European Atrial Fibrillation Trial Study Group. Optimal oral anticoagulant therapy in patients with nonrheumatic atrial fibrillation and recent cerebral ischemia

Anticoagulation for Atrial Fibrillation: A Review of Current Literature and Views

Atrial fibrillation is a common supraventricular tachyarrhythmia with uncoordinated atrial activation and ineffective atrial contraction. This leads to an increased risk of atrial thrombi, most commonly in the left atrial appendage, and increased risks of embolic strokes and/or peripheral thromboembolism. It is associated with significant morbidity and mortality. To meet the concerns of thrombi and stroke, anticoagulation has been the mainstay for prevention and treatment thereof. Historically, anticoagulation involved the use of aspirin or vitamin K antagonists, mainly warfarin. Since early 2010s, direct oral anticoagulants (DOACs) including dabigatran, rivaroxaban, apixaban, and edoxaban have been introduced and approved for anticoagulation of atrial fibrillation. DOACs demonstrated a dramatic reduction in the rate of intracranial hemorrhage as compared to warfarin, and offer the advantages of absolution of monitoring therefore avoid the risk of hemorrhages in the context of narrow therapeutic window and under-treatment characteristic of warfarin, particularly in high-risk patients. One major concern and disadvantage for DOACs was lack of reversal agents, which have largely been ameliorated by the approval of Idarucizumab for dabigatran and Andexanet alfa for both apixaban and rivaroxaban, with Ciraparantag as a universal reversal agent for all DOACs undergoing Fast-Track Review from FDA. In this article, we will be providing a broad review of anticoagulation for atrial fibrillation with a focus on risk stratification schemes and anticoagulation agents (warfarin, aspirin, DOACs) including special clinical considerations.

Net clinical benefit of oral anticoagulants in Asian patients with atrial fibrillation based on a CHA2DS2-VASc score

BACKGROUND

This study was conducted to assess the net clinical benefit (NCB) for oral anticoagulant (OAC) in atrial fibrillation (AF) patients according to the CHA2DS2-VASc score.

METHODS

Patients with AF were prospectively recruited in the COOL AF Thailand registry from 2014 to 2017. The incidence rate of thromboembolic (TE) events and major bleeding (MB) was calculated. Cox proportional hazards model was used to compare the TE and MB rate in patients with and without OACs in CHA2DS2-VASc score of 0-1 and ≥ 2, respectively. The survival analysis was performed based on CHA2DS2-VASc score. The NCB of OACs was defined as the TE rate prevented minus the MB rate increased multiplied by a weighting factor.

RESULTS

A total of 3,402 AF patients were recruited. An average age of patients was 67.38 ± 11.27 years. Compared to non-anticoagulated patients, the Kaplan Meier curve showed anticoagulated patients with CHA2DS2-VASc score of 2 or more had the lower thromboembolic events with statistical significance (p = 0.043) and the higher MB events with statistical significance (p = 0.018). In overall AF patients, there were positive NCB in warfarin patients with CHA2DS2-VASc score of 3 or more while there were positive NCB in DOACs patients regardless of CHA2DS2-VASc score. Females with CHA2DS2-VASc score of 3 or more had a positive NCB regardless of OACs type. Good anticoagulation control (TTR ≥65%) improved an NCB in males with CHA2DS2-VASc score of 3 or more.

CONCLUSIONS

AF patients with CHA2DS2-VASc score of 3 or more regardless warfarin or DOACs had a positive NCB. The NCB of OACs was more positive for DOACs compared to warfarin and for females compared to males.

Spontaneous Iliopsoas Hematoma in a Patient on Acenocoumarol: Report of a Rare Case

Spontaneous hematoma of the iliopsoas is a rare pathological circumstance; in the majority of cases published in the literature, it is associated with disorders of hemostasis due to anticoagulant treatment or coagulopathies. We present a case of a 64-year-old man on acenocoumarol, an anticoagulant of the vitamin K antagonist family, for atrial fibrillation, who presented with a severe left hip and flank pain with a huge ecchymosis on the left flank and a partial inability to extend the left thigh. A CT scan confirmed the diagnosis of iliopsoas hematoma. Given the hemodynamic stability of the patient, he benefited from a conservative treatment with a favourable evolution. This case highlights the underlying conditions, diagnosis, and treatment of this uncommon complication.

Left Atrial Appendage Thrombosis and Oral Anticoagulants: A Meta-Analysis of Risk and Treatment Response

Background: Left atrial appendage thrombus (LAAT) is the main cause of cardioembolism in patients with nonvalvular atrial fibrillation (AF). Emerging evidence indicates that direct oral anticoagulants (DOACs) may be a preferred, safer choice for patients with LAAT. However, current guidelines indicate vitamin K antagonist (VKA) as the preferred treatment for LAAT. We conducted a meta-analysis to compare the efficacy of VKA and DOAC for the treatment of LAAT. Methods: The search was conducted in the PubMed, Embase, Google Scholar, and Cochrane Library databases from inception to July 2022, with the language restricted to English. A first analysis was conducted to evaluate the risk of LAAT under VKA or DOAC treatment. A second analysis was conducted to compare the resolution of LAAT under VKA and DOAC treatment. Results: In 13 studies comparing LAAT incidence rates under VKA and DOAC treatment, significant superiority of DOAC was detected (pooled RR = 0.65, 95% CI = 0.47-0.90, p = 0.009) with moderate heterogeneity being identified in the pooled studies. In 13 studies comparing LAAT resolution under VKA and DOAC use, treatment with DOAC exhibited a significantly increased probability of LAAT resolution compared with VKA (pooled odds ratio = 1.52, 95% CI = 1.02-2.26, p = 0.040). Conclusions: This meta-analysis suggests a superiority of DOAC over VKA with respect to LAAT incidence in people with AF and the likelihood of LAAT resolution. Due to their established safety profile, DOAC is a preferable choice for anticoagulation, although further randomized controlled studies are warranted to provide further evidence of their suitability as a new recommended treatment.

The impact of acute diarrhea on the coagulation status of patients with vitamin K antagonists

Acute diarrhea is associated with a reduced absorption of both vitamin K antagonists (VKA) and vitamin K itself. To date, the net effect on the coagulation status of subjects with VKA remains elusive. We performed a systematic retrospective single-center analysis using an electronic data extraction approach to identify subjects with plasmatic anticoagulation (either VKA or direct oral anticoagulant (DOAC)) and diarrhea in a German University Hospital over a period of eight years. Acute diarrhea and complete documentation of coagulation status on admission were defined as inclusion criteria, anticoagulation other than VKA/DOAC and obvious inadherence as exclusion criteria. Subjects with VKA/DOAC admitted for hypertension served as control group. Data extraction yielded 356 subjects with gastrointestinal diagnoses and 198 hypertensive subjects, 55 and 83 of whom fulfilled all in- and exclusion criteria. INR values of subjects with VKA were significantly higher in subjects with diarrhea than in hypertensive controls (4.3 ± 3.7 vs. 2.3 ± 0.7, p < 0.001). The distribution of subjects having INR values lower, higher or within the target range differed significantly among groups with a substantially higher prevalence of overanticoagulation in the diarrhea group (46.4% vs. 14.3%, p < 0.001). In a multinomial logistic regression model, acute diarrhea was significantly associated with overanticoagulation (odds ratio 7.2, 95% confidence interval 2.163–23.921; p < 0.001), whereas age, sex, creatinine, and indication of anticoagulation were not (p > 0.05 each). Acute diarrhea is associated with a highly increased risk for overanticoagulation in patients with VKA. Thus, gastroenteritis necessitates a close monitoring of INR in order to identify subjects needing a temporary pause of VKA therapy.

