Warfarin use following ischemic stroke among Medicare patients with atrial fibrillation

Prevention of cerebral thromboembolism by oral anticoagulation with dabigatran after pulmonary vein isolation for atrial fibrillation: the ODIn-AF trial

BACKGROUND AND OBJECTIVES

Long-term oral anticoagulation (OAC) following successful catheter ablation of atrial fibrillation (AF) remains controversial. Prospective data are missing. The ODIn-AF study aimed to evaluate the effect of OAC on the incidence of silent cerebral embolic events and clinically relevant cardioembolic events in patients at intermediate to high risk for embolic events, free from AF after pulmonary vein isolation (PVI).

METHODS

This prospective, randomized, multicenter, open-label, blinded endpoint interventional trial enrolled patients who were scheduled for PVI to treat paroxysmal or persistent AF. Six months after PVI, AF-free patients were randomized to receive either continued OAC with dabigatran or no OAC. The primary endpoint was the incidence of new silent micro- and macro-embolic lesions detected on brain MRI at 12 months of follow-up compared to baseline. Safety analysis included bleedings, clinically evident cardioembolic, and serious adverse events (SAE).

RESULTS

Between 2015 and 2021, 200 patients were randomized into 2 study arms (on OAC: n = 99, off OAC: n = 101). There was no significant difference in the occurrence of new cerebral microlesions between the on OAC and off OAC arm [2 (2%) versus 0 (0%); P = 0.1517] after 12 months. MRI showed no new macro-embolic lesion, no clinical apparent strokes were present in both groups. SAE were more frequent in the OAC arm [on OAC n = 34 (31.8%), off OAC n = 18 (19.4%); P = 0.0460]; bleedings did not differ.

CONCLUSION

Discontinuation of OAC after successful PVI was not found to be associated with an elevated risk of cerebral embolic events compared with continued OAC after a follow-up of 12 months.

Dabigatran must be used carefully: literature review and recommendations for management of adverse events

Atrial fibrillation increases the risk of stroke and death. The vitamin-K antagonist warfarin is recommended for patients with atrial fibrillation, but vitamin-K antagonists are cumbersome to use. Therefore, an effective, safe and convenient new anticoagulant is needed. Dabigatran acts by inhibiting free and fibrin-bound thrombin directly. It is an oral anticoagulant that was approved by the US Food and Drug Administration. The oral anticoagulant dabigatran has been used increasingly due to its good tolerance, predictable pharmacokinetics, effective anticoagulant effects, and absence of requirement of coagulation monitoring. However, an increasing prevalence of adverse events has been reported, some of them quite serious. Therefore, we searched and reviewed the literature on dabigatran with regard to adverse events, and proposed solutions to prevent and reduce the chance of adverse events occurring.

Effect of New Oral Anticoagulants on Prescribing Practices for Atrial Fibrillation in Older Adults

OBJECTIVES

To determine the effect of new oral anticoagulants (NOACs) on prescribing practices in older adults with atrial fibrillation (AF).

DESIGN

Retrospective observational cohort study.

SETTING

Academic medical center in St. Louis, Missouri.

PARTICIPANTS

Individuals aged 75 and older with AF admitted to the hospital from October 2010 through September 2015 (N = 6,568, 50% female, 15% non-white).

MEASUREMENTS

Information on NOACs and warfarin prescribed at discharge was obtained from hospital discharge summaries, and linear regression was used to examine quarterly trends in their use. Multivariable logistic regression was used to assess independent predictors of anticoagulant use.

RESULTS

NOAC use increased over time (correlation coefficient (r) = 0.87, P < .001), warfarin use did not change (r = -0.16, P = .50), and overall anticoagulant use (NOACs and warfarin) increased (r = 0.68, P = .001). NOAC use increased over time in all age groups (75-79, 80-84, 85-89) except aged 90 and older, but increasing age attenuated the rate of NOAC uptake. There was no consistent relationship between age and warfarin or overall anticoagulant use, except that individuals aged 90 and older had consistently lower use. Overall, fewer than 45% of participants were prescribed an anticoagulant. In multivariable analysis, younger age, white race, female sex, higher hemoglobin, higher creatinine clearance, being on a medical service, hypertension, stroke or transient ischemic attack, no history of intracranial hemorrhage, and a modified HAS-BLED score of less than 3 increased the likelihood of receiving NOACs.

CONCLUSION

Prescription of anticoagulants for AF increased in older adults primarily because of an increase in the use of NOACs. Nonetheless, fewer than 45% of participants were prescribed an anticoagulant. Additional research is needed to optimize prescribing practices for older adults with AF.

Impact of Warfarin on Atrial-Fibrillation Outcomes Related to Economic Consumption Patterns: Hospitalization, Cost, and Mortality may be Predictable and Modifiable at the Population Level

INTRODUCTION

Warfarin reduces atrial fibrillation (AF)-related strokes and may impact mortality, hospitalizations, and costs. This study investigated the possibility that patterns of warfarin consumption are associated with the frequency of acute events.

