Interaction between warfarin and short-term intravenous amiodarone in intensive care unit patients after cardiac surgery

Background

Amiodarone and warfarin are sometimes administered immediately after cardiac surgery. Although the interaction between long-term oral amiodarone and warfarin has been reported, the interaction between warfarin and short-term intravenous amiodarone has not been reported. In this study, we investigated the effect of short-term intravenous amiodarone on the anticoagulant effect of warfarin in patients who underwent cardiac surgery.

Methods

We retrospectively reviewed the medical records of 11 patients who received oral warfarin before and after cardiac surgery, and loading doses of 125–150 mg or a 750 mg continuous infusion of amiodarone, or both in the intensive care unit (ICU) within 5 days after the surgery between July 2011 and January 2017. The prothrombin time-international normalized ratio (PT-INR)/daily warfarin dose (PT-INR/dose) was used as an indicator of anticoagulant effect. The values before surgery were considered as the baseline.

Results

The PT-INR and PT-INR/dose values were elevated in 7 and 10 patients, respectively, after amiodarone administration. The mean PT-INR values were not significantly different before and after amiodarone administration (2.13 ± 0.58 vs 2.29 ± 0.50, respectively, p = 0.643). In contrast, the mean PT-INR/dose values were significantly elevated after the administration of amiodarone (0.93 ± 0.46 vs 1.54 ± 0.63, respectively, p = 0.002).

Conclusions

Short-term intravenous amiodarone enhanced the anticoagulant effect of warfarin in patients admitted to the ICU after cardiac surgery. We suggest that the dose of warfarin should be carefully adjusted for a few days after cardiac surgery if intravenous amiodarone is coadministered.

An analysis on distribution and inter-relationships of biomarkers under rivaroxaban in Japanese patients with non-valvular atrial fibrillation (CVI ARO 1)

Prothrombin time (PT) has been widely used for measuring anticoagulation intensity under rivaroxaban therapy, but precise information has not been well established yet. Consecutive 96 non-valvular atrial fibrillation (NVAF) under rivaroxaban between Jan/June, 2015 were recruited. Serum concentration (SC) and PT with 5 representative reagents available in Japan (Neoplastin Plus®, Thromborel S®, Thrombocheck PT®, Thrombocheck PT Plus®, and Recombiplastin®) at 2-4 hours after (peak) and before intake of rivaroxaban (trough) were measured at outpatient clinic in the cardiovascular institute (CVI ARO study 1). Nonlinear mixed-effects modelling was used to model the population pharmacokinetics and pharmacodynamics of rivaroxaban. An oral one-compartment model was employed to describe the population pharmacokinetics of rivaroxaban. The pharmacokinetics of rivaroxaban were affected by creatinine clearance, alanine aminotransferase, and use of CYP3A4 or P-gp inhibitors. PTs with 5 reagents were predicted by pharmacodinamic models with SC, hematocrit, serum albumin, and age, with medium predicting ability (highest/lowest R2 = 0.746/0.658 in Recombiplastin/Thromborel S, respectively). This population analysis in NVAF patients under rivaroxaban therapy demonstrated that pharmacokinetics of rivaroxaban was described by an oral one-compartment model with expected covariates, and can be assessed by PT with available reagents in Japan with medium predicting ability.

The clinical impact of edoxaban for the patients with postoperative anemia after total hip arthroplasty

BACKGROUND

Postoperative anemia is a common complication after total hip arthroplasty (THA). However, the effect of edoxaban on postoperative anemia after THA remains unclear. Here, we retrospectively evaluated the clinical assessment of postoperative anemia and the associated changes of coagulation parameters in patients undergoing thromboprophylaxis with edoxaban compared with fondaparinux as a conventional anticoagulant thromboprophylactic agent after THA.

METHODS

One hundred and forty-nine patients who underwent THA from July 2010 to June 2012 were divided into two groups, according to whether they were operated on before or after the approval of edoxaban: the fondaparinux group (Group F: 86 patients) and the edoxaban group (Group E: 63 patients). The frequency of postoperative anemia and blood coagulation values were investigated.

RESULTS

Postoperative anemia developed more frequently in Group E than in Group F after surgery. However, the degree of postoperative anemia showed no significant difference between the groups. Meanwhile, prothrombin time (PT), prothrombin time-international normalized ratio (PT-INR), and activated partial thromboplastin time were markedly higher in patients with edoxaban-associated postoperative anemia, which showed an increased potential to predict the occurrence of postoperative anemia. Additionally, both PT and PT-INR in Group E were also correlated with the volume of estimated blood loss.