Association between Patients' Knowledge and Adherence to Anticoagulants, and Its Effect on Coagulation Control

BACKGROUND

Warfarin requires strict monitoring by measuring prothrombin time (PT), international normalized ratio (INR), and time in therapeutic range (TTR). Several factors can lead to poor PT/INR control including vitamin K status, medication adherence, knowledge, and quality of life. The present study aims to assess patient adherence to warfarin treatment and its correlation with INR control.

METHODS

A cross-sectional study was conducted between October 2017 and January 2018 at Tripoli University Hospital. Data were collected by structured questionnaires which included; demographic and clinical characteristics, the Oral Anticoagulation Knowledge (OAK) test, and the Morisky Medication Adherence Scale (MMAS-8).

RESULTS

The final analysis included 88 out of 140 patients (73.33%). There were significant differences in age range, gender, marital status, and education level between the 2 groups (poor knowledge and adequate knowledge) (p < 0.05). There was a significant positive correlation between OAK test score and TTR. Overall, 76.2% of patients were adherent to warfarin (MMAS score ≥6) and 20.45% of patients were of high adherence (MMAS score of 8). The median score was 6 (IQR 6-7). A statistically significant, strong positive correlation between adherence to medication and TTR as an indicator of INR control was found (rs[86] = 0.472, p < 0.0001).

CONCLUSION

The study addressed and identified several areas for future improvement of patient outcomes. The implementation of new approaches to enhance patient knowledge and adherence is warranted, and measures to provide treatment for all patients that require it are needed, to improve outcomes and decrease adverse drug effects.

Anticoagulation control in different ethnic groups receiving vitamin K antagonist therapy for stroke prevention in atrial fibrillation

BACKGROUND

Efficacy and safety of vitamin K antagonists (VKAs) is optimised in atrial fibrillation (AF) patients when the International Normalised Ratio (INR) is 2.0-3.0. Anticoagulation control comparing different ethnic groups is limited, although epidemiological studies suggest poorer INR control in non-white cohorts.

METHODS

VKA control was assessed retrospectively by time-in-the-therapeutic range (TTR) (Rosendaal method) and percentage INR-in-range (PINRR) in 991 White, Afro-Caribbean and South-Asian AF patients [overall mean (SD) age 71.6 (9.4) years; 55% male; mean (SD) CHA₂DS₂-VASc score 3.4 (1.6)] over a median (IQR) follow-up of 5.2 (3.2-7.0) years.

RESULTS

Compared to Whites, mean (SD) TTR and PINRR were significantly lower in South-Asians [TTR 67.9% vs. 60.5%; PINRR 58.8% vs. 51.6%, respectively] and Afro-Caribbeans [TTR 67.9% vs. 61.3%; PINRR 58.8% vs. 53.1%, respectively], despite similar INR monitoring intensity. Logistic regression revealed non-white ethnicity [OR 2.62; 95% Confidence Interval [CI] (1.67-4.10) and OR 3.47 (1.44-8.34)] and anaemia [OR 1.65 (1.00-2.70) and OR 6.27 (1.89-20.94)] as independent predictors of both TTR and PINRR < 70%, respectively. At follow-up, 329 (33.2%) patients experienced ≥1 major adverse clinical event. Cardiovascular hospitalisation was significantly higher among South-Asians (32.3%) compared to the Whites and Afro-Caribbeans (21.3% vs 25.6% respectively).

CONCLUSIONS

Ethnic disparities in quality of anticoagulation control are evident, with South-Asians and Afro-Caribbeans having poorer control compared to Whites, despite similar intensity INR monitoring. Non-white ethnicity remained the strongest independent predictor of poor TTR and PINRR. Interventions to improve anticoagulation control need to be implemented, particularly targeting ethnic minority patients.

Management of Direct Oral Anticoagulants in Patients with Atrial Fibrillation Undergoing Cardioversion

Atrial fibrillation the most common cardiac arrhythmia. Its incidence rises steadily with each decade, becoming a real “epidemic phenomenon”. Cardioversion is defined as a rhythm control strategy which, if successful, restores normal sinus rhythm. This, whether obtained with synchronized shock or with drugs, involves a periprocedural risk of stroke and systemic embolism which is reduced by adequate anticoagulant therapy in the weeks before or by the exclusion of left atrial thrombi. Direct oral anticoagulants are safe, manageable, and provide rapid onset of oral anticoagulation; they are an important alternative to heparin/warfarin from all points of view, with a considerable reduction in bleedings and increase in the safety and quality of life of patients.

Impact of Anticoagulation Intensity in Korean Patients with Atrial Fibrillation: Is It Different from Western Population?

BACKGROUND AND OBJECTIVES

Although anticoagulation with warfarin is recommended as an international normalized ratio (INR) of prothrombin time between 2.0 and 3.0 and mean time in the therapeutic range (TTR) ≥70%, little has been proven that universal criteria might be suitable in Korean atrial fibrillation (AF) patients.

METHODS

We analyzed 710 patients with non-valvular AF who took warfarin. INR value and clinical outcomes were assessed during 2-year follow-up. Intensity of anticoagulation was assessed as mean INR value and TTR according to target INR range. Primary net-clinical outcome was defined as the composite of new-onset stroke and major bleeding. Secondary net-clinical outcome was defined as the composite of new-onset stroke, major bleeding and death.

RESULTS

Thromboembolism was significantly decreased when mean INR was over 1.6. Major bleeding was significantly decreased when TTR was over 70% and mean INR was less than 2.6. Mean INR 1.6-2.6 significantly reduced thromboembolism (adjusted hazard ratio [HR], 0.40; 95% confidence interval [CI], 0.19-0.85), major bleeding (HR, 0.43; 95% CI, 0.23-0.81), primary (HR, 0.50; 95% CI, 0.29-0.84) and secondary (HR, 0.45; 95% CI, 0.28-0.74) net-clinical outcomes, whereas mean INR 2.0-3.0 did not. Simultaneous satisfaction of mean INR 1.6-2.6 and TTR ≥70% was associated with significant risk reduction of major bleeding, primary and secondary net-clinical outcomes.

CONCLUSIONS

Mean INR 1.6-2.6 was better than mean INR 2.0-3.0 for the prevention of thromboembolism and major bleeding. However, INR 1.6-2.6 and TTR ≥70% had similar clinical outcomes to INR 2.0-3.0 and TTR ≥70% in Korean patients with non-valvular AF.

