The Impact of Patient Self-Testing of Prothrombin Time for Managing Anticoagulation: Rationale and Design of VA Cooperative Study #481—The Home INR Study (THINRS)

Educational and behavioural interventions for anticoagulant therapy in patients with atrial fibrillation

BACKGROUND

Current guidelines recommend oral anticoagulation therapy for patients with atrial fibrillation (AF) with one or more risk factors for stroke; however, anticoagulation control (time in therapeutic range (TTR)) with vitamin K antagonists (VKAs) is dependent on many factors. Educational and behavioural interventions may impact patients' ability to maintain their international normalised ratio (INR) control. This is an updated version of the original review first published in 2013.

OBJECTIVES

To evaluate the effects of educational and behavioural interventions for oral anticoagulation therapy (OAT) on TTR in patients with AF.

SEARCH METHODS

We updated searches from the previous review by searching the Cochrane Central Register of Controlled Trials (CENTRAL) and the Database of Abstracts of Reviews of Effects (DARE) in The Cochrane Library (January 2016, Issue 1), MEDLINE Ovid (1949 to February week 1 2016), EMBASE Classic + EMBASE Ovid (1980 to Week 7 2016), PsycINFO Ovid (1806 to Week 1 February 2016) and CINAHL Plus with Full Text EBSCO (1937 to 16/02/2016). We applied no language restrictions.

SELECTION CRITERIA

We included randomised controlled trials evaluating the effect of any educational and behavioural intervention compared with usual care, no intervention, or intervention in combination with other self-management techniques among adults with AF who were eligible for, or currently receiving, OAT.

DATA COLLECTION AND ANALYSIS

Two of the review authors independently selected studies and extracted data. Risk of bias was assessed using the Cochrane 'Risk of bias' tool. We included outcome data on TTR, decision conflict (patient's uncertainty in making health-related decisions), percentage of INRs in the therapeutic range, major bleeding, stroke and thromboembolic events, patient knowledge, patient satisfaction, quality of life (QoL), beliefs about medication, illness perceptions, and anxiety and depression. We pooled data for three outcomes - TTR, anxiety and depression, and decision conflict - and reported mean differences (MD). Where insufficient data were present to conduct a meta-analysis, we reported effect sizes and confidence intervals (CI) from the included studies. We evaluated the quality of evidence using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) framework.

MAIN RESULTS

Eleven trials with a total of 2246 AF patients (ranging from 14 to 712 by study) were included within the review. Studies included education, decision aids, and self-monitoring plus education interventions. The effect of self-monitoring plus education on TTR was uncertain compared with usual care (MD 6.31, 95% CI -5.63 to 18.25, I2 = 0%, 2 trials, 69 participants, very low-quality evidence). We found small but positive effects of education on anxiety (MD -0.62, 95% CI -1.21 to -0.04, I2 = 0%, 2 trials, 587 participants, low-quality evidence) and depression (MD -0.74, 95% CI -1.34 to -0.14, I2 = 0%, 2 trials, 587 participants, low-quality evidence) compared with usual care. The effect of decision aids on decision conflict favoured usual care (MD -0.1, 95% CI -0.17 to -0.02, I2 = 0%, 2 trials, 721 participants, low-quality evidence).

AUTHORS' CONCLUSIONS

This review demonstrates that there is insufficient evidence to draw definitive conclusions regarding the impact of educational or behavioural interventions on TTR in AF patients receiving OAT. Thus, more trials are needed to examine the impact of interventions on anticoagulation control in AF patients and the mechanisms by which they are successful. It is also important to explore the psychological implications for patients suffering from this long-term chronic condition.

At-Home Versus In-Clinic INR Monitoring: A Cost-Utility Analysis from The Home INR Study (THINRS)

BACKGROUND

Effective management of patients using warfarin is resource-intensive, requiring frequent in-clinic testing of the international normalized ratio (INR). Patient self-testing (PST) using portable at-home INR monitoring devices has emerged as a convenient alternative. As revealed by The Home INR Study (THINRS), event rates for PST were not significantly different from those for in-clinic high-quality anticoagulation management (HQACM), and a cumulative gain in quality of life was observed for patients undergoing PST.

OBJECTIVE

To perform a cost-utility analysis of weekly PST versus monthly HQACM and to examine the sensitivity of these results to testing frequency.