CONCLUSION

The frequency of postoperative anemia was increased in patients treated with edoxaban, compared to fondaparinux, after THA. Edoxaban thromboprophylaxis might, therefore, require more careful monitoring to prevent postoperative anemia. Additionally, particular prolongation of PT and PT-INR induced by edoxaban treatment might predict postoperative anemia.

Effect of Centrifuge Temperature on Routine Coagulation Tests

BACKGROUND

This study investigated the effects of cooled and standard centrifuges on the results of coagulation tests to examine the effects of centrifugation temperature.

METHODS

Equal-volume blood samples from each patient were collected at the same time intervals and subjected to standard (25°C) and cooled centrifugation (2-4°C). Subsequently, the prothrombin time (PT), international normalized ratio (INR), activated partial thromboplastin time (aPTT), fibrinogen, and D-dimer values were determined in runs with the same lot numbers in the same coagulation device using the Dia-PT R (PT and INR), Dia-PTT-liquid (aPTT), Dia-FIB (fibrinogen), and Dia-D-dimer kits, respectively.

RESULTS

The study enrolled 771 participants. The PT was significantly (p < 0.018) higher in participants on anticoagulant therapy. The respective median values of the test parameters determined using the standard and cooled centrifuges were as follows: PT 10.30 versus 10.50 s; PT (INR) 1.04 versus 1.09 s; APTT 28.90 versus 29.40 s; fibrinogen 321.5 versus 322.1 mg/dL; and D-dimer 179.5 versus 168.7 µg FEU/mL. There were significant differences (p < 0.001) in the parameters between the values obtained with the standard and cooled centrifuges.

CONCLUSIONS

Centrifuge temperature can have a significant effect on the results of coagulation tests. However, broad and specific disease-based studies are needed.

Coronary Artery Disease Presentation and Its Association with Shortened Activated Partial Thromboplastin Time

Background: Standard coagulation screening tests are important constituents of basic examinations in clinical laboratories. There is no clear evidence of a relation between the type of clinical presentation and coagulation parameters in patients with suspected coronary artery disease. Methods: This cross-sectional study included 539 patients who underwent coronary angiography in Tehran Heart Center between November 2012 and January 2013. Patients presented with ST-segment-elevation myocardial infarction (STEMI), non-STEMI, unstable angina, or stable angina. Prothrombin time (PT), international normalized ratio (INR), and activated partial thromboplastin time (APTT) were measured before angiography and compared between the clinical presentation groups. Results: The mean age of the patients was 59.156 ± 11.05 years, and 47.7% were male. STEMI was reported in 41(7.6%) patients, non-STEMI in 42 (7.8%), unstable angina in 304 (56.4%), and stable angina in 152 (28.2%). No difference in the mean PT and INR was found between the groups. The mean APTT was significantly lower among the patients presenting with STEMI and non-STEMI (26.58 ± 2.32 s in the STEMI, 26.85 ± 2.41 s in the non-STEMI, 27.64 ± 2.54 s in the unstable, and 27.93 ± 2.53 s in the stable angina groups, respectively, p value = 0.005). After adjustment, the association between the patients' presentations and APTT was significant (OR for 5 s increase in APTT = 1.661, 95% CI = 1.184 to 2.332; p value = 0.003). Conclusion: We observed that the patients who presented with STEMI had the lowest value of APTT, whereas those who presented with stable angina had the highest. The value of APTT in patients undergoing coronary angiography may have a potential to predict the extent and severity of coronary stenosis.

Dose-dependent effect of daptomycin on the artificial prolongation of prothrombin time in coagulation abnormalities: in vitro verification

Background

Several studies have reported that daptomycin induced artificial prolongation of prothrombin time (PT) in some test reagents, particularly in warfarin users. However, it remains unknown whether the artificial prolongation can be affected by coagulation abnormalities other than the use of warfarin. Thus, we investigated the effect of daptomycin on PT with two types of coagulation abnormalities.

Methods

Plasma samples were pooled by four groups: healthy volunteers (Plasma A), warfarin users with a PT-international normalized ratio (INR) of approximately 2.0 (Plasma B) or 3.0 (Plasma C), and patients with liver cirrhosis with a PT-INR of approximately 2.0 (Plasma D). Plasma A was composed of plasma from two healthy individuals (9 mL from each individual). Plasma B, C, and D were composed of plasma from 36 patients (0.5 mL from each patient). Daptomycin was added to each sample to create solutions with several concentrations (0–150 μg/mL). The PT-INR for each solution was measured with three PT reagents. Linear regression analyses were used to determine the association between daptomycin concentration and PT-INR. The relative change in PT-INR due to daptomycin concentrations was calculated.