Efficacy of Direct Acting Oral Anticoagulant Drugs in Treatment of Left Atrial Appendage Thrombus in Patients With Atrial Fibrillation

Direct acting oral anticoagulants (DOACs) are increasingly used for thromboembolic prophylaxis in patients with atrial fibrillation (AF). However, there is limited data to evaluate the use of DOACs for the treatment of pre-existing left atrial appendage thrombus. We aimed to determine the efficacy of DOACs in treatment of left atrial appendage (LAA) thrombus utilizing transesophageal echocardiographic (TEE) and clinical outcomes. In this single-center study, we identified 33 patients that were treated for LAA thrombus with DOAC. Eighteen were treated with apixaban, 10 with dabigatran, and 5 with rivaroxaban. The primary endpoint was defined as resolution of LAA thrombus (in patients undergoing TEE), or death, major bleeding requiring transfusion, intracranial hemorrhage, ischemic stroke, or peripheral embolization. In this study, 15 of the 16 patients treated with DOACs who underwent follow-up TEE had resolution of LAA thrombus, with a mean duration of 112 days. Of the 15 patients who achieved resolution of the LAA thrombus, 14 had resolution by their first follow-up TEE. In the 17 patients without a follow-up TEE, 1 died of a retroperitoneal bleed (28 days after DOAC initiation), and 1 suffered an ischemic stroke (484 days after DOAC initiation). In general, patients without a follow-up TEE were older and had more co-morbidities. Although these results are descriptive and limited in number of patients, we believe this is ample evidence that DOACs are relatively safe and efficacious in treatment of patients with AF and concomitant LAA thrombus.

Rapid and substantial increases in anticoagulant use and expenditure in Australia following the introduction of new types of oral anticoagulants

Objectives

To quantify changes in anticoagulant use in Australia since the introduction of Non-vitamin K antagonist anticoagulants (NOACs) and to estimate government expenditure.

Design

Interrupted-time-series analysis quantifying anticoagulant dispensing, before and after first Pharmaceutical Benefits Scheme (PBS) NOAC listing in August 2009 for venous thromboembolism prevention; and expanded listing for stroke prevention in non-valvular atrial fibrillation (AF) in August 2013, up to June 2016. Estimated government expenditure on PBS-listed anticoagulants.

Setting and participants

PBS dispensing in 10% random sample of Australians, restricted to continuous concessional beneficiaries dispensed oral anticoagulants from July 2005 to June 2016. Total PBS anticoagulant expenditure was calculated using Medicare Australia statistics.

Main outcome measures

Monthly dispensing and initiation of oral anticoagulants (warfarin, rivaroxaban, dabigatran or apixaban). Annual PBS anticoagulant expenditure.

Results

An estimated 149,180 concessional beneficiaries were dispensed anticoagulants (100% warfarin) during July 2005. This increased to 292,550 during June 2016, of whom 47.0%, 27.1%, 18.7% and 7.2% were dispensed warfarin, rivaroxaban, apixaban and dabigatran, respectively. Of 16,500 initiated on anticoagulants in June 2016, 24.3%, 38.2%, 30.0% and 7.5% were initiated on warfarin, rivaroxaban, apixaban, and dabigatran, respectively. Compared to July 2005-July 2013, from August 2013-June 2016, dispensings for all anticoagulants increased by 2,303 dispensings/month (p<0.001, 95%CI = [1,229 3,376]); warfarin dispensing decreased by 1,803 dispensings/month (p<0.001, 95%CI = [–2,606, –1,000]). Total PBS anticoagulant expenditure was $19.5 million (97.0% concessional) in 2008/09, of which 100% was warfarin and $203.3 million (86.2% concessional) in 2015/16, of which 11.2% was warfarin.

Conclusions

The introduction of the NOACs led to substantial increases in anticoagulant use and expenditure in Australia.

Level of agreement between laboratory and point-of-care prothrombin time in patients after stopping or continuation of acenocoumarol anticoagulation: A comparison of diagnostic accuracy

BACKGROUND

Procedures requiring optimisation of the coagulation status of patients using vitamin K antagonists are frequently postponed due to the late availability of laboratory international normalised ratio (INR) test results. A point-of-care (POC) alternative may facilitate early decision-making in peri-operative patients.

OBJECTIVES

To assess the level of agreement between the POC-INR and the laboratory INR in patients who continue or stop vitamin K antagonists to determine whether the POC test may be a good alternative to the laboratory INR.

DESIGN

Study of diagnostic accuracy.

SETTING

Single-centre study at Zaans Medical Centre, The Netherlands.

PATIENTS

Included patients were scheduled for cardioversion (these continued taking vitamin K antagonists), or a surgical procedure (these stopped taking vitamin K antagonists).

MAIN OUTCOME MEASURES

The level of agreement and clinical acceptability of the laboratory and POC-INR results, evaluated by Bland-Altman analysis and error grid analysis.

RESULTS

The surgical and cardioversion groups consisted of 47 and 46 patients, respectively. The bias in the INR in the surgical group was -0.12 ± 0.09 with limits of agreement of -0.29 to 0.05, whereas the cardioversion group showed a bias in the INR of -0.22 ± 0.36 with limits of agreement from -0.93 to 0.48. The percentage errors between methods in the surgical and cardioversion groups were 16 and 21%, respectively. Error grid analysis showed that the diagnostic accuracy of the POC prothrombin time is clinically acceptable as the difference did not lead to a different clinical decision in the surgical group with INR values less than 1.8.

CONCLUSION

The current study shows a good level of agreement and clinical accuracy between the laboratory and POC-INR in patients who stopped anticoagulation intake for surgery. However, in patients who continued their anticoagulation therapy, the agreement between the two methods was less accurate.

Bleeding and asymptomatic overdose in patients under Vitamin K antagonist therapy: Frequency and risk factors

Background

Vitamin K antagonists are widely used in the treatment and prevention of thromboembolic disease. However, these drugs can cause serious side effects, especially bleeding. This study aims to evaluate frequency and risk factors of both bleeding and asymptomatic overdose in North African patients undergoing Vitamin K antagonist therapy.

Methods

We performed a cross-sectional study in patients undergoing Vitamin K antagonist therapy. A statistical analysis has been conducted to identify overdose and bleeding risk factors by using chi-square test (p < .05).

Results

One hundred and eleven patients were included. We recorded 14 cases of bleeding and 26 cases of asymptomatic overdose. Advanced age, poor adherence, concomitant use of paracetamol and history of previous bleeding are significant risk factors of over-anticoagulation. An INR value over 6 at admission, a high therapeutic target range for INR, concomitant use of acetylsalicylic acid, lack of information on overdose signs and measures to be taken in case of bleeding were identified as risk factors for bleeding.

Conclusion

Most of the risk factors identified in our study seem to be related to patients lack of information and education. These results highlight the importance of creating a therapeutic patient education program.