PATIENTS/INTERVENTIONS

In this study, 2922 patients taking warfarin for atrial fibrillation or mechanical heart valve, and who demonstrated PST competence, were randomized to either weekly PST (n = 1465) or monthly in-clinic testing (n = 1457). In a sub-study, 234 additional patients were randomized to PST once every 4 weeks (n = 116) or PST twice weekly (n = 118). The endpoints were quality of life (measured by the Health Utilities Index), health care utilization, and costs over 2 years of follow-up.

RESULTS

PST and HQACM participants were similar with regard to gender, age, and CHADS2 score. The total cost per patient over 2 years of follow-up was $32,484 for HQACM and $33,460 for weekly PST, representing a difference of $976. The incremental cost per quality-adjusted life year gained with PST once weekly was $5566 (95 % CI, -$11,490 to $25,142). The incremental cost-effectiveness ratio (ICER) was sensitive to testing frequency: weekly PST dominated PST twice weekly and once every 4 weeks. Compared to HQACM, weekly PST was associated with statistically significant and clinically meaningful improvements in quality of life. The ICER for weekly PST versus HQACM was well within accepted standards for cost-effectiveness, and was preferred over more or less frequent PST. These results were robust to sensitivity analyses of key assumptions.

CONCLUSION

Weekly PST is a cost-effective alternative to monthly HQACM and a preferred testing frequency compared to twice weekly or monthly PST.

The clinical effectiveness and cost-effectiveness of point-of-care tests (CoaguChek system, INRatio2 PT/INR monitor and ProTime Microcoagulation system) for the self-monitoring of the coagulation status of people receiving long-term vitamin K antagonist therapy, compared with standard UK practice: systematic review and economic evaluation

BACKGROUND

Self-monitoring (self-testing and self-management) could be a valid option for oral anticoagulation therapy monitoring in the NHS, but current evidence on its clinical effectiveness or cost-effectiveness is limited.

OBJECTIVES

We investigated the clinical effectiveness and cost-effectiveness of point-of-care coagulometers for the self-monitoring of coagulation status in people receiving long-term vitamin K antagonist therapy, compared with standard clinic monitoring.

DATA SOURCES

We searched major electronic databases (e.g. MEDLINE, MEDLINE In Process & Other Non-Indexed Citations, EMBASE, Bioscience Information Service, Science Citation Index and Cochrane Central Register of Controlled Trials) from 2007 to May 2013. Reports published before 2007 were identified from the existing Cochrane review (major databases searched from inception to 2007). The economic model parameters were derived from the clinical effectiveness review, other relevant reviews, routine sources of cost data and clinical experts' advice.

REVIEW METHODS

We assessed randomised controlled trials (RCTs) evaluating self-monitoring in people with atrial fibrillation or heart valve disease requiring long-term anticoagulation therapy. CoaguChek(®) XS and S models (Roche Diagnostics, Basel, Switzerland), INRatio2(®) PT/INR monitor (Alere Inc., San Diego, CA USA), and ProTime Microcoagulation system(®) (International Technidyne Corporation, Nexus Dx, Edison, NJ, USA) coagulometers were compared with standard monitoring. Where possible, we combined data from included trials using standard inverse variance methods. Risk of bias assessment was performed using the Cochrane risk of bias tool. A de novo economic model was developed to assess the cost-effectiveness over a 10-year period.

RESULTS

We identified 26 RCTs (published in 45 papers) with a total of 8763 participants. CoaguChek was used in 85% of the trials. Primary analyses were based on data from 21 out of 26 trials. Only four trials were at low risk of bias. Major clinical events: self-monitoring was significantly better than standard monitoring in preventing thromboembolic events [relative risk (RR) 0.58, 95% confidence interval (CI) 0.40 to 0.84; p = 0.004]. In people with artificial heart valves (AHVs), self-monitoring almost halved the risk of thromboembolic events (RR 0.56, 95% CI 0.38 to 0.82; p = 0.003) and all-cause mortality (RR 0.54, 95% CI 0.32 to 0.92; p = 0.02). There was greater reduction in thromboembolic events and all-cause mortality through self-management but not through self-testing. Intermediate outcomes: self-testing, but not self-management, showed a modest but significantly higher percentage of time in therapeutic range, compared with standard care (weighted mean difference 4.44, 95% CI 1.71 to 7.18; p = 0.02). Patient-reported outcomes: improvements in patients' quality of life related to self-monitoring were observed in six out of nine trials. High preference rates were reported for self-monitoring (77% to 98% in four trials). Net health and social care costs over 10 years were £7295 (self-monitoring with INRatio2); £7324 (standard care monitoring); £7333 (self-monitoring with CoaguChek XS) and £8609 (self-monitoring with ProTime). The estimated quality-adjusted life-year (QALY) gain associated with self-monitoring was 0.03. Self-monitoring with INRatio2 or CoaguChek XS was found to have ≈ 80% chance of being cost-effective, compared with standard monitoring at a willingness-to-pay threshold of £20,000 per QALY gained.