Results

Strong linear correlations were observed between daptomycin concentrations and PT-INR for all the plasma groups and reagents (R² > 0.7, P < 0.01). At a daptomycin concentration of 150 μg/mL, the relative increase of PT-INR was ≥10% in the majority of the plasma groups with an elevated baseline PT-INR in all reagents tested.

Conclusions

Daptomycin induced the artificial prolongation of PT-INR in a concentration-dependent manner, particularly in plasma samples with an elevated baseline PT-INR. PT should be evaluated at the trough levels of daptomycin.

Effect of Serum Immunoglobulins on Routine Coagulation Tests: A Comparison of Coagulation Analyzers using Mechanical and Optical Clot Detection

BACKGROUND

We previously showed that the prothrombin time (PT), but not activated partial thromboplastin time (APTT), is correlated with serum immunoglobulin level in patients with plasma cell neoplasms.

METHODS

To determine if the observed effect of serum immunoglobulins on PT was reagent and/or method dependent, PT and APTT were measured in plasma samples obtained from patients referred to the Myeloma Institute using mechanical (STAR Evolution; Diagnostica Stago) and optical clot detection (ACL TOP 500 analyzer; Instrumentation Laboratory) and manufacturer provided reagents.

RESULTS

A total of 97 patients were included in this study. Twelve patients had abnormal coagulation test results. An isolated prolonged PT was found in 8 patients and an isolated prolonged PTT was detected in 4 patients.

CONCLUSION

The PT, but not APTT, was positively correlated with serum paraprotein level and this correlation was observed regardless of the reagents and instrumentation used to assess clot time.

Effects of home prothrombin international ratio (PT-INR) management in children with mechanical prosthetic valves - Importance of individual correlations between laboratory and CoaguChek device PT-INRs

BACKGROUND

Warfarin administration is essential but requires difficult management and frequent clinic visits in patients with mechanical prosthetic atrioventricular valve replacement (MPAVVR). This study investigated how home prothrombin international ratio (PT-INR) monitoring with CoaguChek^® (Roche Diagnostics, Basel, Switzerland) safely reduced clinic visits in children with MPAVVR. We also compared individual correlations between the CoaguChek and laboratory PT-INR.

METHODS

This study included four pediatric patients who started frequent warfarin home-monitoring after MPAVVR (three mitral valves and one tricuspid valve). We collected information regarding the number of outpatient clinic visits and measurements of PT-INR before and after starting home CoaguChek monitoring (each one year) from medical records. We also compared individual correlations between laboratory and CoaguChek PT-INR in three patients.

RESULTS

No major clinical events were encountered during the study period. The ratio of outpatient clinic visits in the second year to those in the first year was decreased in all patients (0.30-0.66). The ratio of the numbers of home measurements to all PT-INR measurements in the second year ranged from 0.55 to 0.64 indicating that CoaguChek home monitoring approximately halved the number of outpatient clinic visits. CoaguChek measurements tended to be slightly overestimated in two patients but were greatly underestimated in one patient.

CONCLUSIONS

CoaguChek home monitoring in children with MPAVVR reduced the number of their clinic visits without compromising the safety of warfarin management. Given considerable individual differences in correlations between CoaguChek and laboratory PT-INR, individual correlation needs to be identified to fairly interpret the CoaguChek PT-INR values.

Blood coagulation parameters after intravitreal injection of aflibercept in patients with neovascular age-related macular degeneration

PURPOSE

The aim of this study was to evaluate the effect of intravitreal injection of aflibercept (IVA) on blood coagulation tests in neovascular age-related macular degeneration (AMD) patients.

METHODS

Thirty-four patients with neovascular AMD (study group) and 32 healthy individuals (control group) were enrolled. Prothrombin time (PT) and activated partial thromboplastin time (aPTT) were measured at different times in patients with neovascular AMD.

RESULTS

The levels of PT and aPTT after IVA were decreased at 1 month after the first injection and 1 month after the second injection compared to the baseline measurement in the study group.

CONCLUSIONS

IVA may cause a decrease in the levels of PT and aPTT at 1 month after the first injection and 1 month after the second injection although these results are not statistically significant in our study.

Comparison of different laboratory tests in the evaluation of hemorrhagic risk of patients using rivaroxaban in the critical care setting: diagnostic accuracy study

Background

Rivaroxaban is a direct oral anticoagulant designed to dispense with the necessity of laboratory monitoring. However, monitoring rivaroxaban levels is necessary in certain clinical conditions, especially in the critical care setting.