Resolution of Left Atrial Appendage Thrombus with Apixaban in a Patient with Heart Failure

The effect of non-vitamin K antagonist oral anticoagulants on left atrial appendage (LAA) thrombus has not been fully elucidated. There are a few reports showing resolution of LAA thrombus with apixaban. An 84-year-old woman was admitted to our hospital due to acute exacerbation of chronic heart failure and marked tachycardia with atrial fibrillation. She had permanent atrial fibrillation and was treated with warfarin; however, transthoracic echocardiography revealed a non-mobile thrombus in the LAA. Therefore, we switched warfarin to apixaban at a dose of 5 mg/day. After two weeks on that therapy, the thrombus in the LAA was successfully resolved.

Bleeding risk of endoscopic ultrasound-guided fine-needle aspiration in patients undergoing antithrombotic therapy

OBJECTIVES

Bleeding events related to endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) are rare. However, for patients treated with antithrombotic agents, the bleeding risk of EUS-FNA is uncertain. Hence, the aim of this study was to assess the bleeding event rate associated with EUS-FNA in patients receiving antithrombotic treatment.

METHODS

A retrospective study was conducted in 742 consecutive patients who underwent EUS-FNA for solid lesions between 2008 and 2015. We compared the bleeding event rates among patients who were not administered antithrombotic agents, those whose agent use was discontinued, those who continued treatment with aspirin or cilostazol, and those who were administered heparin as a replacement.

RESULTS

There were 131 patients (17.7 %) treated with antithrombotic agents. Seven experienced bleeding events, and the overall bleeding event rate was 0.9 % (7/742). All bleeding events were intraoperative; there were no postoperative bleeding episodes. Subgroup analysis by antithrombotic agent revealed bleeding event rates of 1.0 % (6/611), 0 % (0/62), 1.6 % (1/61), and 0 % (0/8) for the non-administration, discontinuation of agents, continuation of aspirin or cilostazol, and heparin replacement groups, respectively. Only one severe bleeding event necessitated hemostatic treatment (1/742; 0.1 %); this occurred in a patient in the non-administration group, and there were no severe bleeding events in patients receiving antithrombotic treatment.

CONCLUSIONS

The present study found a low incidence of EUS-FNA-related bleeding in patients receiving antithrombotic treatment. The bleeding event rate was low even in patients who underwent EUS-FNA while continuing aspirin or cilostazol.

Advances in anticoagulation management of patients undergoing cardioversion of nonvalvular atrial fibrillation

Atrial fibrillation (AF) is a major cause of stroke. The restoration of sinus rhythm through cardioversion, either chemical or electrical is a common practice. Interestingly, there is an incremental increase from the baseline risk for embolisation in the immediate post-cardioversion period, with most events occurring within 10 days from cardioversion. Especially patients with recent onset AF show the lowest rates of antithrombotic therapy, while having a high stroke risk. Despite the increased risk for embolisation, anticoagulation in patients undergoing cardioversion of atrial fibrillation is often inadequate. Moreover, since the implementation of non-vitamin K antagonists oral anticoagulants (DOACs) there are several therapeutic approaches for pericardioversion anticoagulant therapy and not all suits to all patients. In addition, the extensive use of transesophageal echocardiography provides an alternative strategy, especially useful for patients of high haemorrhagic risk. In this review article, we aim to provide an update on the anticoagulation strategies for patients undergoing cardioversion of non-valvular atrial fibrillation in the advent of the use of DOACs.

An expanded pharmacogenomics warfarin dosing table with utility in generalised dosing guidance

Pharmacogenomics (PGx) guided warfarin dosing, using a comprehensive dosing algorithm, is expected to improve dose optimisation and lower the risk of adverse drug reactions. As a complementary tool, a simple genotype-dosing table, such as in the US Food and Drug Administration (FDA) Coumadin drug label, may be utilised for general risk assessment of likely over- or under-anticoagulation on a standard dose of warfarin. This tool may be used as part of the clinical decision support for the interpretation of genetic data, serving as a first step in the anticoagulation therapy decision making process. Here we used a publicly available warfarin dosing calculator (www.warfarindosing.org) to create an expanded gene-based warfarin dosing table, the CPMC-WD table that includes nine genetic variants in CYP2C9, VKORC1, and CYP4F2. Using two datasets, a European American cohort (EUA, n=73) and the Quebec Warfarin Cohort (QWC, n=769), we show that the CPMC-WD table more accurately predicts therapeutic dose than the FDA table (51 % vs 33 %, respectively, in the EUA, McNemar's two-sided p=0.02; 52 % vs 37 % in the QWC, p<1×10(-6)). It also outperforms both the standard of care 5 mg/day dosing (51 % vs 34 % in the EUA, p=0.04; 52 % vs 31 % in the QWC, p<1×10(-6)) as well as a clinical-only algorithm (51 % vs 38 % in the EUA, trend p=0.11; 52 % vs 45 % in the QWC, p=0.003). This table offers a valuable update to the PGx dosing guideline in the drug label.

Evaluation of a Potential Interaction Between New Regimens to Treat Hepatitis C and Warfarin

OBJECTIVE

New regimens to treat hepatitis C virus infection have expanded the eligible patient population to include more patients receiving concurrent warfarin. The primary objective of this study was to assess whether a drug interaction occurs when these regimens are added to warfarin therapy.

METHODS

This was a retrospective cohort design using a nationwide database of the Veterans Affairs Health System. Patients on warfarin therapy treated with sofosbuvir or ombitasvir, paritaprevir-ritonavir, and dasabuvir (OBV-PTV/r-DSV) from March 2014 through October 2015 were identified. The warfarin dose response was calculated using a warfarin sensitivity index (WSI) defined as the steady-state INR divided by the mean daily warfarin dose. The primary outcome was the change in WSI from hepatitis C treatment initiation to completion.

RESULTS

The final sample consisted of 271 patients. The WSI decreased 23% from a mean baseline value of 0.53 to 0.39 (decrease of 0.14; 95% CI = 0.11 to 0.16; P < 0.001). OBV-PTV/r-DSV produced a significantly greater decrease than any sofosbuvir regimen. Concurrent ribavirin accounted for an additional decrease in warfarin sensitivity of -0.09 (95% CI = -0.06 to -0.12; P < 0.001). The percentage of subtherapeutic INR results increased from 26% prior to hepatitis C treatment to 58% during treatment.

CONCLUSIONS

Results indicate a clinically significant reduction in warfarin dose-response when hepatitis C treatment regimens were added to warfarin. They were most profound with OBV-PTV/r-DSV. Ribavirin was associated with an additive effect. Clinicians should be aware of this potential drug interaction to closely monitor and minimize subtherapeutic levels of anticoagulation.