METHODS

Annual cost profiles of 9.2 million Medicare beneficiaries with AF were analyzed to identify patterns of benefits consumption from 2000 through 2010. Beneficiaries were divided into five consumption clusters based upon their annual cost profiles, ranging from crisis consumers at the high end to low consumers. Resource-utilization patterns and outcome differences were calculated between AF beneficiaries who received warfarin and those who did not. Propensity score-matched analysis was performed to reduce selection bias.

RESULTS

The annual percentages of beneficiaries and expenditures that differentiated each cluster showed stable patterns. Warfarin use influenced consumption patterns and outcomes. The most important financial difference between higher and lower consumers was inpatient cost. AF beneficiaries on warfarin had lower annual cost profiles and had a higher propensity to persist in or migrate to consumption clusters with comparatively small reimbursement claims and lower hospitalization risks. AF beneficiaries not on warfarin had higher cost and mortality.

CONCLUSIONS

These data signal that a nontrivial portion of acute events (hospitalization and mortality) are amenable to medical intervention (warfarin). When acute events are amenable to medical intervention and occur at a higher frequency because guidelines have not been applied evenly across affected populations, it is appropriate to define those occurrences as disparities associated with systemic failure in evidence-based medicine. Quality-improvement initiatives that reduce therapeutic disparities may result in lower cost and improved outcomes.

FUNDING

No funding or sponsorship was received for this study or publication of this article.

Medical Management of Patients with an Acute Stroke: Treatment and Prevention

Stroke is a common and serious disorder and will probably occur with increasing frequency due to an aging of the population. Acute therapies aimed at reversing the effects of acute ischemic stroke are limited to recombinant tissue plasminogen activator administered intravenously within 3 hours of stroke onset. Neuroprotective agents and acute anticoagulation with agents such as heparinoids and heparin are not effective in most cases. Poststroke medical complications such as infection and venous thromboembolism are common but are largely preventable. A variety of medical therapies such as antiplatelet agents, warfarin, statins, and ACE inhibitors can reduce the risk of a recurrent stroke. A key aspect of management for stroke is selection of the proper treatment regimen for each patient.

Risk scores and geriatric profile: can they really help us in anticoagulation decision making among older patients suffering from atrial fibrillation?

OBJECTIVES

Anticoagulation for the prevention of cardio-embolism is most frequently indicated but largely underused in frail older patients with atrial fibrillation (AF). This study aimed at identifying characteristics associated with anticoagulation underuse.

METHODS

A cross-sectional study of consecutive geriatric patients aged ≥75 years, with AF and clear anticoagulation indication (CHADS₂ [Congestive heart failure, Hypertension, Age >75, Diabetes mellitus, and prior Stroke or transient ischemic attack] ≥2) upon hospital admission. All patients benefited from a comprehensive geriatric assessment. Their risks of stroke and bleeding were predicted using CHADS₂ and HEMORR2HAGES (Hepatic or renal disease, Ethanol abuse, Malignancy, Older (age >75 years), Reduced platelet count or function, Rebleed risk, Hypertension (uncontrolled), Anemia, Genetic factors, Excessive fall risk, and Stroke) scores, respectively.

RESULTS

Anticoagulation underuse was observed in 384 (50%) of 773 geriatric patients with AF (median age 85 years; female 57%, cognitive disorder 33%, nursing home 20%). No geriatric characteristic was found to be associated with anticoagulation underuse. Conversely, anticoagulation underuse was markedly increased in the patients treated with aspirin (odds ratio [OR] [95% confidence interval]: 5.3 [3.8; 7.5]). Other independent predictors of anticoagulation underuse were ethanol abuse (OR: 4.0 [1.4; 13.3]) and age ≥90 years (OR: 2.0 [1.2; 3.4]). Anticoagulation underuse was not inferior in patients with a lower bleeding risk and/or a higher stroke risk and underuse was surprisingly not inferior either in the AF patients who had previously had a stroke.

CONCLUSION

Half of this geriatric population did not receive any anticoagulation despite a clear indication, regardless of their individual bleeding or stroke risks. Aspirin use is the main characteristic associated with anticoagulation underuse.

Impact of stated barriers on proposed warfarin prescription for atrial fibrillation: a survey of Canadian physicians

BACKGROUND

Atrial fibrillation (AF) is a common cardiac arrhythmia, and leading cause of ischemic stroke. Despite proven effectiveness, warfarin remains an under-used treatment in atrial fibrillation patients. We sought to study, across three physician specialties, a range of factors that have been argued to have a disproportionate effect on treatment decisions.

METHODS

Cross-sectional survey of Canadian Family Doctors (FD: n = 500), Geriatricians (G: n = 149), and Internal Medicine specialists (IMS: n = 500). Of these, 1032 physicians were contactable, and 335 completed and usable responses were received. Survey questions and clinical vignettes asked about the frequency with which they see patients with atrial fibrillation, treatment practices, and barriers to the prescription of anticoagulants.