Methods

This is a diagnostic accuracy study evaluating sensitivity and specificity of prothrombin time (PT), activated partial thromboplastin time (aPTT), and Dilute Russell viper venom time (dRVVT), to evaluate the hemorrhagic risk in patients taking rivaroxaban. The study used a convenience sample of 40 clinically stable patients using rivaroxaban to treat deep vein thrombosis or atrial fibrillation admitted in a private hospital in Brazil, compared to a group of 60 healthy controls. The samples from patients were collected two hours after the use of the medication (peak) and two hours before the next dose (trough).

Results

The correlation with the plasmatic concentration measured by anti-FXa assay was higher for PT and dRVVTS. The PT and aPTT tests presented higher specificity, while dRVVT was 100% sensible.

Conclusions

There was a strong correlation between the tests and the plasma concentration of the drug. Additionally, our results demonstrated the potential use of dRVVT as a screening test in the emergency room and the need of a second test to improve specificity.

Anti-embolic effect of Taorenchengqi Tang in rats with embolic stroke induced by occluding middle cerebral artery

OBJECTIVE

To investigate the anti-embolic effect of Taorenchengqi Tang (TRCQT), a formulas from Traditional Chinese Medicine, plus aspirin in rats with embolic stroke induced by selective occlusion of the middle cerebral artery (MCA). Possible side effects of hemorrhagic incident and other bleeding events and anti-platelet effect were also explored.

METHODS

Ninety rats were randomly separated into 9 groups (n = 10): group 1 a sham-operated group (n = 10); groups 2 and 3 orally treated with an isovolumetric solvent (distilled water) for 1 and 3 months, followed by thromboembolic occlusion (n = 10); groups 4 and 5 orally treated with aspirin (5 mg/kg) alone for 1 and 3 months, followed by thromboembolic occlusion (n = 10); groups 6 and 7 orally treated with TRCQT (0.5 g/kg) alone for 1 and 3 months, followed by thromboembolic occlusion (n = 10); groups 8 and 9 orally treated with TRCQT plus aspirin for 1 and 3 months, respectively followed by thromboembolic occlusion (n = 10). The ischemic stroke in rats was induced by selective MCA occlusion. One was orally administered. After the treatments, rats' brains were removed, sectioned and stained with triphenyltetrazolium chloride (TTC) for infarct volume measurement. The incidence of subarachnoid hemorrhage (SAH) and intracerebral hemorrhage (ICH) were observed. A potential gastric bleeding side effect was assessed by measuring hemoglobin (Hb), and prothrombin time (PT). Collagen-induced platelet activation and tail vein bleeding time were measured.

RESULTS

Treatment with TRCQT alone or in combination with aspirin reduced infarct volume for 1 (P < 0.05), and 3 (P < 0.01) months without SAH and ICH incidences, and gastric bleeding. TRCQT treatment for 1 month was also not altered PT. Moreover, a concentration dependent inhibition of collagen-induced platelet activation, followed by increasing of tail vein bleeding time was observed after TRCQT treatment.

CONCLUSION

Either TRCQT alone or TRCQT plus aspirin exhibits potent neuroprotective effect by reducing infarct volume without changing the status of SAH, ICH and gastric bleeding possibly via inhibiting the platelet activation and increasing bleeding time.

Reduced anticoagulation variability in patients on warfarin monitored with Fiix-prothrombin time associates with reduced thromboembolism: The Fiix-trial

Fiix-prothrombin time (Fiix-PT) differs from traditional PT in being affected by reduced factor (F) II or FX only. In the randomized controlled Fiix-trial, patients on warfarin monitored with Fiix-PT (Fiix-warfarin patients) had fewer thromboembolisms (TE), similar major bleeding (MB) and more stable anticoagulation than patients monitored with PT (PT-warfarin patients). In the current Fiix-trial report we analyzed how reduced anticoagulation variability during Fiix-PT monitoring was reflected in patients with TE or bleeding. Data from 1143 randomized patients was used. We analyzed the groups for anticoagulation intensity (time within target range; TTR), international normalized ratio (INR) variability (variance growth rate B₁; VGR) and dose adjustment frequency. We assessed how these parameters associated with clinically relevant vascular events (CRVE), ie TE or MB or clinically relevant non-MB. TTR was highest in Fiix-warfarin patients without CRVE (median 82%;IQR 72-91) and lowest in PT-warfarin patients with TE (62%;56-81). VGR was lowest in Fiix-warfarin patients without CRVE (median VGR B₁ 0.17; 95% CI 0.08-0.38) and with TE (0.20;0.07-0.26) and highest in PT-warfarin patients with TE (0.50;0.27-0.90) or MB (0.59;0.07-1.36). The mean annual dose adjustment frequency was lowest in Fiix-warfarin patients with TE (mean 5.4;95% CI 3.9-7.3) and without CRVE (mean 6.0; 5.8-6.2) and highest in PT-warfarin patients with TE (14.2;12.2-16.3). Frequent dose changes predicted MB in both study arms. Compared to patients monitored with PT, high anticoagulation stability in Fiix-warfarin patients coincided with their low TE rate. Those with bleeding had high variability irrespective of monitoring method. Thus, although further improvements are needed to reduce bleeding, stabilization of anticoagulation by Fiix-PT monitoring associates with reduced TE.