Ezetimibe enhances and stabilizes anticoagulant effect of warfarin

Ezetimibe reduces plasma levels of low-density lipoprotein cholesterol by inhibiting Niemann-Pick C1-like protein 1 (NPC1L1). A recent study demonstrated that NPC1L1 plays an important role in absorption of fat-soluble vitamins including vitamin K. We evaluated whether the add-on treatment of ezetimibe affects anticoagulation in patients taking warfarin. Between October 2007 and March 2015, the administration of ezetimibe was started to a total of 101 outpatients who were already on oral anticoagulation with warfarin. We retrospectively analyzed blood lipid levels, prothrombin time international normalized ratio (PT-INR) and time in therapeutic INR range (TTR). Seventy-one patients (70 %) showed increase in PT-INR after ezetimibe treatment (1.96 ± 0.45 to 2.20 ± 0.61, p < 0.001). It was necessary to reduce the warfarin dose in 9 of 101 patients for clinical indication. There was a significant positive correlation between change in PT-INR and statin usage at baseline (p = 0.03). The mean value of changes in PT-INR of patients with taking statin was significantly larger than that of patients without taking statin (0.34 ± 0.54 vs. 0.06 ± 0.36, p = 0.03). There was an increase in the TTR (52 ± 26 to 61 ± 23 %, p < 0.0001) and a decrease in the frequency to change the dose of warfarin after the ezetimibe treatment [45 times of 735 examination days (6 %) to 20 times of 695 examination days (3 %), p = 0.02]. Our data suggest possible drug interaction between warfarin and ezetimibe. Ezetimibe may increase and stabilize the anticoagulant effect of warfarin, especially in patients taking statins.

Impact of GGCX, STX1B and FPGS Polymorphisms on Warfarin Dose Requirements in European-Americans and Egyptians

Genotype-based algorithms that include VKORC1 and CYP2C9 genotypes are less predictive of warfarin dose variability in Africans as opposed to Europeans. Polymorphisms in GGCX, FPGS, or STX1B are associated with warfarin dose requirements in African-Americans. We sought to determine if they influenced warfarin dose in European-Americans, and another African population, specifically Egyptians. We genotyped 529 adults (n = 325 European-Americans, 204 Egyptians) on a stable warfarin dose for GGCX rs12714145 and rs10654848, FPGS rs7856096, and STX1B rs4889606. Rs12714145, rs10654848, and rs7856096 were not associated with warfarin dose, whereas STX1B rs4889606 was a significant determinant in univariate analysis (P < 0.0001) in both cohorts. However, STX1B rs4889606 was in high linkage disequilibrium with VKORC1-1639 G>A, and was no longer significant after including VKORC1-1639 G>A in the regression model. Based on these data, the polymorphisms do not appear to influence, in a clinically important way, warfarin dose requirements in European-Americans and Egyptians.

Aspirin Compared to Low Intensity Anticoagulation in Patients with Non-Valvular Atrial Fibrillation. A Systematic Review and Meta-Analysis

Background

Despite its lack of efficacy, aspirin is commonly used for stroke prevention in atrial fibrillation. Since prior studies have suggested a benefit of low-intensity anticoagulation over aspirin in the prevention of vascular events, the aim of this systematic review was to compare the outcomes of patients with non-valvular atrial fibrillation treated with low-intensity anticoagulation with Vitamin K antagonists or aspirin.

Methods

We conducted a systematic review searching Ovid MEDLINE, Embase and the Cochrane Central Register of Controlled Trials, from 1946 to October 14^th, 2015. Randomized controlled trials were included if they reported the outcomes of patients with non-valvular atrial fibrillation treated with a low-intensity anticoagulation compared to patients treated with aspirin. The primary outcome was a combination of ischemic stroke or systemic embolism. The random-effects model odds ratio was used as the outcome measure.

Results

Our initial search identified 6309relevant articles of which three satisfied our inclusion criteria and were included. Compared to low-intensity anticoagulation, aspirin alone did not reduce the incidence of ischemic stroke or systemic embolism OR 0.94 (95% CI 0.57–1.56), major bleeding OR 1.06 (95% CI 0.42–2.62) or vascular death OR 1.04 (95% CI 0.61–1.75). The use of aspirin was associated with a significant increase in all-cause mortality OR 1.66 (95% CI 1.12–2.48).

Conclusion

In patients with non-valvular atrial fibrillation, aspirin provides no benefits over low-intensity anticoagulation. Furthermore, the use of aspirin appears to be associated with an increased risk in all-cause mortality. Our study provides more evidence against the use aspirin in patients with non-valvular atrial fibrillation.

The role of soluble fibrin during anticoagulant therapy: a case report

Warfarin, dabigatran, and apixaban are used for preventing ischemic stroke due to non-valvular atrial fibrillation (NVAF). However, it is often challenging to select the appropriate anticoagulant. We present the case of a 70-year-old male patient with persistent NVAF who developed pulmonary thromboembolism (PTE), deep vein thrombosis (DVT), and left atrial thrombus during anticoagulant therapy with warfarin. Intravenous recombinant tissue plasminogen activator was administered during his acute PTE. Heparin and apixaban were administered over 28 days; heparin was discontinued after the DVT resolved, while apixaban was administered to prevent ischemic stroke. Two days after heparin was discontinued, the patient experienced an ischemic stroke. Dabigatran was administered for secondary ischemic stroke prevention. Soluble fibrin (SF) levels remained elevated during treatment with heparin and apixaban and returned to normal after apixaban was replaced with dabigatran. Monitoring of SF may be useful as an index for selection of anticoagulants.

Cardioversion of uncomplicated paroxysmal atrial fibrillation: a survey of practice by Canadian emergency physicians

Objective:

Paroxysmal atrial fibrillation (PAF) is the rhythm disturbance most commonly encountered by emergency physicians, yet the role played by emergency physicians in the management of this condition has not been well described. The purpose of this study was to describe the management of uncomplicated PAF by Canadian emergency physicians.

Methods:

All members of the Canadian Association of Emergency Physicians with a Canadian address (n = 1255) were mailed a 15-point questionnaire regarding training/certification, hospital demographics and practice patterns regarding the management of uncomplicated PAF. Chisquared analysis and Fisher’s Exact test were performed to identify significant differences in reported practice patterns in relation to demographic variables. Significant associations were tested for interaction using the Mantel–Haenszel test.

Results:

We received 663 responses, representing a 52.8% response rate. Six hundred and twenty-two (95%), 514 (78%) and 242 (38%) respondents reported routine performance of rate control, chemical cardioversion and electrical cardioversion respectively. Physicians working in high-volume emergency departments (&gt;50 000 visits/yr) were significantly more likely to self-manage rate control and chemical/electrical cardioversion than those working in lower volume emergency departments. Residency training was associated with higher performance of electrical (44% v. 31%, p &lt; 0.01) but not chemical cardioversion or rate control, although, amongst residency trained physicians, those with FRCP-level training were significantly more likely to perform both chemical (86% v. 76%, p &lt; 0.05) and electrical (57% v. 37%, p &lt; 0.01) cardioversion.

Conclusion:

Canadian emergency physicians surveyed in this study actively manage uncomplicated PAF. We found significant variations in practice, especially related to the use of electrical cardioversion. This may reflect different practice environments, levels of training, and lack of evidence to guide best practice. Further research is required to determine the optimal care of PAF in the emergency department setting.