CONCLUSIONS

Compared with standard monitoring, self-monitoring appears to be safe and effective, especially for people with AHVs. Self-monitoring, and in particular self-management, of anticoagulation status appeared cost-effective when pooled estimates of clinical effectiveness were applied. However, if self-monitoring does not result in significant reductions in thromboembolic events, it is unlikely to be cost-effective, based on a comparison of annual monitoring costs alone. Trials investigating the longer-term outcomes of self-management are needed, as well as direct comparisons of the various point-of-care coagulometers.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42013004944.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

The impact of frequency of patient self-testing of prothrombin time on time in target range within VA Cooperative Study #481: The Home INR Study (THINRS), a randomized, controlled trial

Anticoagulation (AC) is effective in reducing thromboembolic events for individuals with atrial fibrillation (AF) or mechanical heart valve (MHV), but maintaining patients in target range for international normalized ratio (INR) can be difficult. Evidence suggests increasing INR testing frequency can improve time in target range (TTR), but this can be impractical with in-clinic testing. The objective of this study was to test the hypothesis that more frequent patient-self testing (PST) via home monitoring increases TTR. This planned substudy was conducted as part of The Home INR Study, a randomized controlled trial of in-clinic INR testing every 4 weeks versus PST at three different intervals. The setting for this study was 6 VA centers across the United States. 1,029 candidates with AF or MHV were trained and tested for competency using ProTime INR meters; 787 patients were deemed competent and, after second consent, randomized across four arms: high quality AC management (HQACM) in a dedicated clinic, with venous INR testing once every 4 weeks; and telephone monitored PST once every 4 weeks; weekly; and twice weekly. The primary endpoint was TTR at 1-year follow-up. The secondary endpoints were: major bleed, stroke and death, and quality of life. Results showed that TTR increased as testing frequency increased (59.9 ± 16.7 %, 63.3 ± 14.3 %, and 66.8 ± 13.2 % [mean ± SD] for the groups that underwent PST every 4 weeks, weekly and twice weekly, respectively). The proportion of poorly managed patients (i.e., TTR <50 %) was significantly lower for groups that underwent PST versus HQACM, and the proportion decreased as testing frequency increased. Patients and their care providers were unblinded given the nature of PST and HQACM. In conclusion, more frequent PST improved TTR and reduced the proportion of poorly managed patients.

Educational and behavioural interventions for anticoagulant therapy in patients with atrial fibrillation

BACKGROUND

Current guidelines recommend oral anticoagulation therapy for patients with atrial fibrillation who are at moderate-to-high risk of stroke, however anticoagulation control (time in therapeutic range (TTR)) is dependent on many factors. Educational and behavioural interventions may impact on patients' ability to maintain their International Normalised Ratio (INR) control.

OBJECTIVES

To evaluate the effects on TTR of educational and behavioural interventions for oral anticoagulation therapy (OAT) in patients with atrial fibrillation (AF).

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) and the Database of Abstracts of Reviews of Effects (DARE) in The Cochrane Library (2012, Issue 7 of 12), MEDLINE Ovid (1950 to week 4 July 2012), EMBASE Classic + EMBASE Ovid (1947 to Week 31 2012), PsycINFO Ovid (1806 to 2012 week 5 July) on 8 August 2012 and CINAHL Plus with Full Text EBSCO (to August 2012) on 9 August 2012. We applied no language restrictions.

SELECTION CRITERIA

The primary outcome analysed was TTR. Secondary outcomes included decision conflict (patient's uncertainty in making health-related decisions), percentage of INRs in the therapeutic range, major bleeding, stroke and thromboembolic events, patient knowledge, patient satisfaction, quality of life (QoL), and anxiety.

