity was monitored by activated partial thromboplastin time, anti-Xa and anti-IIa activities and a thrombin generation test. In parallel, plasma samples of the individuals receiving the chronic enoxaparin treatment obtained at 4, 6, or 10 h after the last enoxaparin dose were spiked in vitro with a dose of UFH reproducing the concentration achieved in vivo after the bolus of UFH alone. In-vivo stack-on of UFH induced an over-anticoagulation identified by changes in anti-Xa and, less markedly, in anti-IIa and activated partial thromboplastin time levels, whereas in-vitro UFH spiking, only produced an additive effect. We hypothesize that the potentiation of UFH on anti-Xa activity observed in vivo may caused by the UFH bolus mobilizing enoxaparin chains stored in the endothelial glycocalyx during chronic pretreatment. This over-anticoagulation and its potential hemorrhagic risk after stack-on of UFH have obvious clinical implications.

Measuring non-vitamin K antagonist oral anticoagulant levels: When is it appropriate and which methods should be used?

BACKGROUND: Although the need for an emergency intervention may merit laboratory measurement of non-vitamin K antagonist oral anticoagulant (NOAC) concentration or anticoagulant activity, NOACs are not supposed to require routine monitoring due to their stable pharmacological profiles compared with warfarin. AIMS: To examine situations where NOAC measurement may be useful and to provide information about methodologies available to measure NOAC-related anticoagulation activity. SUMMARY OF REVIEW: The routine coagulation tests, including prothrombin time, thrombin time, activated partial thromboplastin time, and international normalized ratio, have variable sensitivities to NOACs. Tests have been developed for use with specific NOACs, e.g. diluted thrombin time or chromogenic factor Xa assays. In emergency situations, such as severe bleeding, stroke, or a requirement for urgent surgery or procedures, there may be a need to assess anticoagulant activity to guide clinical decision making. In cases where neutralization of the anticoagulant effect is warranted, specific reversal agents are likely to become invaluable medical tools. Evidence to date suggests that dosing decisions for NOACs based on clinical features (e.g. age or renal function) can help optimize the benefit-risk balance without assessment of anticoagulant activity in non-emergency routine situations. CONCLUSIONS: Regular monitoring of NOAC levels does not provide benefits and cannot be recommended at present. In some specific circumstances, e.g. severe bleeding, before urgent surgery, or before thrombolysis, measurement may be beneficial to assess whether a patient is actively anticoagulated. The availability of NOAC-specific reversal agents may change management practices in emergencies.