Dose-dependent artificial prolongation of prothrombin time by interaction between daptomycin and test reagents in patients receiving warfarin: a prospective in vivo clinical study

Background

Daptomycin has been reported to cause artificial prolongation of prothrombin time (PT) by interacting with some test reagents of PT. This prolongation was particularly prominent with high concentrations of daptomycin in vitro. However, whether this prolongation is important in clinical settings and the optimal timing to assess PT remain unclear.

Methods

A prospective clinical study was conducted with patients who received daptomycin for confirmed or suspected drug-resistant, gram-positive bacterial infection at a university hospital in Japan. PT at the peak and trough of daptomycin was tested using nine PT reagents. Linear regression analyses were used to examine the difference in daptomycin concentration and the relative change of PT-international normalized ratios (PT-INR).

Results

Thirty-five patients received daptomycin (6 mg/kg). The mean ± standard deviation of the trough and peak concentrations of daptomycin were 13.5 ± 6.3 and 55.1 ± 16.9 μg/mL, respectively. Twelve patients (34%) received warfarin. With five PT reagents, a significant proportion of participants experienced prolongation of PT-INR at the daptomycin peak concentration compared to the PT-INR at the trough, although the mean relative change was less than 10%. None of the participants clinically showed any signs of bleeding. A linear, dose-dependent prolongation of PT was observed for one reagent [unadjusted coefficient β 3.1 × 10⁻³/μg/mL; 95% confidence interval (CI) 2.3 × 10⁻⁵–6.3 × 10⁻³; p = 0.048]. When patients were stratified based on warfarin use, this significant linear relationship was observed in warfarin users for two PT reagents (adjusted coefficient β, 6.4 × 10⁻³/μg/mL; 95% CI 3.5 × 10⁻³–9.3 × 10⁻³; p < 0.001; and adjusted coefficient β, 8.3 × 10⁻³/μg/mL; 95% CI 4.4 × 10⁻³–1.2 × 10⁻²; p < 0.001). In non-warfarin users, this linear relationship was not observed for any PT reagents.

Conclusions

We found that a higher concentration of daptomycin could lead to artificial prolongation of PT-INR by interacting with some PT reagents. This change may not be clinically negligible, especially in warfarin users receiving a high dose of daptomycin. It may be better to measure PT at the trough rather than at the peak daptomycin concentration.

Comparison between Homocysteine, Fibrinogen, PT, PTT, INR and CRP in Male Smokers with/without Addiction to Opium

BACKGROUND

Regarding the limited studies about effects of addiction on coagulation factors as a risk factor for increasing coagulation, and its relation to coronary artery disease, we decided to investigate the effect of opium on inflammatory and coagulation factors in a controlled setting.

METHODS

This case-control study was performed using two groups of smoking males addicted to opium (27 cases) and not addicted to opium (27 cases). After collecting demographic data, venous blood samples were gathered and sent to laboratory for measuring homocysteine, fibrinogen, prothrombin time (PT), partial thromboplastin time (PTT), International Normalized Ratio (INR), and C-reactive protein (CRP) quantity. In order to analyze the data, we used independent t-test plus Mann-Whitney test with significance level of P < 0.05.

FINDINGS

The average age in this study was 32.2 ± 6.2 in case group and 33.3 ± 6.2 in control group. Comparing case and control groups regarding age and education showed no significant difference (P = 0.598 and P = 0.848, respectively). Mean daily smoking in case group was 7.9 ± 5.4 and 8.1 ± 5.0 in control group. Mean smoking duration in case group and control group was 10.1 ± 6.5 and 9.0 ± 7.2 years, respectively. There was no significant difference between two groups regarding smoking duration (P = 0.567). Comparison of inflammatory and coagulation factors showed no significant difference except for CRP and fibrinogen for which P = 0.661 and P = 0.889, respectively. Consumption-based comparison of inflammatory and coagulation factors showed no significant difference except for PT in oral and inhaled consumptions which showed a significant difference (P = 0.035).

