Clot characterization by multidisciplinary approach: biochemical and imaging parameters in a hypocoagulative setting. A pilot study.

BACKGROUND: Clot characterization is, to the present days, a multimodal approach: scanning the clot by electron microscopy (SEM) is helpful for the visualization of fibrin structure along with laboratory parameters such as the clot waveform analysis (CWA) and thrombin generation in different settings of clot abnormalities. This study aimed to assess whether the coagulative parameters were consistent with the clot images texture acquired by SEM, and therefore to propose a more generalist and integrative approach to clots classification. DESIGN AND METHODS: In this pilot study, the examined population consists of eight healthy subjects, seven patients affected by Acquired Hemophilia A (AHA) and seven patients treated with Vitamin K Antagonists (VKAs), similar for age and gender. We studied the velocity and acceleration (1st and 2nd derivative of the aPTT) of clot formation (CWA), the thrombin generation, and the clots' scanning by SEM. Images acquired with SEM were then analyzed with the MATLAB software with the "Texture Analysis" methods to perform classification. Among the various texture parameters, we reported Contrast and Energy. RESULTS: Significant differences among healthy subjects, patients with AHA and those treated with VKAs were detected for the coagulative parameters. We found no differences between VKAs and AHA patients. Contrast and energy highlighted a significant difference among the three groups in agreement with the laboratory's parameters. We found no significant differences between VKAs and AHA patients. CONCLUSIONS: The use of SEM, CWA and thrombin generation parameters may be a starting point for studies aimed to demonstrate the general characteristics of clot formation in different clinical conditions with a multiparametric approach.

Point-of-care testing INR: an overview.

Oral anticoagulant therapies with the anti-vitamin K drugs (AVK), warfarin, acenocoumarol and phenprocoumon, are employed in primary and secondary anti-thrombotic prophylaxis in patients with venous thromboembolism, atrial fibrillation and cardiac mechanical valves. However, a monitoring test such as the International Normalized Ratio (INR) is required. The periodic monitoring of this therapy entails discomfort for the patients. Telemedicine and telecare can provide significant aid in the management of this therapy allowing patients to perform the test at home or anywhere else with a portable device, i.e. point-of-care testing (POCT), and to send the result to a thrombosis (TC) via web. Patients can receive dose adjustment sent back by the TC. The effectiveness of this type of management is equal or superior to the traditional AVK monitoring in terms of hemorrhagic and thrombotic events. Analysis of the costs with a horizon of 10 years reveals that both self-testing and self-management are cost-effective. The aim of this overview is to describe the pros and cons of the use of POCT as an alternative in the monitoring of AVK. In particular, description of the POCT, decentralization, quality of the therapy, safety and costs will be examined.

The criteria of the Italian Federation of Thrombosis Centres on DOACs: a "real world" application in nonvalvular atrial fibrillation patients already on vitamin K antagonist.

The aim of this study was to evaluate the number of patients with nonvalvular atrial fibrillation (NVAF), anticoagulated with vitamin K antagonists (VKA), and monitored in our Thrombosis Centre, who could replace VKA with direct oral anticoagulants (DOACs) based on the Italian Federation of Thrombosis Centres (FCSA) consensus criteria. A total of 525 NVAF patients treated with VKA were studied. Therapeutic range (TTR) assessment and a capillary test for serum creatinine measure were carried out. The patients' preference was evaluated through the administration of a dedicated questionnaire. A history of intracranial bleeding was also taken into account. DOACs would cover 29 % of the patients considering a TTR <70 %; the percentage falls to 10 % if a TTR <55 % is considered. Only 20 % of the patients would move from VKA to DOACs because of the lack of an antidote and laboratory checks during DOACs therapy. Thirty-three percent of patients were worried that they would forget to take the tablets twice a day. About 2 % of patients could not use DOACs since their glomerular filtration rate was less than 30 ml/min, while in 23.6 %, a reduction in the daily dose of DOACs would have been required due to renal failure. TTR assessment, renal function and a previous history of intracranial bleeding would reduce the percentage of patients who could switch from VKA to DOACs, but it is the patients' preference that strongly influences the percentage of those who would benefit from DOACs treatment. However, if laboratory controls were available, it would rise considerably.