RESULTS

Stated prescribing practices did not significantly differ between physician groups. Falls risk, bleeding risk and poor patient adherence were all highly cited barriers to prescribing warfarin. Fewer geriatricians indicated that history of patient falls would be a reason for not treating with warfarin (G: 47%; FD: 71%; IMS: 72%), and significantly fewer changed reported practice in the presence of falls risk (χ (2) (6) = 45.446, p < 0.01). Experience of a patient having a stroke whilst not on warfarin had a significant impact on vignette decisions; physicians who had had patients who experienced a stroke were more likely to prescribe warfarin (χ (2) (3) =10.7, p = 0.013).

CONCLUSIONS

Barriers to treatment of atrial fibrillation with warfarin affect physician specialties to different extents. Prior experience of a patient suffering a stroke when not prescribed warfarin is positively associated with intention to prescribe warfarin, even in the presence of falls risk.

A Pharmacokinetic Study of the Combined Administration of Amiodarone and Ximelagatran, an Oral Direct Thrombin Inhibitor

The oral direct thrombin inhibitor ximelagatran is being developed for the prevention and treatment of thromboembolism. This single-blind, randomized, placebo-controlled, parallel-group study investigated the potential for the interaction of ximelagatran (36 mg every 12 hours for 8 days, measured as its active form melagatran in blood) and amiodarone (single 600-mg oral dose on day 4) in healthy male subjects (n = 26). For amiodarone + ximelagatran versus amiodarone + placebo, geometric mean ratios (90% confidence intervals for amiodarone AUC(0-120) and C(max) were 0.87 (0.69-1.08) and 0.86 (0.66-1.11), respectively. For desethylamiodarone, the principal metabolite of amiodarone, the corresponding ratios were 1.00 (0.89-1.12) for AUC(0-120) and 0.92 (0.77-1.09) for C(max). The geometric mean ratios (90% confidence intervals) for ximelagatran + amiodarone versus ximelagatran were 1.21 (1.17-1.25) for melagatran AUC(0-12) and 1.23 (1.18-1.28) for melagatran C(max). These confidence intervals were within or only slightly outside the interval, suggesting no interaction (0.8-1.25 for the effect of amiodarone on melagatran and 0.7-1.43 for the effect of melagatran on amiodarone or desethylamiodarone). Amiodarone did not affect the concentration-effect relationship of melagatran on activated partial thromboplastin time. Ximelagatran was well tolerated when coadministered with a single dose of amiodarone. Evaluation of the safety of the combination is needed to confirm that the relatively small pharmacokinetic changes in this study are of no clinical significance.

Percutaneous left atrial appendage suture ligation using the LARIAT device in patients with atrial fibrillation: initial clinical experience

OBJECTIVES

The purpose of the study was to determine the efficacy and safety of left atrial appendage (LAA) closure via a percutaneous LAA ligation approach.

BACKGROUND

Embolic stroke is the most devastating consequence of atrial fibrillation. Exclusion of the LAA is believed to decrease the risk of embolic stroke.

METHODS

Eighty-nine patients with atrial fibrillation were enrolled to undergo percutaneous ligation of the LAA with the LARIAT device. The catheter-based LARIAT device consists of a snare with a pre-tied suture that is guided epicardially over the LAA. LAA closure was confirmed with transesophageal echocardiography (TEE) and contrast fluoroscopy immediately, then with TEE at 1 day, 30 days, 90 days, and 1 year post-LAA ligation.

RESULTS

Eighty-five (96%) of 89 patients underwent successful LAA ligation. Eighty-one of 85 patients had complete closure immediately. Three of 85 patients had a ≤ 2-mm residual LAA leak by TEE color Doppler evaluation. One of 85 patients had a ≤ 3-mm jet by TEE. There were no complications due to the device. There were 3 access-related complications (during pericardial access, n = 2; and transseptal catheterization, n = 1). Adverse events included severe pericarditis post-operatively (n = 2), late pericardial effusion (n = 1), unexplained sudden death (n = 2), and late strokes thought to be non-embolic (n = 2). At 1 month (81 of 85) and 3 months (77 of 81) post-ligation, 95% of the patients had complete LAA closure by TEE. Of the patients undergoing 1-year TEE (n = 65), there was 98% complete LAA closure, including the patients with previous leaks.

CONCLUSIONS

LAA closure with the LARIAT device can be performed effectively with acceptably low access complications and periprocedural adverse events in this observational study.

Predictors of warfarin use in atrial fibrillation in the United States: a systematic review and meta-analysis

BACKGROUND

Despite warfarin's marked efficacy, not all eligible patients receive it for stroke prevention in AF. The aim of this meta-analysis was to evaluate the association between prescriber and/or patient characteristics and subsequent prescription of warfarin for stroke prevention in patients with atrial fibrillation (AF).

METHODS

Observational studies conducted in the US using multivariate analysis to determine the relationship between characteristics and the odds of receiving warfarin for stroke prevention were identified in MEDLINE, EMBASE and a manual review of references. Effect estimates of prescriber and/or patient characteristics from individual studies were pooled to calculate odds ratios (ORs) with 95% confidence intervals.