CONCLUSION

Results of this study suggest that opium addiction can be an influential factor in blood parameters and can lead to inflammatory and coagulation processes complications.

Is there any effect of pneumoperitoneum pressure on coagulation and fibrinolysis during laparoscopic cholecystectomy?

BACKGROUND

Laparoscopic cholecystectomies (LC) are generally performed in a 12 mmHg-pressured pneumoperitoneum in a slight sitting position. Considerable thromboembolism risk arises in this operation due to pneumoperitoneum, operation position and risk factors of patients. We aim to investigate the effect of pneumoperitoneum pressure on coagulation and fibrinolysis under general anesthesia.

MATERIAL AND METHODS

Fifty American Society of Anesthesiologist (ASA) I-III patients who underwent elective LC without thromboprophlaxis were enrolled in this prospective study. The patients were randomly divided into two groups according to the pneumoperitoneum pressure during LC: the 10 mmHg group (n = 25) and the 14 mmHg group. Prothrombin time (PT), thrombin time (TT), International Normalized Ratio (INR), activated partial thromboplastin time (aPTT) and blood levels of d-dimer and fibrinogen were measured preoperatively (pre), one hour (post1) and 24 h (post24) after the surgery. Moreover, alanine amino transferase, aspartate amino transferase and lactate dehydrogenase were measured before and after the surgery. These parameters were compared between and within the groups.

RESULTS

PT, TT, aPTT, INR, and D-dimer and fibrinogen levels significantly increased after the surgery in both of the groups. D-dimer level was significantly higher in 14-mmHg group at post24.

CONCLUSION

Both the 10-mmHg and 14-mmHg pressure of pneumoperitoneum may lead to affect coagulation tests and fibrinogen and D-dimer levels without any occurrence of deep vein thrombosis, but 14-mmHg pressure of pneumoperitoneum has a greater effect on D-dimer. However, lower pneumoperitoneum pressure may be useful for the prevention of deep vein thrombosis.

Increased homocysteine plasma level is associated with shortened prothrombin time in HIV-infected patients

OBJECTIVE

To find factors associated with increased homocysteine plasma level in HIV-infected patients.

METHODS

Cross-sectional study, carried out as a supplementary task to the standard care of HIV-infected patients. The possible association of increased homocysteine plasma level with blood analyses results was assessed with a multiple linear regression analysis, using the automatic linear modeling available in SPSS version 22.

RESULTS

A total of 145 patients were included. Creatinine was higher than normal in 7 patients (5%), prothrombin time was shortened in 36 patients (25%), and a monoclonal gammopathy was detected in 2 patients (1%). In the regression analysis, an association was found between high homocysteine plasma level and the following variables: low prothrombin time (β coefficient -0.286, confidence interval -1.1854 to -0.754, p < 0.001), high creatinine (coefficient 9.926, confidence interval 6.351-15.246, p < 0.001), low folic acid (coefficient -0.331, confidence interval -0-483 to -0.187, p < 0.001), and low vitamin B12 (coefficient -0.007, confidence interval -0.01 to -0.001, p = 0.005).

CONCLUSION

An association was found between increased homocysteine plasma level and shortened prothrombin time.

The effects of Ramadan fasting on patients with prosthetic heart valve taking warfarin for anticoagulation

Introduction

Oral anticoagulation with warfarin is indicated for patients with prosthetic heart valves. The effects of religious fasting during Ramadan month (in the Islamic calendar) on anticoagulation aren’t clear.

Objectives

To study the impact of Ramadan fasting on international normalized ratio (INR), quality of anticoagulation, dose of warfarin used and blood osmolarity.

Methods

18 patients were followed-up prospectively for 3 months (pre- Ramadan, Ramadan and post-Ramadan months). Patients presented for weekly visits in which blood samples were obtained.

Results

No significant difference in INR and warfarin dose was found between Ramadan month, and months before and after it. The post-Ramadan INR was significantly larger than pre-Ramadan (p = 0.004). Blood osmolarity was significantly lower during Ramadan compared to pre- and post-Ramadan months. A significantly better quality of anticoagulation was noticed during Ramadan (p < 0.001). A significantly larger ratio of supratherapeutic INR values occurred in the post-Ramadan month (p < 0.05). A significantly larger ratio of infra-therapeutic INR values was noticed in the pre-Ramadan month (p < 0.05).

Conclusion

No significant difference in mean INR or warfarin dose was found and a better quality of anticoagulation was achieved during Ramadan. A tendency toward supra-therapeutic anticoagulation occurred after Ramadan, thus a closer follow up during this period may be reasonable.