Telemedicine can improve the quality of oral anticoagulation using portable devices and self-testing at home.

Point-of-care testing (POCT) devices can be used to monitor anticoagulant therapy. We compared patients being monitored at home by self-testing using a POCT device and telemedicine support with a previous period of conventional monitoring at a Thrombosis Centre. A total of 114 anticoagulated patients participated. The number of blood checks (INR) was significantly higher in the home monitoring group and the interval between checks was significantly shorter. The percentage of missed INR checks was significantly higher during the conventional monitoring period compared with home monitoring. Patients were divided into two groups on the basis of the time spent within the therapeutic range (TTR) during conventional monitoring: the unstable group had TTR<70% and the stable group had TTR ≥70%. In the unstable group there was a significant increase in TTR with home monitoring: 63% to 68% (P < 0.001) while in the stable group there was no significant change (77% to 75%). The study showed that oral anticoagulation management by means of self-testing is suitable and safe.

Point-of-care (POCT) prothrombin time monitors: is a periodical control of their performance useful?

INTRODUCTION: Point-of-care testing (POCT) prothrombin time monitors are now widely used to monitor oral anticoagulant treatment. Although portable coagulometers are extremely easy to use, checking the quality of their performance presents some difficulties. MATERIALS AND METHODS: The aims of this study were to investigate on a quarterly basis the performance of 95 Coagucheck S assigned to 99 anticoagulated patients at home. This was done checking the monitors versus a reference coagulometer in the laboratory at our Thrombosis Centre (TC). The other aims were to carry out an external quality assessment employing different sets of INR certified plasmas with 5 different ranges of anticoagulation and to assess the performance of the different lots of strips employed by the patients during the study. RESULTS: No difference between the PT INR obtained with both the systems at the first quarterly check was noted but a significant difference was found when the two systems were compared at the second and third quarterly checks. The Bland-Altman test showed increased disagreement between the first and the third controls. The percentage of INR values that showed a difference of more or less than 0.5 INR units in the PT values performed with both the systems was: 1.0% (first control), 7.5% (second control) and 11.5% (third control) (Chi-Square: 8.315, p=0.0156). Lots with differences higher than 10% in terms of +/- 0.5 INR Units at the first, second and third controls were 16%, 20.8% and 61%, respectively. Seven monitors (7.3%) failed to test one or two of the INR certified plasmas of one set but performed well using a second set of plasmas. Three monitors (3.1%) failed to test two sets of plasmas but performed well using a different lot of strips (from 279A to 483A). One monitor (1%) gave unsatisfactory results with different sets of plasmas and strips. All the other PT INR obtained with the monitors fell well within the different ranges of the INR certified plasmas. CONCLUSIONS: Anticoagulated patient in self-testing or self-management should periodically bring their portable coagulometer to a reference Thrombosis Centre especially when the lot of strips have to be changed. The role of Thrombosis Centre appears therefore crucial in this regard.

[Amoxicillin-clavulanic acid and oral anticoagulants: a possible dangerous association]. / Amoxicillina-acido clavulanico ed anticoagulanti orali: un'associazione potenzialmente pericolosa.

