Effect of low-intensity warfarin anticoagulation on level of activity of the hemostatic system in patients with atrial fibrillation. BAATAF Investigators

Comparisons of Edoxaban Versus Warfarin on Levels of Plasma Prothrombin Fragment in Patients With Nonvalvular Atrial Fibrillation

The effect of edoxaban on plasma prothrombin fragment 1+2 (PTF1+2), a sensitive maker of in vivo thrombin generation, has not been fully investigated in nonvalvular atrial fibrillation (NVAF). We compared plasma PTF1+2 levels between 25 NVAF patients receiving warfarin and 100 NVAF patients receiving edoxaban and additionally analyzed the association between plasma PTF1+2 levels and the dose of edoxaban. Plasma PTF1+2 levels were significantly higher in patients receiving edoxaban than in those receiving warfarin (141.5 ± 50.0 pmol/l vs 93.1 ± 55.7 pmol/l, p < 0.001). The prevalence of plasma PF1+2 levels above the upper limit (229 pmol/l) of the normal range did not differ between the 2 groups (4% vs 4%), whereas the prevalence of plasma PTF1+2 levels below the lower limit (69 pmol/l) of the normal range was significantly lower in patients receiving edoxaban than in those receiving warfarin (1% vs 48%, p < 0.001). Multiple linear regression analysis identified age and warfarin treatment as independent variables associated with the plasma PTF1+2 level. In a subgroup analysis, plasma PTF1+2 levels were significantly higher in 58 receiving edoxaban of 30 mg/day than in 42 receiving edoxaban of 60 mg/day (157.6 ± 50.8 pmol/l vs 121.6 ± 39.8 pmol/l, p = 0.01); however, after adjusting for confounding factors, the dose of edoxaban was not independently associated with the plasma PTF1+2 level. In conclusion, edoxaban sufficiently inhibits thrombin generation unrelated to its dose in NVAF, although its inhibitory effect is weaker compared with warfarin.

Anticoagulation Therapy for Non-valvular Atrial Fibrillation: A Mini-Review

Anticoagulation therapy is an important method of preventing stroke in individuals with atrial fibrillation (AF). Atrial fibrillation is a quivering or irregular heartbeat that can lead to blood clots, stroke, heart failure, and other heart-related complications. Clinical guidelines on AF consistently recommend long-term oral warfarin to treat valvular atrial fibrillation (VAF). However, due to varying risks of blood clots and stroke associated with different types of non-valvular atrial fibrillation NVAF, it is unclear whether direct oral anticoagulant (DOAC) can replace warfarin. Despite a recent increase in evidence on the effectiveness and the importance of anticoagulant therapy in preventing thromboembolic events associated with NVAF, clinical prevention strategies remain complex. Given the complexities associated with clinical use of anticoagulants for patients with NVAF, this review aims to offer guidance on patient anticoagulant use based on current available evidence.

Prevalence of atrial fibrillation, oral anticoagulation prescription and associated factors in Brazilian older adults

INTRODUCTION: Atrial fibrillation increases five times the risk of stroke. Anticoagulation reduces the incidence of cerebrovascular events. However, many patients do not receive thromboprophylaxis. OBJECTIVES: To estimate the prevalence of atrial fibrillation in the elderly at a Brazilian university hospital and the proportion of anticoagulation prescription. Secondary objectives were to identify the therapeutic options, the main reasons for non-prescription and the factors associated with ineffectiveness or lack of treatment. METHOD: cross-sectional study with a consecutive sample of 1,630 outpatients selected at Hospital de Clínicas de Porto Alegre between April and June of 2017. Atrial fibrillation was identified in 220 (13.50%) individuals. Medical records from 145 patients were accessed, followed by a telephone interview. The association between variables and outcomes was checked using the Mann-Whitney’s U Test and the binary logistic regression. RESULTS: The prevalence of atrial fibrillation was 13.50%. Anticoagulation therapy was prescribed in 77.93% of cases. In 76.11% of patients, warfarin was the chosen drug. There was a tendency towards no prescription in patients with previous bleeding (RR = 2.32; 95%CI 0.95 – 5.64; p = 0.06) and falls (RR = 2.02; 95%CI 0.82 – 5.03; p = 0.08). We found an association between reduced functional capacity (Barthel’s Activities of Daily Living Score < 80) and higher rate of anticoagulation in therapeutic aim (RR = 0.22; 95%CI 0.06 – 0.87; p = 0.04). CONCLUSION: The prevalence of atrial fibrillation in this population was 13.50% and in 77.93% of cases anticoagulant were prescribed. Functional impairment was associated with a higher rate of anticoagulation in therapeutic aim.