The Optimal Treatment For Atrial Fibrillation In Less Developed Countries

Atrial fibrillation (AF) is the most common arrhythmia and is a major cardiovascular challenge due to its close association with increased morbidity and mortality. Although the incidence and prevalence of AF is slightly lower in developing countries than in developed countries, the AF-associated risk of stroke is similar. Treatment of AF is far from satisfactory in developing countries, which may be due to limited health-care resources and social and racial characteristics that differ from Western populations. Chronic rate control is still the main treatment strategy of persistent AF because anti-arrhythmic drugs have only a modest long-term effect on maintenance of sinus rhythm, and no superior impact in terms of cardiovascular outcomes. With the development of ablation techniques and strategies, more AF patients received catheter ablation, although the benefit, complications, and high recurrence rate associated with AF ablation remain under investigation. Improvement in antithrombotic therapy of AF has been observed, although still fewer patients receive oral anticoagulants in developing countries than in Western countries. Novel treatment for the prevention of thromboembolism, such as new oral anticoagulants with different mechanisms of action or the percutaneous transcatheter closure of the left atrial appendage, has recently been introduced in developing countries as an alternative option for the prevention of AF-associated strokes. More data are needed regarding upstream therapy.

Effect of impaired renal function on the maintenance dose of warfarin in Japanese patients

BACKGROUND

Chronic kidney disease (CKD) alters dose-effect relationship not only of drugs eliminated by the kidney but also of some drugs metabolized by the liver and not renally excreted. It is not known whether impaired renal function alters dose-effect relationship of warfarin in Asian patients. It is also unknown whether the maintenance dose of warfarin can be predicted more accurately by incorporating renal function in Asians.

METHODS

This was a cross-sectional study of patients receiving constant doses of warfarin who had PT-INR within 1.5-3.0 for 3 months or longer.

RESULTS

In a total of 137 participants, the estimated creatinine clearance (eCrCl) was 62.5±25.5 [ml/min] and the warfarin dose was 3.21±1.46 [mg/day] (both mean±standard deviation). There was a significant correlation between warfarin dose and eCrCl (p<0.0001, r(2)=0.23). In a stepwise linear regression with the maintenance dose of warfarin as the dependent variable, eCrCl as well as age, body weight, intra-individual average prothrombin time/international normalized ratio (PT-INR), and genotype of VKORC1 -1639 G>A polymorphism were chosen as independent variables. The coefficient of determination (r(2)) of this formula was 0.47. A regression equation with all the same explanatory variables except for eCrCl had an r(2) of 0.41.

CONCLUSIONS

The maintenance warfarin dose was positively correlated with kidney function as represented by eCrCl in Japanese patients. Incorporating eCrCl improved accuracy of predicting warfarin maintenance dose in this population.

Femoral Nerve Palsy due to Anticoagulant Induced Retroperitoneal Hematoma

A forty-one-year-old man who, sought evaluation for a sudden hip flexion contracture and groin pain with a history of mechanical mitral valve replacement, had been misdiagnosed and treated as having lumbar discopathy for two days. This patient finally was diagnosed with compressive femoral neuropathy due to warfarin-induced retroperitoneal hematoma and successfully managed nonoperatively. This case is reported in order to draw attention to this rare presentation.

Prospective randomized evaluation of the Watchman Left Atrial Appendage Closure device in patients with atrial fibrillation versus long-term warfarin therapy: the PREVAIL trial

BACKGROUND

In the PROTECT AF (Watchman Left Atrial Appendage Closure Technology for Embolic Protection in Patients With Atrial Fibrillation) trial that evaluated patients with nonvalvular atrial fibrillation (NVAF), left atrial appendage (LAA) occlusion was noninferior to warfarin for stroke prevention, but a periprocedural safety hazard was identified.

OBJECTIVES

The goal of this study was to assess the safety and efficacy of LAA occlusion for stroke prevention in patients with NVAF compared with long-term warfarin therapy.

METHODS

This randomized trial further assessed the efficacy and safety of the Watchman device. Patients with NVAF who had a CHADS2 (congestive heart failure, hypertension, age >75 years, diabetes mellitus, and previous stroke/transient ischemic attack) score ≥2 or 1 and another risk factor were eligible. Patients were randomly assigned (in a 2:1 ratio) to undergo LAA occlusion and subsequent discontinuation of warfarin (intervention group, n = 269) or receive chronic warfarin therapy (control group, n = 138). Two efficacy and 1 safety coprimary endpoints were assessed.

RESULTS

At 18 months, the rate of the first coprimary efficacy endpoint (composite of stroke, systemic embolism [SE], and cardiovascular/unexplained death) was 0.064 in the device group versus 0.063 in the control group (rate ratio 1.07 [95% credible interval (CrI): 0.57 to 1.89]) and did not achieve the prespecified criteria noninferiority (upper boundary of 95% CrI ≥1.75). The rate for the second coprimary efficacy endpoint (stroke or SE >7 days' postrandomization) was 0.0253 versus 0.0200 (risk difference 0.0053 [95% CrI: -0.0190 to 0.0273]), achieving noninferiority. Early safety events occurred in 2.2% of the Watchman arm, significantly lower than in PROTECT AF, satisfying the pre-specified safety performance goal. Using a broader, more inclusive definition of adverse effects, these still were lower in PREVAIL (Watchman LAA Closure Device in Patients With Atrial Fibrillation Versus Long Term Warfarin Therapy) trial than in PROTECT AF (4.2% vs. 8.7%; p = 0.004). Pericardial effusions requiring surgical repair decreased from 1.6% to 0.4% (p = 0.027), and those requiring pericardiocentesis decreased from 2.9% to 1.5% (p = 0.36), although the number of events was small.

CONCLUSIONS

In this trial, LAA occlusion was noninferior to warfarin for ischemic stroke prevention or SE >7 days' post-procedure. Although noninferiority was not achieved for overall efficacy, event rates were low and numerically comparable in both arms. Procedural safety has significantly improved. This trial provides additional data that LAA occlusion is a reasonable alternative to warfarin therapy for stroke prevention in patients with NVAF who do not have an absolute contraindication to short-term warfarin therapy.

Clinical usefulness of measuring prothrombin time and soluble fibrin levels in Japanese patients with atrial fibrillation receiving rivaroxaban

BACKGROUND

Rivaroxaban is currently used to prevent stroke in patients with atrial fibrillation. Measuring coagulation function may help clinicians to understand the effects of this drug and the associated risk of bleeding.