We describe a 68-year-old male patient, treated with amoxicillin-clavulanic acid for 18 days and oral anticoagulants. He developed a cholestatic hepatitis with conjugated bilirubin of 11 mg/dL and a concomitant overdose of oral anticoagulants (INR 7). Nausea, vomiting, jaundice and large ecchymoses occurred 41 days after treatment with amoxicillin-clavulanic acid; the clinical manifestations resolved within 1 week and the liver tests returned to normal 48 days after therapy withdrawal. The mechanism of the amoxicillin-clavulanate-induced hepatitis is probably immunoallergic; this complication occurs mainly in subjects with a metabolic and/or immunologic idiosyncrasy. The pharmacokinetics of this antibiotic, which is not directly metabolized by cytochrome P450, may be affected by the concomitant use of drugs under cytochrome P450 control. When using amoxicillin-clavulanic acid, one should take into account its potential hepatic toxicity and possible interaction with oral anticoagulants. However, it appears to be crucial to follow the correct indications for both drugs. In fact, in the patient described above amoxicillin-clavulanic acid was wrongly administered as prophylaxis after a cutaneous biopsy of the nose. The same occurred with the oral anticoagulants prescribed to the patient for a single episode of paroxysmal atrial fibrillation which had occurred one year previously.

Allele 4G of gene PAI-1 associated with prothrombin mutation G20210A increases the risk for venous thrombosis.

Several studies have tried to clarify the role of polymorphism 4G/5G of the PAI-1 gene in venous thromboembolism without reaching any final conclusion. It has been demonstrated that this polymorphism may induce an increased risk for venous thromboembolism (VTE) in patients with thrombophilic defects. We studied the association of prothrombin mutation G20210A with 4G/5G polymorphism in 402 VTE patients and 466 healthy controls. Patients affected by prothrombin mutation G20210A, with or without the concomitant presence of allele 4G, had a 3.7 thrombotic risk (C.I. 95% 2.3-6.0; p<0.0001). Moreover, genotype 4G/4G is a mild risk factor for VTE, irrespectively of whether the prothrombin mutation was present. Logistic regression analysis showed that patients carrying the G20210A prothrombin mutation with allele 4G gave an odds ratio for VTE of 6.1 (C.I. 95% 3.2-11.4; p<0.001). The risk increased up to 13.0 (C.I. 95% 3.0-60.4; p<0.001) when we considered the association of the prothrombin mutation with genotype 4G/4G. The G20210A mutation without allele 4G (5G/5G) was not a risk factor for VTE. In conclusion, we believe that patients affected by VTE with concomitant presence of the G20210A prothrombin mutation could be tested for genotype 4G/4G to better define their thrombotic risk.

Hyperhomocysteinemia: could the post-methionine oral loading test sometimes be avoided?

BACKGROUND AND OBJECTIVES: Measurement of homocysteinemia, a risk factor for venous and arterial thrombosis, is carried out in patients fasting for 12 hours and after an oral methionine load (PML). The procedure is time-consuming and several of the patients suffer from nausea and malaise. We wondered whether methionine loading could sometimes be avoided by considering fasting homocysteinemia (tHcy) levels. DESIGN AND METHODS: We evaluated whether fasting tHcy levels were useful to predict PML and deltaPML tHcy with acceptable sensitivity and specificity in 381 patients with venous and arterial thrombosis through the generation of receiver operating characteristic curves. RESULTS: Both PML and deltaPML tHcy correlated with fasting tHcy values. The cut-off of fasting tHcy value yielding a 100% sensitivity in predicting normal PML and deltaPML tHcy was 6.5 and 5.0 micromol/L in females, and 7.1 and 7.2 micromol/L in males. Fasting tHcy values yielding a 95% specificity in predicting a positive PML and tHcy result ranged from 12.5 to 13.1 micromol/L in males and from 10.4 to 10.5 micromol/L in females. A 95% specificity in predicting a positive deltaPML tHcy result ranged from 10.8 to 11.6 micromol/L in females and from 15.9 to 17.0 micromol/L in men. Considering PML tHcy, 186 out of 381 patients could have avoided methionine loading while using deltaPML tHcy 123 out of 381 could have done so. INTERPRETATION AND CONCLUSIONS: Nearly 50% of our patients considering PML tHcy, and about 30% considering deltaPML tHcy could have been spared the methionine loading test. We propose this model for those who wish to carry out this analysis on their own.