RESULTS

Twenty-eight studies reporting results of 33 unique multivariate analyses were identified. Warfarin use across studies ranged from 9.1%-79.8% (median=49.1%). There was a moderately-strong correlation between warfarin use and year of study (r=0.60, p=0.002). Upon meta-analysis, characteristics associated with a statistically significant increase in the odds of warfarin use included history of cerebrovascular accident (OR=1.59), heart failure (OR=1.36), and male gender (OR=1.12). Those associated with a significant reduction in the odds of warfarin use included alcohol/drug abuse (OR=0.62), perceived barriers to compliance (OR=0.87), contraindication(s) to warfarin (OR=0.81), dementia (OR=0.32), falls (OR=0.60), gastrointestinal hemorrhage (OR=0.47), intracranial hemorrhage (OR=0.39), hepatic (OR=0.59), and renal impairment (OR=0.69). While age per 10-year increase (OR=0.78) and advancing age as a dichotomized variable (cut-off varied by study) (OR=0.57) were associated with significant reductions in warfarin use; qualitative review of results of studies evaluating age as a categorical variable did not confirm this relationship.

CONCLUSIONS

Warfarin use has increased somewhat over time. The decision to prescribe warfarin for stroke prevention in atrial fibrillation is based upon multiple prescriber and patient characteristics. These findings can be used by family practice prescribers and other healthcare decision-makers to target interventions or methods to improve utilization of warfarin when it is indicated for stroke prevention.

Underuse of oral anticoagulants in atrial fibrillation: a systematic review

BACKGROUND

Atrial fibrillation is associated with substantial mortality and morbidity from stroke and thromboembolism. Despite an efficacious oral anticoagulation therapy (warfarin), atrial fibrillation patients at high risk for stroke are often under-treated. This systematic review compares current treatment practices for stroke prevention in atrial fibrillation with published guidelines.

METHODS

Literature searches (1997-2008) identified 98 studies concerning current treatment practices for stroke prevention in atrial fibrillation. The percentage of patients eligible for oral anticoagulation due to elevated stroke risk was compared with the percentage treated. Under-treatment was defined as treatment of <70% of high-risk patients.

RESULTS

Of 54 studies that reported stroke risk levels and the percentage of patients treated, most showed underuse of oral anticoagulants for high-risk patients. From 29 studies of patients with prior stroke/transient ischemic attack who should all receive oral anticoagulation according to published guidelines, 25 studies reported under-treatment, with 21 of 29 studies reporting oral anticoagulation treatment levels below 60% (range 19%-81.3%). Subjects with a CHADS(2) (congestive heart failure, hypertension, age >75 years, diabetes mellitus, and prior stroke or transient ischemic attack) score >or=2 also were suboptimally treated, with 7 of 9 studies reporting treatment levels below 70% (range 39%-92.3%). Studies (21 of 54) using other stroke risk stratification schemes differ in the criteria they use to designate patients as "high risk," such that direct comparison is not possible.

CONCLUSIONS

This systematic review demonstrates the underuse of oral anticoagulation therapy for real-world atrial fibrillation patients with an elevated risk of stroke, highlighting the need for improved therapies for stroke prevention in atrial fibrillation.

Dabigatran Etexilate: Future Directions in Anticoagulant Treatment

Dabigatran etexilate is a novel, oral reversible direct thrombin inhibitor in the clinical development for the treatment and prevention of thromboembolic diseases. Clinical data indicate that dabigatran etexilate has immediate onset of effect, no need for monitoring, predictable and consistent pharmacokinetics and pharmacodynamics—all features that differentiate it from oral vitamin K antagonists (VKAs). Completed phase III studies demonstrated a comparable efficacy and safety profile to enoxaparin in the prevention of venous thromboembolism (VTE) after orthopedic surgery. Ongoing phase III trials are now evaluating the long-term use of dabigatran etexilate for the treatment and secondary prevention of VTE and for prevention of stroke in patients with atrial fibrillation, as a replacement for VKAs. With an immediate, reliable, and predictable anticoagulant effect without the need for coagulation monitoring and the lack of long-term safety concerns, dabigatran etexilate may be a prospective candidate that offers additional benefit over VKAs and parenteral anticoagulants in these settings.

Rationale and design of RE-LY: randomized evaluation of long-term anticoagulant therapy, warfarin, compared with dabigatran

Vitamin K antagonists (VKAs) are effective for stroke prevention in patients with atrial fibrillation (AF) but are difficult to use. Dabigatran etexilate is a prodrug that is rapidly converted to the active direct thrombin inhibitor dabigatran. It is administered in a fixed dose without laboratory monitoring and is being compared with warfarin (international normalized ratio 2-3) in the RE-LY trial. Two doses of dabigatran (110 and 150 mg BID) are being evaluated. RE-LY is a phase 3, prospective, randomized, open-label multinational (44 countries) trial of patients with nonvalvular AF and at least 1 risk factor for stroke. Recruitment concluded with a total of 18,113 patients. Patients who were VKA-naive and experienced are included in balanced proportions. The primary outcome is stroke (including hemorrhagic) or systemic embolism. Safety outcomes are bleeding, liver function abnormalities, and other adverse events. Adjudication of end points is blinded to drug assignment. The trial is expected to accrue a minimum of 450 events with a minimum 1-year of follow-up. RE-LY is the largest AF stroke prevention trial yet undertaken. It is unique because it includes equal numbers of VKA-experienced and naive patients and evaluates 2 different dosages of dabigatran, which may allow tailoring of dosing to individual patient needs. The worldwide site distribution and broad range of stroke risk further increase the general applicability of the trial. Results are expected in 2009.