METHODS AND RESULTS

Rivaroxaban was given to 136 patients with non-valvular atrial fibrillation. Mean age was 74.5±9.0 years (men: 63.2%) and mean CHADS2 score (±SD) was 1.8±1.2. Prothrombin times (PTs) and plasma soluble fibrin (SF) levels were examined in 84 out of 136 patients at baseline and at least 2 weeks thereafter. In 48 patients we were able to collect blood at exact times, namely just before and 3h after rivaroxaban administration, corresponding to the trough and peak concentrations. Mean peak PT in 48 patients was 17.1±3.6s and median peak SF level was 1.46μg/mL. Multiple regression analysis showed that female sex, high brain natriuretic peptide, and high dose were independent factors prolonging the peak PT. Patients with peak PTs ≥20s experienced significantly more bleeding events. Among 29 of 46 patients newly treated with rivaroxaban without any previous anticoagulant, we examined coagulation function at the exact trough and peak times. In 29 patients, peak PT was significantly more prolonged than the baseline or trough PT (p<0.001 for both), whereas trough PT was comparable to the baseline PT. In contrast, both trough and peak SF levels in these newly treated patients were significantly reduced than at baseline (p=0.003 and p<0.001, respectively).

CONCLUSIONS

In Japanese patients with non-valvular atrial fibrillation receiving rivaroxaban, a prolonged peak PT (≥20s) could indicate increased risk of bleeding, and both trough and peak SF levels were reduced relative to baseline. PT and SF are both valuable measures of coagulation status in patients receiving rivaroxaban, regardless of prior anticoagulant history.

An audit of anticoagulant management to assess anticoagulant control using decision support software

OBJECTIVE

To evaluate the effectiveness of a computerised self-adjusting anticoagulant algorithm to predict appropriate warfarin dosing and to assess its use in clinical practice.

DESIGN

A 3-year audit of anticoagulant control in patients managed by doctors and pharmacists using computer decision support and an evaluation of the impact of dose adjustments made by the users.

PARTICIPANTS

3660 patients on oral anticoagulants; one-third of patients managed by doctors and two-thirds by pharmacists.

SETTING

Anticoagulant supervision in primary care and pharmacies at 60 sites in New Zealand.

MAIN OUTCOME MEASURES

The time in the therapeutic range (TTR), the outcome of adherence to the computer dosing algorithm, the percentage of time the clinicians over-ride the algorithm and the impact of their intervention on anticoagulant control.

RESULTS

A TTR of 72.9% was achieved for all patients. The TTR was significantly better in patients managed by pharmacists than doctors (75.1% versus 67.4%, p<0.0001). The computer algorithm provides appropriate dose recommendations for INR results from 1.5 to 4. Users administered a dose that differed from the computer recommendation 23.3% of the time. The doctors adjusted the dose more frequently (28.2% versus 21.1% of tests) and made larger dose changes than the pharmacists.

CONCLUSIONS

The clinicians predominantly change the dose when the INR is below the therapeutic range. The changes are not necessary to correct for inaccuracies in the algorithm. The most likely explanation is the clinician's belief that their own dose adjustment would achieve better control; however, in practice, their changes tend to underdose patients. The doctors achieved poorer control than the pharmacists; this is in part due to the action of the doctors over-riding the algorithm. Our results imply that clinicians could achieve better anticoagulant control if they more closely followed the computer algorithm.

Quality of vitamin K antagonist control and outcomes in atrial fibrillation patients: a meta-analysis and meta-regression

BACKGROUND

Atrial fibrillation (AF) patients frequently require anticoagulation with vitamin K antagonists (VKAs) to prevent thromboembolic events, but their use increases the risk of hemorrhage. We evaluated time spent in therapeutic range (TTR), proportion of international normalized ratio (INR) measurements in range (PINRR), adverse events in relation to INR, and predictors of INR control in AF patients using VKAs.

METHODS

We searched MEDLINE, CENTRAL and EMBASE (1990-June 2013) for studies of AF patients receiving adjusted-dose VKAs that reported INR control measures (TTR and PINRR) and/or reported an INR measurement coinciding with thromboembolic or hemorrhagic events. Random-effects meta-analyses and meta-regression were performed.

RESULTS

Ninety-five articles were included. Sixty-eight VKA-treated study groups reported measures of INR control, while 43 studies reported an INR around the time of the adverse event. Patients spent 61% (95% CI, 59-62%), 25% (95% CI, 23-27%) and 14% (95% CI, 13-15%) of their time within, below or above the therapeutic range. PINRR assessments were within, below, and above range 56% (95% CI, 53-59%), 26% (95% CI, 23-29%) and 13% (95% CI, 11-17%) of the time. Patients receiving VKA management in the community spent less TTR than those managed by anticoagulation clinics or in randomized trials. Patients newly receiving VKAs spent less TTR than those with prior VKA use. Patients in Europe/United Kingdom spent more TTR than patients in North America. Fifty-seven percent (95% CI, 50-64%) of thromboembolic events and 42% (95% CI, 35 - 51%) of hemorrhagic events occurred at an INR <2.0 and >3.0, respectively; while 56% (95% CI, 48-64%) of ischemic strokes and 45% of intracranial hemorrhages (95% CI, 29-63%) occurred at INRs <2.0 and >3.0, respectively.

CONCLUSIONS

Patients on VKAs for AF frequently have INRs outside the therapeutic range. While, thromboembolic and hemorrhagic events do occur patients with a therapeutic INR; patients with an INR <2.0 make up many of the cases of thromboembolism, while those >3.0 make up many of the cases of hemorrhage. Managing anticoagulation outside of a clinical trial or anticoagulation clinic is associated with poorer INR control, as is, the initiation of therapy in the VKA-naïve. Patients in Europe/UK have better INR control than those in North America.

Guidelines for gastroenterological endoscopy in patients undergoing antithrombotic treatment

Guidelines for gastroenterological endoscopy in patients undergoing antithrombotic treatment have been produced by the Japan Gastroenterological Endoscopy Society in collaboration with the Japan Circulation Society, the Japanese Society of Neurology, the Japan Stroke Society, the Japanese Society on Thrombosis and Hemostasis and the Japan Diabetes Society. Previous guidelines from the Japan Gastroenterological Endoscopy Society have focused primarily on prevention of hemorrhage after gastroenterological endoscopy as a result of continuation ofantithrombotic therapy, without considering the associated risk of thrombosis. The new edition of the guidelines includes discussions of gastroenterological hemorrhage associated with continuation of antithrombotic therapy, as well as thromboembolism associated with withdrawal of antithrombotic therapy.

Resolution of left atrial appendage thrombus with apixaban

Left atrial appendage (LAA) thrombosis is an important cause of cardiogenic cerebral thromboembolism. Apixaban is a member of the class of novel oral anticoagulants (NOAC) and is superior to warfarin in preventing stroke or systemic embolism, causes less bleeding, and results in lower mortality in patients with atrial fibrillation. There are few reports of resolution of LAA thrombus with other NOAC. We present a 72-year-old male patient with persistent atrial fibrillation associated with left atrial thrombus. Sixteen days of apixaban treatment showed complete thrombus resolution. In this study, soluble fibrin and D-dimer levels decreased without prolongation of international normalized ratio (INR) and activated partial thromboplastin time (APTT).

Spontaneous and non-spontaneous bleeding complications in patients with oral vitamin K antagonist therapy

PURPOSE

The aim of the study was to evaluate potential differences between patients with spontaneous and non-spontaneous bleeding episodes during treatment with vitamin K antagonists which mainly resulted in compartment syndromes.