DATA COLLECTION AND ANALYSIS

The two review authors independently extracted data. Where insufficient data were present to conduct a meta-analysis, effect sizes and confidence intervals (CIs) of the included studies were reported. Data were pooled for two outcomes, TTR and decision conflict.

MAIN RESULTS

Eight trials with a total of 1215 AF patients (number of AF participants included in the individual trials ranging from 14 to 434) were included within the review. Studies included education, decision aids, and self-monitoring plus education.For the primary outcome of TTR, data for the AF participants in two self-monitoring plus education trials were pooled and did not favour self-monitoring plus education or usual care in improving TTR, with a mean difference of 6.31 (95% CI -5.63 to 18.25). For the secondary outcome of decision conflict, data from two decision aid trials favoured usual care over the decision aid in terms of reducing decision conflict, with a mean difference of -0.1 (95% CI -0.2 to -0.02).

AUTHORS' CONCLUSIONS

This review demonstrated that there is insufficient evidence to draw definitive conclusions regarding the impact of educational or behavioural interventions on TTR in AF patients receiving OAT. Thus, more trials are needed to examine the impact of interventions on anticoagulation control in AF patients and the mechanisms by which they are successful. It is also important to explore the psychological implications for patients suffering from this long-term chronic condition.

Health related quality of life of patients undergoing oral anticoagulation therapy

This is a descriptive cross-sectional study, which aimed to analyze the health related quality of life (HRQoL) and its relationship with gender, age, duration and indication for the use of oral anticoagulants. A total of 178 patients were interviewed and the HRQoL was assessed through eight domains of the SF-36. The descriptive statistics used were, the Student's t, ANOVA and Tukey's tests for the comparison of the means between the groups. The indication for use was predominantly the metallic prosthetic heart valve (50%) with warfarin the most widely prescribed anticoagulant (83.3%). The means of the domains of the SF-36 ranged from 82 (Social aspects) to 54.8 (Physical aspects). Women, elderly, patients diagnosed with atrial fibrillation and with less than one year of medication use, presented a worse HRQoL evaluation. The results obtained can guide nursing actions, in that they indicate possible associations between the HRQoL and the sociodemographic and clinical variables of the patients.

An anticoagulation safety program in home care: identifying areas for improvement with an educational program for registered nurses and physical therapists

The 2008 National Patient Safety Goal program, directed by the Joint Commission (TJC), mandated safety improvements for anticoagulation therapy. In response, an urban, not-for-profit, Medicare-certified hospital Home Health Department identified the need to evaluate the Home Healthcare anticoagulation standards, safety practices, and patient/staff educational processes and materials. This Home Healthcare entity shall be referred to as the Agency for the purposes of this article.

Effect of home testing of international normalized ratio on clinical events

BACKGROUND

Warfarin anticoagulation reduces thromboembolic complications in patients with atrial fibrillation or mechanical heart valves, but effective management is complex, and the international normalized ratio (INR) is often outside the target range. As compared with venous plasma testing, point-of-care INR measuring devices allow greater testing frequency and patient involvement and may improve clinical outcomes.

METHODS

We randomly assigned 2922 patients who were taking warfarin because of mechanical heart valves or atrial fibrillation and who were competent in the use of point-of-care INR devices to either weekly self-testing at home or monthly high-quality testing in a clinic. The primary end point was the time to a first major event (stroke, major bleeding episode, or death).

RESULTS

The patients were followed for 2.0 to 4.75 years, for a total of 8730 patient-years of follow-up. The time to the first primary event was not significantly longer in the self-testing group than in the clinic-testing group (hazard ratio, 0.88; 95% confidence interval, 0.75 to 1.04; P=0.14). The two groups had similar rates of clinical outcomes except that the self-testing group reported more minor bleeding episodes. Over the entire follow-up period, the self-testing group had a small but significant improvement in the percentage of time during which the INR was within the target range (absolute difference between groups, 3.8 percentage points; P<0.001). At 2 years of follow-up, the self-testing group also had a small but significant improvement in patient satisfaction with anticoagulation therapy (P=0.002) and quality of life (P<0.001).

CONCLUSIONS

As compared with monthly high-quality clinic testing, weekly self-testing did not delay the time to a first stroke, major bleeding episode, or death to the extent suggested by prior studies. These results do not support the superiority of self-testing over clinic testing in reducing the risk of stroke, major bleeding episode, and death among patients taking warfarin therapy. (Funded by the Department of Veterans Affairs Cooperative Studies Program; ClinicalTrials.gov number, NCT00032591.).