Effects of anticoagulation on markers of activation of clotting following major orthopedic surgery

INTRODUCTION

This study examines makers of activation of clotting following three chemoprophylactic regimens used for prevention of postoperative venous thromboembolic disease (TED) following high-risk surgery for TED.

METHODS

Patients having elective primary knee or hip replacement surgery received variable dose warfarin (target international normalized ratios 2.0-2.5), 1 mg warfarin daily starting 7 days preoperatively or aspirin 325 mg daily starting on the day of surgery. Twelve patients in each group were treated for 28 ± 2 days. Thrombin-antithrombin (T-AT) and prothrombin fragment F1 + 2 were measured at baseline and postoperative days 3 and 28 ± 2.

RESULTS

Thrombin-antithrombin and F1 + 2 on postoperative day 3 were equal for the study groups. By days 28 ± 2, variable dose warfarin therapy group suppressed production of F1 + 2 (P = 0.002) with no difference in the T-AT accumulation. F1 + 2 for other patients overlapped the normal range.

CONCLUSION

The signals of activated clotting following surgery did not differentiate the three regimens on postoperative day 3. Variable dose warfarin was associated with suppression of F1 + 2 after 1 month of therapy, with no effect on accumulation of T-AT. Fixed low-dose warfarin started 7 days prior to surgery and aspirin are not inferior on postoperative day 3, but appear to be inferior over a longer treatment.

Challenges of Older Patients’ Knowledge About Warfarin Therapy

Objective: To review the challenges of warfarin education for older patients (aged 65 years or older) in terms of knowledge, access to warfarin education, and education resources. Methods: A quasi-systematic review of the literature was performed via electronic database searches (eg, Medline, Embase, Cumulative Index to Nursing and Allied Health Literature, International Pharmaceutical Abstracts, Meditext, and Google Scholar) from 1990 to May 2011. Results: The 62 articles reviewed found that improved patient knowledge results in better anticoagulation control. The review also found that between 50% and 80% of older patients have inadequate knowledge about the basic aspects of warfarin therapy (eg, action, benefits and risks, interactions with other drugs or foods, international normalized ratio management). Demographic factors, such as advancing age, lower family income, and limited health literacy, were found to inversely affect patients’ warfarin knowledge, and access to warfarin education and information resources were often suboptimal in different practice settings. Finally, a number of educational strategies and resources that could be readily incorporated to improve the effectiveness of current warfarin education programs were extracted from the review. Conclusion: This comprehensive review highlights that education about warfarin in older patients is currently suboptimal and may in part contribute to poor therapeutic outcomes. This review article also acknowledges the need to identify, target, and develop educational strategies and resources to further improve older patients’ knowledge about their warfarin therapy.

Accumulation of risk factors enhances the prothrombotic state in atrial fibrillation

BACKGROUND

The present study was conducted to investigate the relation between the accumulation of the risk factors of thromboembolism and the levels of hemostatic markers in patients with nonvalvular atrial fibrillation (NVAF).

METHODS

Five hundred ninety-one NVAF patients and 129 control subjects were categorized into low, moderate or high risk of thromboembolism, according to CHADS(2) index. One point each was given to patients with advanced age (> or =75 years), hypertension, congestive heart failure, and diabetes mellitus, and 2 points, to those with prior ischemic stroke or transient ischemic attack. Patients with CHADS(2) score of 0, 1 or 2, and > or =3 were classified as low, moderate and high risk, respectively. Levels of hemostatic markers (platelet factor 4, beta-thromboglobulin, prothrombin fragment F1+2 and D-dimer) were determined.