METHODS

The population in this study comprised 116 patients who suffered at least one bleeding complication which required surgical treatment during therapy with an oral vitamin K antagonist. The patients were treated between September 2001 and July 2008.

RESULTS

Significant differences were observed between the two patient groups with regard to the presence of renal failure, arterial hypertension, and diabetes mellitus, which occurred more frequently in patients with spontaneous bleeding. Also, significantly more patients with spontaneous bleedings developed compartment syndrome that needed emergency operation. Overall mortality was 9.6 %, was associated with multiorgan failure in all patients, and was not different between the two patient groups.

CONCLUSIONS

The identification of high-risk patients before treatment with an oral vitamin K antagonist is of major importance. The existence of over-anticoagulation syndrome and compartment syndrome is associated with significant mortality and morbidity and should not be underestimated.

Management of Anticoagulant Therapy for Patients with Prosthetic Heart Valves or Atrial Fibrillation

There is a wide array of recommendations for the management of anticoagulant therapy in patients with mechanical heart valves. Especially the optimal intensity of vitamin K antagonists (VKA) is a ongoing matter of debate. On the basis of several studies, recommendations for daily clinical practice can be made. In this review, we discussed the studies and the different guidelines. Guidelines for the prevention of thromboembolic complications in patients with atrial fibrillation are more stringent. VKA with a target INR between 2.0 and 3.0 is more effective in the prevention of stroke than aspirin, especially in the presence of riskfactors for thromboembolism (age above 65, previous thromboembolism, history of hypertension and diabetes, enlarged left atrial diameter and left ventricular dysfunction). In the absence of clinical or echocardiographical riskfactors for thromboembolism, patients may be safely treated with aspirin.

A survey on adherence to secondary ischemic stroke prevention

Reduced adherence and compliance to discharge instructions and protocols could significantly influence the ability of any stroke prevention strategy. The goals of this investigation were to evaluate the adherence to secondary prevention strategies within 1 year after ischemic stroke and to identify possible causes of poor compliance with these strategies. Patients who had suffered either acute ischemic stroke or transient ischemic attacks (TIA) were recruited retrospectively through telephone follow-up. The survey included whether the patient was prescribed antithrombotic treatment at discharge and reasons for non-compliance with this prescription both immediately after discharge and 1 year after discharge. Of 472 (73.8%) patients with detailed clinical data who were finally evaluated in this survey, 326 (69.1%) were still under antithrombotic treatment and 172 (36.4%) underwent the same antithrombotic agent as prescribed when discharged. We found that medical insurance and free medical care were able to promote compliance with medication in stroke patients for secondary prevention, while administration of non-aspirin antithrombotic agents or a poor ability for daily activities (Barthel index, BI) had significantly negative effects on medication compliance in stroke patients. Under the conditions of this observational study, adherence to stroke prevention strategies was poor. Income levels, categories of antithrombotic agents and the personal living ability are closely related to compliance. The results suggest that doctors should pay more attention to the secondary prevention of stroke. We suggest that providing stroke patients with detailed instructions for medication usage, physicians could increase the potential that their secondary prevention of stroke could be increased.

The Impact of Antiplatelet and Anticoagulant Therapies on Gastrointestinal Symptoms in Patients with Atrial Fibrillation: A Systematic Review

BACKGROUND:

Patients with atrial fibrillation (AF) may be susceptible to gastrointestinal (GI) effects of medications used for thromboprophylaxis.

OBJECTIVE:

To determine the incidence of thromboprophylaxis discontinuation due to GI symptoms and GI events.

METHODS:

A systematic search of MEDLINE (1950-November 2011) and Cochrane Central (through third quarter of 2011) databases was conducted for randomized trials of adults with AF published in English full-text and reporting on discontinuation due to GI symptoms or the incidence of various GI symptoms.

RESULTS:

Of studies comparing oral direct thrombin inhibitors (DTIs) to vitamin K antagonists (VKAs), 67%, 100%, and 100% found significantly higher incidences of discontinuation due to GI symptoms, upper GI symptoms, and nondistinct GI symptoms with DTIs, respectively. When comparing aspirin to control therapy, 50% and 33% of trials found significantly higher incidences of discontinuation due to GI symptoms and nondistinct GI symptoms with aspirin, respectively. Aspirin significantly increased the incidence of upper GI symptoms compared to VKAs in 1 trial, but VKAs did not increase the incidence of discontinuation due to GI symptoms and nondistinct GI symptoms versus control. In the only trial comparing a factor Xa inhibitor to VKAs, no significant difference in diarrhea was seen, and when a factor Xa inhibitor was compared to aspirin, there was no significant difference in nondistinct GI symptoms. The incidence of discontinuation due to GI symptoms (4 trials) ranged from 0.0% to 0.4% for control, 0.0% to 2.4% for aspirin, 0.0% to 0.63% for VKA, and 1.2% to 4.7% for oral DTI recipients. The incidence of upper GI symptoms (2 trials) was 1.2% for aspirin, 0.0-5.8% for VKA, 4.2% for VKA plus aspirin, and 11.3-11.8% for DTI recipients. The incidence of nondistinct GI symptoms (7 trials) was 0.0-12.4% for control, 0.2-17.9% for aspirin, 0.0-14.1% for VKA, 23% for DTI, and 2.42% for factor Xa inhibitor recipients. Five trials evaluated diarrhea incidence, which ranged from 0.0% to 12.4% for VKA and 3.2% to 12.2% for oral DTI, and was 5.31% for factor Xa inhibitor recipients. One trial evaluated nausea, with incidences of 1.5% and 2.7% for VKA and DTI recipients, respectively.

CONCLUSIONS:

GI adverse events are common in AF trial populations. DTIs were associated with more discontinuations due to GI symptoms and aspirin appeared to increase the incidence of GI symptoms compared to control.

Novel anticoagulants in atrial fibrillation stroke prevention

This review article evaluates novel oral anticoagulants in comparison with warfarin for thromboembolism prophylaxis in patients with atrial fibrillation (AF). AF is the most frequently diagnosed arrhythmia in the United States. The most serious side effect of AF is stroke. Warfarin has several decades of proven efficacy in AF-related stroke prevention but the drug's numerous drawbacks make its implementation difficult for practitioners and patients. The difficulties of warfarin have prompted the development of alternative anticoagulants for AF-related stroke prevention with better efficacy, safety, and convenience. The oral direct thrombin inhibitor, dabigatran, and the oral factor Xa inhibitors, rivaroxaban and apixaban, have been evaluated in a large phase III trial. Dabigatran, rivaroxaban and apixaban were shown to be noninferior compared with warfarin in the prevention of stroke. Dabigatran and apixaban were found to be statistically superior to warfarin. All three may also have a better safety profile than warfarin. In conclusion, novel anticoagulants have a different pharmacologic profile compared with warfarin that may eliminate many of the treatment inconveniences. Practitioners must also be aware of the disadvantages these new drugs possess when choosing a management strategy for their patients. Drug selection may become clearer as these new drugs are used more extensively.