Clinical epidemiology of atrial fibrillation and related cerebrovascular events in the United States

BACKGROUND

Atrial fibrillation (AF) is an important, independent risk factor for stroke and is estimated to cause a 5-fold increase in ischemic stroke risk. The aim of this article is to describe the changing epidemiology of AF in the United States and to assess the implications for stroke prevention and treatment.

REVIEW SUMMARY

AF prevalence is increasing in the general population. This is likely due to the aging of the population, the improvements in coronary care and the rising prevalence of AF risk factors such as diabetes. Risk factors such as rheumatic heart disease and hypertension have decreased in prevalence over the past few decades. However, novel risk factors such as obesity and possibly the metabolic syndrome have been identified and these have the potential to further increase AF prevalence. The utilization of warfarin has improved and this is reflected in falling ischemic stroke rates in the AF population. There is evidence for an increased incidence of anticoagulant associated intraparenchymal hemorrhages during the 1990s.

CONCLUSIONS

Although the decline in stroke rates in AF is laudable, the rising prevalence of AF, the changing profile of risk factors, and the recent plateauing of warfarin use indicate that stroke in AF patients will continue to be a significant public health problem.

Improving outpatient warfarin use for hospitalized patients with atrial fibrillation

Atrial fibrillation affects an estimated 5 million Americans and accounts for approximately 15% of all strokes. Few studies have successfully addressed patient screening, assessment, and introduction of appropriate antithrombotic therapy in patients with atrial fibrillation.

Implementing hospital guidelines improves warfarin use in non-valvular atrial fibrillation: a before-after study

BACKGROUND

The use of oral anticoagulant therapy (OAT) to prevent non-valvular atrial fibrillation (NVAF) related-strokes is often sub-optimal. We aimed to evaluate whether implementing guidelines on antithrombotic therapy (AT) by a multifaceted strategy may improve appropriateness of its prescription in NVAF-patients discharged from a large tertiary-care hospital.

METHODS

A survey was conducted on all consecutive NVAF patients discharged before (1st January-30th June 2000, n = 313) and after (1st January-30th June 2004, n = 388) guideline development and implementation.

RESULTS

When strongly recommended, OAT use increased from 56.6% (60/106 in 2000) to 81.9% (86/105 in 2004), with an absolute difference of +25.3% (95%CI: 15% 35%). In patients for whom the choice OAT/acetylsalicylic acid should be individualised, those discharged without any AT were 33.7% (34/101) in 2000 and 16.9% (21/124) in 2004 (-16.7%;95%CI: -26.2% -7.2%). In a logistic regression model, OAT prescription in 2004 was increased by 2.11 times (95%CI: 1.47 3.04), after accounting for stroke risk, presence of contraindications (OR = 0.18; 0.13 0.27), older age (OR = 0.30; 0.21 0.45), prophylaxis at admission (OR = 3.03; 2.08 4.43). OAT was positively associated with the stroke risk in the 2004 sample only.

CONCLUSION

The guideline implementation has substantially improved the appropriateness of OAT at discharge, through a better evaluation at patient's individual level of the benefit-to-risk ratio.

WITHDRAWN: Anticoagulants or antiplatelet therapy for non-rheumatic atrial fibrillation and flutter

BACKGROUND

Atrial fibrillation (AF) carries a high risk of stroke and other thromboembolic events. Appropriate use of drugs to prevent thromboembolism in patients with AF involves comparing the patient's risk of stroke to the risk of hemorrhage from medication use.

OBJECTIVES

To quantify risk of stroke, major hemorrhage and death from using medications that have been rigorously evaluated for prevention of thromboembolism in AF.

SEARCH STRATEGY

Articles were identified through the Cochrane Collaboration's CENTRAL database and MEDLINE until December 1999.

SELECTION CRITERIA

Included Randomized controlled trials of drugs to prevent thromboembolism in adults with non-postoperative AF. Excluded RCTS of patients with rheumatic valvular disease.

DATA COLLECTION AND ANALYSIS

Data were abstracted by two reviewers. Odds ratios from all qualitatively similar studies were combined, with weighting by study size, to yield aggregate odds ratios for stroke, major hemorrhage, and death for each drug.

MAIN RESULTS

Fourteen articles were included in this review. Warfarin was more efficacious than placebo for primary stroke prevention {aggregate odds ratio (OR) of stroke=0.30 [95% Confidence Interval (C.I.) 0.19,0.48]}, with moderate evidence of more major bleeding { OR= 1.90 [95% C.I. 0.89,4.04].}. Aspirin was inconclusively more efficacious than placebo for stroke prevention {OR=0.68 [95% C.I. 0.29,1.57]}, with inconclusive evidence regarding more major bleeds {OR=0.81[95% C.I. 0.37,1.78]}. For primary prevention, assuming a baseline risk of 45 strokes per 1000 patient-years, warfarin could prevent 30 strokes at the expense of only 6 additional major bleeds. Aspirin could prevent 17 strokes, without increasing major hemorrhage. In direct comparison, there was moderate evidence for fewer strokes among patients on warfarin than on aspirin {aggregate OR=0.64[95% C.I. 0.43,0.96]}, with only suggestive evidence for more major hemorrhage {OR =1.58 [95% C.I. 0.76,3.27]}. However, in younger patients, with a mean age of 65 years, the absolute reduction in stroke rate with warfarin compared to aspirin was low (5.5 per 1000 person-years) compared to an older group (15 per 1000 person-years). Low-dose warfarin or low-dose warfarin with aspirin was less efficacious for stroke prevention than adjusted-dose warfarin.