RESULTS

Of 591 patients with NVAF, 302 were treated with warfarin (mean international normalized ratio 1.88). D-dimer levels increased as the risk level increased irrespective of warfarin use. Particularly, NVAF patients without receiving warfarin (n=289) had significantly higher D-dimer levels than control patients (e.g., for high risk patients, 175+/-144 vs 75+/-87 ng/ml, p<0.001), while NVAF patients receiving warfarin had intermediate levels (136+/-156 ng/ml). F1+2 levels increased as the risk level increased, and were significantly suppressed by warfarin. Levels of markers of platelet activation (platelet factor 4 and beta-thromboglobulin) were increased in NVAF patients but not affected by the risk level.

CONCLUSION

Coagulation and fibrinolytic activity is increased along with the accumulation of the risk factors of thromboembolism in NVAF patients.

Dementia in subjects with atrial fibrillation: hemostatic function and the role of anticoagulation

BACKGROUND

Atrial fibrillation (AF) is associated with cognitive impairment and dementia, perhaps through encouraging a prothrombotic state and cardioembolism.

OBJECTIVES

We wished to test the hypotheses that hemostatic function is altered in subjects with AF who develop dementia, and that long-term warfarin anticoagulation is protective against this complication.

PATIENTS AND METHODS

Recruitment was from an observational cohort study of AF. Baseline assessment included measurement of plasma fibrinogen, fibrin D-dimer, prothrombin fragment 1+2 (F1+2), thrombin-antithrombin complexes (TAT), von Willebrand factor and tissue plasminogen activator. We assessed cognitive function after 3 years' follow-up using the 13-item modified Telephone Interview for Cognitive Status (TICSm) and the short form of the Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE).

RESULTS

Of the 218 subjects assessed, 145 (66%) were prescribed warfarin. Forty-nine (22%) met TICSm/IQCODE criteria for dementia. D-dimer, F1+2 and TAT levels were higher in AF subjects with dementia compared with those without (medians 81 vs. 60 ng mL(-1), P = 0.008; 0.76 vs. 0.49 nmol L(-1), P = 0.006; and 1.78 vs. 1.44 microg L(-1), P = 0.003, respectively). These associations became of borderline statistical significance following adjustment for age. Logistic regression showed a trend towards warfarin use being independently associated with reduced prevalence of dementia (odds ratio 0.52, P = 0.08).

CONCLUSIONS

We found evidence of increased thrombin generation and fibrin turnover in subjects with AF and dementia compared with those without dementia. Long-term warfarin use may be protective against the development of dementia in subjects with AF.

Prothrombotic Activity Is Increased in Patients With Nonvalvular Atrial Fibrillation and Risk Factors for Embolism

STUDY OBJECTIVES

The aim of this study was to investigate whether risk factors for embolism would promote thrombus formation in patients with nonvalvular atrial fibrillation (NVAF).

METHODS

Hemostatic markers for platelet activity (ie, platelet factor-4 and beta-thromboglobulin [TG]), thrombotic status (ie, prothombin fragments 1 and 2), and fibrinolytic status (ie, d-dimer) were determined in 246 patients with NVAF (mean age, 66.1 years) and 111 control subjects without NVAF (68.3 years).

RESULTS

The beta-TG level was higher in NVAF patients than in control subjects. D-dimer levels were higher in NVAF patients having risk factors (mean [+/- SE] d-dimer level, 158.6 +/- 9.2 ng/mL) than in those without risk factors (mean d-dimer level, 92.1 +/- 6.7 ng/mL; p < 0.01) and in control subjects (mean d-dimer level: control subjects with risk factors, 79.1 +/- 10.3 ng/mL; control subjects without risk factors, 31.0 +/- 7.4 ng/mL; p < 0.01). NVAF (odds ratio [OR], 3.94; 95% confidence interval [CI], 1.87 to 8.30; p = 0.0003) and age of >/= 75 years (OR, 5.68; 95% CI, 2.87 to 11.23; p < 0.0001) emerged as predictors of elevated levels of d-dimer, and only NVAF (OR, 10.30; 95% CI, 5.67 to 18.72; p < 0.0001) emerged as a predictor of elevated levels of beta-TG.

CONCLUSIONS

NVAF patients whose conditions were complicated with risk factors for embolism could be in the prothrombotic state. Advanced age is a strong predictor of the prothrombotic state in NVAF patients.

[Identification of factors responsible for oral over-anticoagulation in outpatients with heart disease]

BACKGROUND

Few studies have attempted to investigate the clinical course or identify factors responsible for excessive anticoagulation in patients with heart disease.