Self-monitoring and self-management of oral anticoagulation

BACKGROUND

The introduction of portable monitors (point-of-care devices) for the management of patients on oral anticoagulation allows self-testing by the patient at home. Patients who self-test can either adjust their medication according to a pre-determined dose-INR schedule (self-management) or they can call a clinic to be told the appropriate dose adjustment (self-monitoring). Several trials of self-monitoring of oral anticoagulant therapy suggest this may be equal to or better than standard monitoring.

OBJECTIVES

To evaluate the effects of self-monitoring or self-management of oral anticoagulant therapy compared to standard monitoring.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2007, Issue 4), MEDLINE, EMBASE and CINAHL (to November 2007). We checked bibliographies and contacted manufacturers and authors of relevant studies. No language restrictions were applied.

SELECTION CRITERIA

Outcomes analysed were thromboembolic events, mortality, major haemorrhage, minor haemorrhage, tests in therapeutic range, frequency of testing, and feasibility of self-monitoring and self-management.

DATA COLLECTION AND ANALYSIS

The review authors independently extracted data. We used a fixed-effect model with the Mantzel-Haenzel method to calculate the pooled risk ratio (RR) and Peto's method to verify the results for uncommon outcomes. We examined heterogeneity amongst studies with the Chi(2) and I(2) statistics.

MAIN RESULTS

We identified 18 randomized trials (4723 participants). Pooled estimates showed significant reductions in both thromboembolic events (RR 0.50, 95% CI 0.36 to 0.69) and all-cause mortality (RR 0.64, 95% CI 0.46 to 0.89). This reduction in mortality remained significant after the removal of low-quality studies (RR 0.65, 95% CI 0.46 to 0.90). Trials of self-management alone showed significant reductions in thromboembolic events (RR 0.47, 95% CI 0.31 to 0.70) and all-cause mortality (RR 0.55, 95% CI 0.36 to 0.84); self-monitoring did not (thrombotic events RR 0.57, 95% CI 0.32 to 1.00; mortality RR 0.84, 95% CI 0.50 to 1.41). Self-monitoring significantly reduced major haemorrhages (RR 0.56, 95% CI 0.35 to 0.91) whilst self-management did not (RR 1.12, 95% CI 0.78 to 1.61). Twelve trials reported improvements in the percentage of mean INR measurements in the therapeutic range. No heterogeneity was identified in any of these comparisons.

AUTHORS' CONCLUSIONS

Compared to standard monitoring, patients who self-monitor or self-manage can improve the quality of their oral anticoagulation therapy. The number of thromboembolic events and mortality were decreased without increases in harms. However, self-monitoring or self-management were not feasible for up to half of the patients requiring anticoagulant therapy. Reasons included patient refusal, exclusion by their general practitioner, and inability to complete training.

Pharmacology and management of the vitamin K antagonists: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition)

This article concerning the pharmacokinetics and pharmacodynamics of vitamin K antagonists (VKAs) is part of the American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition). It describes the antithrombotic effect of the VKAs, the monitoring of anticoagulation intensity, and the clinical applications of VKA therapy and provides specific management recommendations. Grade 1 recommendations are strong and indicate that the benefits do or do not outweigh the risks, burdens, and costs. Grade 2 recommendations suggest that the individual patient's values may lead to different choices. (For a full understanding of the grading, see the "Grades of Recommendation" chapter by Guyatt et al, CHEST 2008; 133:123S-131S.) Among the key recommendations in this article are the following: for dosing of VKAs, we recommend the initiation of oral anticoagulation therapy, with doses between 5 mg and 10 mg for the first 1 or 2 days for most individuals, with subsequent dosing based on the international normalized ratio (INR) response (Grade 1B); we suggest against pharmacogenetic-based dosing until randomized data indicate that it is beneficial (Grade 2C); and in elderly and other patient subgroups who are debilitated or malnourished, we recommend a starting dose of < or = 5 mg (Grade 1C). The article also includes several specific recommendations for the management of patients with nontherapeutic INRs, with INRs above the therapeutic range, and with bleeding whether the INR is therapeutic or elevated. For the use of vitamin K to reverse a mildly elevated INR, we recommend oral rather than subcutaneous administration (Grade 1A). For patients with life-threatening bleeding or intracranial hemorrhage, we recommend the use of prothrombin complex concentrates or recombinant factor VIIa to immediately reverse the INR (Grade 1C). For most patients who have a lupus inhibitor, we recommend a therapeutic target INR of 2.5 (range, 2.0 to 3.0) [Grade 1A]. We recommend that physicians who manage oral anticoagulation therapy do so in a systematic and coordinated fashion, incorporating patient education, systematic INR testing, tracking, follow-up, and good patient communication of results and dose adjustments [Grade 1B]. In patients who are suitably selected and trained, patient self-testing or patient self-management of dosing are effective alternative treatment models that result in improved quality of anticoagulation management, with greater time in the therapeutic range and fewer adverse events. Patient self-monitoring or self-management, however, is a choice made by patients and physicians that depends on many factors. We suggest that such therapeutic management be implemented where suitable (Grade 2B).