AUTHORS' CONCLUSIONS

The evidence strongly supports warfarin in AF for patients at average or greater risk of stroke, although clearly there is a risk of hemorrhage. Although not definitively supported by the evidence, aspirin may prove to be useful for stroke prevention in sub-groups with a low risk of stroke, with less risk of hemorrhage than with warfarin. Further studies are needed of low- molecular weight heparin and aspirin in lower risk patients.

First-Ever Ischemic Stroke in Very Old Asians: Clinical Features, Stroke Subtypes, Risk Factors and Outcome

BACKGROUND

Prior studies have been conducted in very old white and black patients. However, stroke in very old Asians has not been studied.

METHODS

This study retrospectively reviewed the records of first-ever ischemic stroke patients admitted to the Chiayi Chang Gung Memorial Hospital in the middle part of Taiwan from January 2002 to December 2005. Clinical features, stroke subtypes, risk factors, acute ward mortality, length of acute ward stay, medical complications and medication for secondary stroke prevention at discharge were compared in 2 groups of first-ever ischemic stroke patients (one > or =80 and the other <80 years old).

RESULTS

Aged patients (> or =80 years old) had a higher proportion of conscious impairment at admission, a longer acute ward stay, a higher incidence of total anterior circulation infarct and a lower frequency of lacunar infarct, more frequent atrial fibrillation and less frequent diabetes mellitus, hyperlipidemia and smoking habits, and a higher incidence of pneumonia, urinary tract infection and upper gastrointestinal bleeding.

CONCLUSIONS

Understanding the risk factors and medical complications in very old stroke patients may help improve the stroke prevention strategy and the quality of stroke patient management.

Reduced Medication Access

Background and Purpose— Medication access is crucial to secondary stroke prevention. We assessed medication access and associated barriers to care across region and time in a national sample of US stroke survivors.

Methods— Among all 5840 black or white stroke survivors aged ≥45 years responding to the National Health Interview Survey years 1997 to 2004, we examined inability to afford medications within the last 12 months across region (Northeast, Midwest, West, South) and time. With logistic regression, we adjusted associations between medication inaffordability and region and time for age, sex, race, neurological disability, comorbidity, health status, insurance, income and out-of-pocket medical expenses.

Results— In 2004, ≈76 000 US stroke survivors were unable to afford medications. Lower medication affordability was reported among stroke survivors who were <65 years old, black, female, had high comorbidity or low health status. Compared with stroke survivors able to afford medications, those unable more frequently reported lack of transportation (15% versus 3%; P <0.001), no health insurance (16% versus 3%; P <0.001), no usual place of care (6% versus 2%; P =0.001), income <$20 000 (66% versus 40%; P <0.001) and out-of-pocket medical expenses ≥$2000 (35% versus 25%; P <0.001). From 1997 to 2004, inability to afford medications increased significantly from 8.1% to 12.7% (P trend =0.01) overall and increased in all US regions except the Northeast.

Conclusions— We identified a vulnerable stroke survivor population with reduced medication access and increased barriers to medical care. Membership in this population has grown substantially from 1997 to 2004, potentially leading to increased recurrent stroke incidence.

Anticoagulation for Atrial Fibrillation in the Elderly

Atrial fibrillation is a risk factor for stroke, particularly among elderly patients. Multiple trials have established that antithrombotic therapy decreases stroke risk. Aspirin is associated with a relative risk reduction of about 21% and adjusted-dose warfarin (international normalized ratio 2.0-3.0) is associated with a relative risk reduction of about 68%. Warfarin is more effective than aspirin but is used less often than indicated because of hemorrhagic risk and the inconvenience of coagulation monitoring. The oral direct thrombin ximelagatran has been investigated for stroke prevention in patients with atrial fibrillation in two large clinical trials. The results suggest efficacy in a fixed dose compared with well controlled warfarin. Although anticoagulation intensity was not monitored or regulated during treatment with ximelagatran, it was associated with less bleeding than warfarin. Other antithrombotic agents are under development as alternatives to warfarin, but sufficient data are not yet available to justify their clinical use in patients with atrial fibrillation.