Study of Basic Coagulation Parameters among HIV Patients in Correlation to CD4 Counts and ART Status

INTRODUCTION

HIV infection is known to cause coagulation abnormalities by various mechanism, especially during its late course.

AIM

The objective of this study was to analyse platelet count, prothrombin time and activated partial thromboplastin time among HIV infected patients and to analyse these parameters with respect to their CD4 count and ART status.

MATERIALS AND METHODS

A case control study was conducted with 120 HIV infected patients and 40 normal individuals. The blood samples were collected after obtaining consent from the subjects. The blood samples were processed for platelet count, prothrombin time and activated partial thromboplastin time and CD4 count. The results were tabulated and analysed with statistical package.

RESULTS

The platelet count was significantly decreased in HIV infected patients compared to controls. Though HIV patients with CD4 count less than 200cells/mm(3) showed a decreased platelet count compared to those with CD4 count greater than 200cells/mm(3), it was not statistically significant. Prothrombin Time (PT) and Activated Partial Thromboplastin Time (aPTT) was significantly prolonged in HIV patients, but only aPTT showed significant inverse correlation with CD4 count. None of the parameters showed statistical significance on comparing HIV patients on ART with those not on ART.

CONCLUSION

Basic coagulation tests like platelet count, PT and especially aPTT can be used as prospective screening test to assess severity in HIV patients in resource limited settings where CD4 count is not available.

Changes in coagulation functions and hemorheological parameters may predict hematoma formation after total knee arthroplasty

BACKGROUND

Hematoma formation around the knee is commonly seen after total knee arthroplasty (TKA) and may cause patient discomfort and worry regarding the success of the surgery. This study aimed to evaluate the coagulation functions and hemorheological parameters in patients undergoing TKA and investigate their associations with hematoma formation.

METHODS

This study prospectively included 146 patients treated for knee osteoarthritis by unilateral TKA between August 2013 and August 2014. Apixaban was administered twice during the 12-24-h period after surgery. Blood coagulation functions were evaluated according to activated partial thromboplastin time (APTT), prothrombin time (PT), thrombin time, and fibrinogen preoperatively and on postoperative days 1, 3, 7, and 14. Hemorheological parameters were also measured. Patients were divided into a hematoma group and a non-hematoma group for comparison.

RESULTS

On postoperative day 1, the hematoma group showed significantly prolonged APTT and PT and significantly decreased hematocrit relative to baseline values (P < 0.05). The whole blood high shear rate, whole blood low shear rate, plasma viscosity, and hematocrit did not differ significantly between the two groups at baseline or from postoperative days 1-14 in (P > 0.05).

CONCLUSIONS

Prolonged APTT and PT on the first day after TKA as well as decreased hematocrit may indicate an increased risk of hematoma formation. Postoperative use of apixaban may promote the formation of ecchymoses but is not a major contributing factor.

Comparison of prothrombin time tests used in the monitoring of edoxaban and their evaluation as indicators of the reversal effect

Clinical demand for the prompt assessment of the activity of direct-acting factor Xa inhibitors in the emergency care setting is increasing. In the present study, we examined whether prothrombin time (PT) tests can serve as a clinically useful indicator of anti-factor Xa activity. In the first series, the in vitro effect of edoxaban on PT was evaluated by spiking human plasma with edoxaban and measuring PT using three different commercial PT tests. In the second series, the reversal effect of prothrombin complex concentrates (PCC) and activated PCC (aPCC) in edoxaban-spiked plasma was evaluated. In the third series, PT of plasma samples from patients administered either 15 or 30 mg/day of edoxaban was assessed, and the results were compared with edoxaban concentrations determined by a calibrated anti-factor Xa activity assay. The spike test revealed that all PT reagents positively correlated with edoxaban. The sensitivity to edoxaban varied among the three reagents and Triniclot(®) Excel S showed the best performance. Prolonged PT by edoxaban was reversed by PCC and aPCC in a dose-dependent manner; however, complete reversal was not achieved. Positive correlation between anti-factor Xa activity and PT was shown in the clinical samples at the edoxaban range from 0 to >300 ng/mL.