OBJECTIVES

To determine the incidence of excessive anticoagulation in outpatients with heart disease treated with acenocoumarol, analyze the factors related with over-anticoagulation, and identify bleeding complications.

PATIENTS AND METHOD

This 7-month prospective observational study included consecutive outpatients anticoagulated with acenocoumarol. They were seen in an anticoagulation unit. The high INR group of 55 over-anticoagulated patients had at least one test with INR > 5. The control group of 49 patients had INR results strictly within therapeutic range.

RESULTS

A total of 3,683 INR determinations were made in 512 patients. Seventy-seven tests had an INR > 5 (a 2% overall incidence of high-INR). In the group of 55 INR < 5 patients, 31% had more than one INR determination > 5 during follow-up. Multivariate analysis identified four variables as independent predictors of over-anticoagulation: artificial heart valve, poor treatment compliance, addition of potentially interactive new drugs, and illness in the last month. The high-INR group patients had more bleeding episodes (21.8 vs 4.08%; p = 0.008), one of which was major.

CONCLUSION

The incidence of excessive oral anticoagulation in our outpatient population was similar to that reported in other studies. Patients with INR > 5 had more total bleeding complications, mostly minor. It is recommended to proceed carefully with oral anticoagulant therapy in patients with an artificial heart valve, suspected poor treatment compliance, addition of potentially interactive new drugs, and illness in the last month.

Anticoagulation and minor oral surgery: should the anticoagulation regimen be altered?

PURPOSE

This study was performed to assess the extent of bleeding in anticoagulated patients undergoing minor oral surgery procedures when compared with patients who stop their anticoagulation regimen before surgery and patients who have never been anticoagulated.

MATERIALS AND METHODS

Patients on anticoagulant medications undergoing dentoalveolar surgery procedures either stopped their anticoagulation regimen 72 to 96 hours before the planned surgical intervention or continued their regular regimen throughout the time of surgery. Blood loss was measured by weighing sponges used in the procedures, and groups were compared for differences in blood loss. They were also compared with an additional control group that had never been on anticoagulant therapy.

RESULTS

There was no difference in blood loss detected among any of the experimental or control groups. No bleeding complications occurred in any anticoagulated patient.

CONCLUSIONS

The data suggest that many patients can safely undergo routine outpatient oral surgical procedures without alteration of their regular therapeutic anticoagulation regimens and without additional medical intervention. However, a larger experimental population may be needed to elucidate the appropriateness of this approach to perioperative care.

[Improvement in fibrinolytic function following anticoagulant treatment in chronic rheumatic atrial fibrillation]

INTRODUCTION AND OBJECTIVES

Patients with rheumatic atrial fibrillation are considered at high risk of systemic embolism and require oral anticoagulation. Fibrinolytic function has been little studied. We evaluated fibrinolytic activation markers before starting anticoagulation, at 1 and 6 months following the introduction of oral anticoagulation therapy. We analyzed the relationship with left atrial diameter and mitral area.

METHODS

Tissue plasminogen activator (tPA), its inhibitor (PAI-1), plasmin-antiplasmin complexes (PAP) and D-dimer were measured in 13 patients with rheumatic atrial fibrillation. Basal levels were compared with those found in plasma of 20 healthy subjects matched by sex and age. Transthoracic echocardiography was made.

RESULTS

A significant increase for PAI-1 and D-dimer levels were detected in patients with atrial fibrillation group (p < 0.05), with no differences in tPA and PAP concentrations. Significant correlation between left atrial diameter and basal t-PA levels was found. Levels of t-PA, PAI-1 and D-dimer decreased significantly under anticoagulation therapy, whereas PAP levels were significantly increased.

CONCLUSIONS

Patients with rheumatic atrial fibrillation show a relative hypofibrinolytic state due to elevated PAI-1 levels with no increase in PAP concentration. At six months of anticoagulation therapy, an improvement of fibrinolytic function markers was observed. This is consistent with the prophylactic effect of oral anticoagulants therapy against thromboembolic risk.

Hypofibrinolysis in atrial fibrillation

BACKGROUND

There is a high incidence of systemic embolism in patients with chronic atrial fibrillation. A hypercoagulable state has been demonstrated, but the fibrinolytic system is rarely studied.