Antithrombotic drug prescription in atrial fibrillation and its rationale among general practitioners, internists and cardiologists in The Netherlands--The EXAMINE-AF study. A questionnaire survey

The objective of the EXAMINE-AF study was to record and compare antithrombotic treatment in patients with atrial fibrillation (AF) in daily clinical practice of general practitioners, internists and cardiologists in the Netherlands. Eighty-six general practitioners, 93 internists and 99 cardiologists responded to postal questionnaires and enrolled 1596 patients: 365, 351 and 880 respectively. A cardiologist was indicated to be the main treating physician for AF in 82% of all patients; current antithrombotic treatment was initiated in 80% by a cardiologist. Of all patients, 84% were at high risk for stroke and therefore were eligible for oral anticoagulation treatment, but only 64% actually received this. Cardiologists instituted appropriate antithrombotic treatment best, compared with general practitioners and internists (70% vs. 58% and 55%; p < 0.001). Positive predictive factors for oral anticoagulation prescription were previous stroke/transient ischaemic attack (OR, 2.31; 95% CI, 1.33-4.02) and heart failure (OR, 1.72; 95% CI, 1.23-2.42). Contraindications for oral anticoagulation (OR, 0.46; 95% CI, 0.32-0.68), treatment by a general practitioner (OR, 0.29; 95% CI, 0.20-0.42) or internist (OR, 0.24; 95% CI, 0.15-0.39) were important factors for withholding treatment. Antithrombotic treatment in AF patients is well instituted in primary and secondary care in the Netherlands. Cardiologists play a key role in the diagnosis and management of the majority of AF patients, even in those regularly attending other physicians. Factors for oral anticoagulation prescription are heart failure, physician specialty and contraindications. Availability of guidelines seems instrumental for application of appropriate antithrombotic treatment.

Underinvestigation and undertreatment of carotid disease in elderly patients with transient ischaemic attack and stroke: comparative population based study

OBJECTIVE

To identify any underinvestigation of older patients with transient ischaemic attack (TIA) and stroke.

DESIGN

Comparative population based studies.

SETTING

Routine clinical practice in all secondary care services in Oxfordshire and a nested population based study of incidence of transient ischaemic attack and stroke (the Oxford vascular study-OXVASC). PARTICIPANTS/POPULATION: All patients undergoing carotid imaging for ischaemic retinal or cerebral transient ischaemic attack or stroke from 1 April 2002 to 31 March 2005 in the Oxford vascular study (n = 91,105) and from 1 April 2002 to 31 March 2003 in routine clinical practice (n = 589,899).

MAIN OUTCOME MEASURES

Age specific rates of carotid imaging, diagnosed >or= 50% symptomatic carotid stenosis, and subsequent endarterectomy, in patients with recent transient ischaemic attack or stroke.

RESULTS

Of patients with recent carotid territory transient ischaemic attack or ischaemic stroke, 575 in routine clinical practice and 402 in the Oxford vascular study had carotid imaging, with similar rates up to the age of 80. The incidence of >or= 50% symptomatic stenosis increased steeply with age, particularly in those aged >or= 80. Compared with investigations in patients in the Oxford vascular study, the rates of carotid imaging (relative rate 0.36, 95% confidence interval 0.28 to 0.46, P < 0.0001), diagnosis of >or= 50% symptomatic stenosis (0.33, 0.16 to 0.69, P = 0.004), and carotid endarterectomy (0.19, 0.06 to 0.63, P = 0.007) in this age group in routine clinical practice were all substantially lower.

CONCLUSIONS

Incidence of symptomatic carotid stenosis increases steeply with age, but, despite good evidence of major benefit from endarterectomy in elderly patients and a willingness to have surgery, there is substantial underinvestigation in routine clinical practice in patients aged >or= 80 with transient ischaemic attack or ischaemic stroke.

Secondary Prevention of Stroke in Patients with Atrial Fibrillation: Factors Influencing the Prescription of Oral Anticoagulation at Discharge

BACKGROUND

Oral anticoagulation (OAC) is the only treatment that has shown a significant benefit to reduce the risk of recurrence in patients with ischemic stroke and nonvalvular atrial fibrillation (NVAF). However, OAC is still underused, even at discharge from neurological centers. The objective of this study was to identify the reasons underlying the prescription of OAC at discharge after an ischemic stroke in patients with NVAF.

METHODS

We investigated the reasons why ischemic stroke patients with NVAF were not treated with OAC at discharge from 40 centers located in 5 European countries (Austria, Belgium, France, Italy, and Portugal).

RESULTS

Of 320 ischemic stroke survivors at discharge, 186 (58.1%) received OAC, while 260 (81.3%) patients were theoretically eligible according to guidelines and the absence of contraindications. There were significant differences between countries and the logistic regression analysis found being already under OAC before stroke, having no leukoaraiosis, having no potential contraindication, being younger than 75 years, being married and suffering from angina pectoris as independent predictors of being discharged under OAC.

CONCLUSION

This study suggests that besides patient-related factors, the prescription of OAC is also significantly influenced by the social environment and national practices.

Not All Patients With Atrial Fibrillation–Associated Ischemic Stroke Can Be Started on Anticoagulant Therapy

Background and Purpose— Ischemic stroke patients in atrial fibrillation (AF) have a 10% to 20% risk of recurrent stroke. Warfarin reduces this risk by two thirds. However, warfarin is underutilized in this patient group. We performed a prospective study to determine the reasons why warfarin is not started in these patients.