Preoperative D-dimers as an independent prognostic marker in cervical carcinoma

Activation of coagulation and fibrinolysis has been observed in many tumors. Our study aimed to investigate the clinical and prognostic significance of various plasma coagulation tests in patients with cervical cancer. A total of 296 patients with cervical cancer were included in the analysis. Patients were followed up for at least 60 months until death. Pretreatment parameters including activated partial thromboplastin time, D-dimer, fibrinogen, prothrombin time, thrombin time, lactate dehydrogenase, and squamous cell carcinoma antigen were evaluated. Prothrombin time (hazard ratio = 1.825; P = 0.006) and plasma D-dimer levels (hazard ratio = 2.179; P = 0.036) were identified as significant independent predictors of overall survival. Patients with elevated D-dimer levels had a significantly shorter overall survival compared with those with low-D-dimer levels (<0.5 μg/ml) in the stage I subgroup (n = 98, P = 0.019) and stage II subgroup (n = 77, P = 0.044). D-dimer levels differed significantly according to mortality (P < 0.001), stage I versus stage II (P = 0.030), and stage I versus stage III/IV (P = 0.038). DD level of patients with chemotherapy and/or radiotherapy was higher than patients with other treatment (P < 0.001). Patients with a low-D-dimer level (<0.5 μg/ml) showed a significantly better 5-year overall survival (OS) compared with patients with an increased D-dimer level for different histological typing of squamous cell carcinoma (SCC) (P = 0.001) and non-SCC (P < 0.043). In conclusion, the pretreatment plasma D-dimer level is a potential prognostic factor for cervical cancer.

How the direct oral anticoagulant apixaban affects thrombin generation parameters

BACKGROUND AND OBJECTIVES

Apixaban is a direct oral anticoagulant (DOAC) targeting factor Xa and thus quenching thrombin generation and clot formation. However, little information is available on the influence that apixaban may have on the parameters of thrombin generation.

METHODS

Aliquots of a pooled normal plasma have been added with increased concentrations of purified apixaban and were used to assess the degree of modification brought about by the drug on the basic tests of coagulation prothrombin and activated partial thromboplastin time (PT and APTT) and on thrombin generation parameters.

RESULTS

The study shows that while apixaban has little effect on PT or APTT it does affect all the parameters of thrombin generation, including the lag-time (which is increased), the endogenous thrombin potential (ETP) and thrombin-peak (both decreased although to a different extent), and the velocity index (decreased). Interestingly, the above effects were more pronounced when the measurements were recorded in the presence of thrombomodulin, thus making the ratio (with/without thrombomodulin) to decrease consistently as a function of the apixaban concentrations.

CONCLUSIONS

These findings support the antithrombotic properties of apixaban and can help to understand the mechanism(s) of action of this drug. Thrombin generation could be used as a convenient laboratory tool to assess the anticoagulant activity of other drugs and to make between-DOAC comparison.

Identification of anthranilamide derivatives as potential factor Xa inhibitors: drug design, synthesis and biological evaluation

The coagulation enzyme factor Xa (fXa) plays a crucial role in the blood coagulation cascade. In this study, three-dimensional fragment based drug design (FBDD) combined with structure-based pharmacophore (SBP) model and structural consensus docking were employed to identify novel fXa inhibitors. After a multi-stage virtual screening (VS) workflow, two hit compounds 3780 and 319 having persistent high performance were identified. Then, these two hit compounds and several analogs were synthesized and screened for in-vitro inhibition of fXa. The experimental data showed that most of the designed compounds displayed significant in vitro potency against fXa. Among them, compound 9b displayed the greatest in vitro potency against fXa with the IC50 value of 23 nM and excellent selectivity versus thrombin (IC50 = 40 μM). Moreover, the prolongation of the prothrombin time (PT) was measured for compound 9b to evaluate its in vitro anticoagulant activity. As a result, compound 9b exhibited pronounced anticoagulant activity with the 2 × PT value of 8.7 μM.

Laboratory measurements of the oral direct factor Xa inhibitor edoxaban: comparison of prothrombin time, activated partial thromboplastin time, and thrombin generation assay

OBJECTIVES

Edoxaban, an oral direct factor Xa inhibitor, does not require routine monitoring. However, assessment of the anticoagulant effects may be required in certain situations.

METHODS

We investigated the effects of edoxaban on prothrombin time (PT), activated partial thromboplastin time (aPTT), and thrombin generation using human platelet-poor plasma (PPP) or platelet-rich plasma (PRP).

RESULTS

Edoxaban concentration-dependently prolonged PT and aPTT. There was a considerable variation in the magnitude of PT prolongation among the reagents used. The variability in aPTT prolongation among the reagents was smaller than that of PT. Edoxaban concentration-dependently inhibited thrombin generation, with a more potent effect seen in PPP than in PRP. Thrombin generation assay was three times more sensitive to edoxaban than PT and aPTT.

CONCLUSIONS

PT had disadvantages of a large variability among different PT reagents. aPTT could be used as a conventional and convenient test with a smaller variation among reagents. Thrombin generation was the most sensitive assay.