METHODS

Plasma levels of modified antithrombin III (ATM), tissue plasminogen activator (TPA), its inhibitor (PAI-1), TPA-PAI-1 complexes and plasmin-antiplasmin complexes (PAP), d -dimer, and fibrinogen were measured in plasma from 36 patients with chronic atrial fibrillation. Fifteen patients had rheumatic mitral stenosis and 21 had nonrheumatic atrial fibrillation. Levels were compared with those found in the plasma of 20 healthy subjects. Transthoracic echocardiographic studies were done.

RESULTS

Patients with atrial fibrillation had higher plasma levels of ATM, d -dimer, PAI-1, and TPA-PAI-1 complexes than controls (P <.001). The rheumatic atrial fibrillation group also showed elevated levels of fibrinogen (P <. 05). No significant differences were found in TPA and PAP. There were no differences between rheumatic and nonrheumatic atrial fibrillation.

CONCLUSIONS

Atrial fibrillation shows a hypofibrinolytic state caused by elevated PAI-1 levels with no increase in PAP complex concentration. Elevated plasma d -dimer levels suggest increased intravascular thrombogenesis. This may contribute to increased risk of thrombosis.

Effect of warfarin on regional left atrial coagulation activity in mitral stenosis

Increased regional left atrial (LA) coagulation activity has recently been implicated in the pathophysiology of LA thrombus and systemic embolism in mitral stenosis (MS). Anticoagulation with warfarin reduces the risk of such thromboembolism, but the effect of warfarin on LA coagulation activity is unknown. We have addressed this question in MS patients with normal or prolonged clotting times. Peripheral venous and LA coagulation activities were measured in MS patients on long-term oral anticoagulation, who were predisposed to increased LA coagulation activity because of the presence of LA spontaneous echo contrast. Patients ceased warfarin 4 days before percutaneous balloon mitral valvuloplasty, and had either a normal (n = 15) or prolonged (n = 8) International Normalized Ratio (INR) at valvuloplasty. Coagulation activity was assessed during the valvuloplasty procedure, but before valve dilation, by measuring levels of prothrombin fragment 1 + 2 (F1 + 2), a marker of thrombin generation. The LA F1 + 2 level exceeded the peripheral venous level in patients with a normal INR (p <0.001), but these levels were similar in patients with a prolonged INR (p = 0.16). Moreover, the LA (p <0.005) and peripheral venous (p <0.03) F1 + 2 levels, as well as the LA-peripheral venous F1 + 2 difference (p <0.03) were lower in patients with a prolonged INR. These results suggest that anticoagulation with warfarin in MS not only reduces systemic coagulation activity but is associated with a greater reduction in LA coagulation activity. The latter may contribute to the reduced risk of LA thrombus formation that accompanies warfarin therapy in MS.

Hypercoagulable state under low-intensity warfarin anticoagulation assessed with hemostatic markers in cardiac disorders

The hemostatic condition under low-intensity anticoagulation in cardiac disorders is not fully elucidated. The aim of this study was to ascertain whether hemostatic molecular markers are a useful assessment for anticoagulation to detect the hypercoagulable state. A hematologic study was performed in 75 outpatients, without thromboembolic episodes, treated with low-intensity anticoagulation (average international normalized ratio [INR] 1.72) because of potential cardiac sources of arterial emboli, and in 40 age-matched control subjects. The average level of thrombin-antithrombin III complex (TAT) was significantly lower in patients than in control subjects (p = 0.005), and the mean value of D-dimer was not statistically different between patients and control subjects. Although TAT correlated moderately with D-dimer (r = 0.45, p = 0.0001), INR did not correlate with TAT or D-dimer. Elevated TAT > 3.0 ng/ml and/or D-dimer S 150 ng/ml were observed in 15 patients (20.0%), whereas the remaining 60 patients (80.0%) had no obvious increase in the level of TAT or D-dimer at overall INR. Antithrombin III activity did not correlate significantly with INR, but protein C activity and free protein S antigen showed a significant negative relation to INR (r = 0.82, r = 0.62, respectively, p = 0.0001). Low-intensity anticoagulation was sufficient to reduce coagulation and subsequent fibrinolytic activation in cardiac disorders, but may not be sufficient in some patients with elevated TAT or D-dimer concentration.(ABSTRACT TRUNCATED AT 250 WORDS)