Safety and effectiveness of point-of-care monitoring devices in patients on oral anticoagulant therapy: a meta-analysis

BACKGROUND

Point-of-care devices (POCDs) for monitoring long-term oral anticoagulation therapy (OAT) may be a useful alternative to laboratory-based international normalized ratio [INR] testing and clinical management.

PURPOSE

To determine clinical outcomes of the use of POCDs for OAT management by performing a meta-analysis. Previous meta-analyses on POCDs have serious limitations.

DATA SOURCES

PubMed, the Cochrane Library, DIALOG, MEDLINE, EMBASE, BIOSIS Previews and PASCAL databases.

STUDY SELECTION

Randomized controlled trials of patients on long-term OAT, comparing anticoagulation monitoring by POCD with laboratory INR testing and clinical management.

DATA EXTRACTION

1) rates of major hemorrhage; 2) rates of major thromboembolic events; 3) percentage of time that the patient is maintained within the therapeutic range; 4) deaths. Outcomes were compared using a random-effects model. Summary measures of rates were determined. The quality of studies was assessed using the Jadad scale.

DATA SYNTHESIS

Seventeen articles (16 studies) were included. Data analysis showed that POCD INR testing reduced the risk of major thromboembolic events (odds ratio [OR] = 0.51; 95% confidence interval [CI] 0.35-0.74), was associated with fewer deaths (OR = 0.58; 95% CI = 0.38-0.89), and resulted in better INR control compared with laboratory INR testing. No significant difference between the two management modalities with respect to odds ratios for major hemorrhage was found.

LIMITATIONS

Quality scores varied from 1 to 3 (out of a maximum of 5). Only 3 studies defined how thromboembolic events would be diagnosed, casting doubt on the accuracy of the reporting of thromboembolic events. The studies suggest that only 24% of patients are good candidates for self-testing and self-management. Compared with patients managed with laboratory-based monitoring, POCD patients underwent INR testing at a much higher frequency and received much more intensive education on OAT management.

CONCLUSIONS

The use of POCDs is safe and may be more effective than laboratory-based monitoring. However, most patients are not good candidates for self-testing and self-management. Patient education and frequency of testing may be the most important factors in successful PODC management. Definitive conclusions about the clinical benefits provided by self-testing and self-management require more rigorously designed trials.

Optimising stroke prevention in non-valvular atrial fibrillation

Atrial fibrillation is associated with substantial morbidity and mortality. Pooled data from trials comparing antithrombotic treatment with placebo have shown that warfarin reduces the risk of stroke by 62%, and that aspirin alone reduces the risk by 22%. Overall, in high-risk patients, warfarin is superior to aspirin in preventing strokes, with a relative risk reduction of 36%. Ximelagatran, an oral direct thrombin inhibitor, was found to be as efficient as vitamin K antagonist drugs in the prevention of embolic events, but has been recently withdrawn because of abnormal liver function tests. The ACTIVE-W (Atrial Fibrillation Clopidogrel Trial with Irbesartan for Prevention of Vascular Events) study has demonstrated that warfarin is superior to platelet therapy (clopidogrel plus aspirin) in the prevention af embolic events. Idraparinux, a Factor Xa inhibitor, is being evaluated in patients with atrial fibrillation. Angiotensin-converting enzyme inhibitors and angiotensin II receptor-blocking drugs hold promise in atrial fibrillation through cardiac remodelling. Preliminary studies suggest that statins could interfere with the risk of recurrence after electrical cardioversion. Finally, percutaneous methods for the exclusion of left atrial appendage are under investigation in high-risk patients.