Methods— All patients with AF-associated ischemic stroke over a 12-month period were identified. Demographic and other data, including whether warfarin was commenced or recommended at discharge, and if not why not, were recorded.

Results— Ninety-three of 412 (23%) ischemic stroke patients had paroxysmal or permanent AF. Of these patients, 17 (18%) died, 48 (52%) were discharged home, and 28 (30%) were discharged to institutional care. Only 13 of 64 (20%) patients with known AF were taking warfarin at stroke onset. Warfarin was started (or recommended) in 35 of 76 (46%) survivors. Of those not commenced on warfarin, 32 (78%) were dependent ( P <0.001) and 23 (56%) were discharged to institutional care ( P <0.001). Warfarin was not started because of severe disability and frailty in 13 (32%), risk of falls in 12 (30%), and limited life expectancy in 4 (10%).

Conclusions— In this cohort of patients with AF, warfarin was primarily underutilized before stroke onset, and it was too late to use anticoagulation, in approximately half, once a stroke had occurred. The decision to start or continue anticoagulation requires clinical judgment and should be made on a case by case basis after a complete risk benefit assessment.

Activation of cerebral endothelium is required for mononuclear cell recruitment in a novel in vitro model of brain inflammation

Brain inflammation is a common event in the pathogenesis of several neurological diseases. It is unknown whether leukocyte/endothelium interactions are sufficient to promote homing of blood-borne cells into the brain compartment. The role of mononuclear cells and endothelium was analyzed in a new experimental model, the isolated guinea-pig brain maintained in vitro by arterial perfusion. This preparation allows one to investigate early steps of brain inflammation that are impracticable in vivo. We demonstrate by confocal microscopy analysis that in vitro co-perfusion of pro-inflammatory agents and pre-activated fluorescent mononuclear cells induced endothelial expression of selectins and intracellular adhesion molecule-1 in correspondence of arrested mononuclear cells, and correlates with a moderate increase in blood-brain barrier permeability. Separate perfusion of pro-inflammatory agents and mononuclear cells induced neither mononuclear cell adhesion nor adhesion molecule expression. We demonstrate that co-activation of mononuclear cells and cerebral endothelium is an essential requirement for cell arrest and adhesion in the early stages of experimental cerebral inflammation.

Optimizing the Use of Antithrombotic Therapy for Atrial Fibrillation in Older People: A Pharmacist-Led Multidisciplinary Intervention

OBJECTIVES

To develop, implement, and evaluate a pharmacist-led multidisciplinary intervention in a hospital setting that would optimize antithrombotic use in elderly atrial fibrillation patients. The hypothesis that there would be an increase in the proportion of patients receiving antithrombotic therapy at discharge was tested.

DESIGN

Evidence-based algorithms were developed to define the criteria (stroke risk vs contraindications) by which an elderly patient's requirement for antithrombotic therapy was assessed.

SETTING

A major Sydney teaching hospital.

PARTICIPANTS

Two hundred eighteen consecutively admitted elderly patients (mean age 85.2) were recruited over a 6-month period.

INTERVENTION

A pharmacist-coordinated multidisciplinary review process was implemented to coordinate risk assessments and subsequently recommend appropriate antithrombotic therapy, as per the algorithms.

MEASUREMENTS

The proportion of patients receiving antithrombotic therapy was assessed on admission (preintervention), at discharge (postintervention), and postdischarge (follow-up at 3 and 6 months).

RESULTS

As a result of the intervention, 78 patients (35.8%) required changes to their existing antithrombotic therapy. Of these changes, 60 (76.9%) were "upgrades" to more-effective treatment options (e.g., from no therapy to any agent or from aspirin to warfarin). The remaining 18 (23.1%) changes were "downgrades" to less-effective, albeit safer, options. Despite a significant increase in anti thrombotic use overall (59.6% vs 81.2%, P<.001), fewer patients received warfarin postintervention, after having been assessed as inappropriate candidates (20.7% vs 17.4%, P=.39).

CONCLUSION

A pharmacist-led multidisciplinary process was successfully developed and implemented within the hospital setting to increase overall antithrombotic use. Having addressed some of the known barriers and limitations to warfarin use, these algorithms may allow allied health workers, patients, and clinicians to work collaboratively to achieve optimal and, importantly, appropriate (i.e., safe and effective) antithrombotic use in at-risk elderly patients.

New treatment options for stroke prevention in atrial fibrillation

Atrial fibrillation (AF) is the most common arrhythmia requiring treatment. Its most devastating consequence is thromboembolic stroke. Therapy with warfarin is indicated in most patients, as it has been shown conclusively to reduce the risk of stroke. Aspirin is an inferior alternative except in certain low-risk patients or for patients with an absolute contraindication to warfarin. Guidelines have been published for the administration of antithrombotic therapy in AF, but many patients who are candidates for anticoagulation do not receive this therapy. Even as this therapy is under-utilized, the indication for anticoagulation is expanding. Indefinite continuation of anticoagulation should be considered in higher-risk patients despite the appearance that sinus rhythm has been restored because asymptomatic (or silent) AF occurs frequently. Newer agents that offer substantial benefit over warfarin are being developed and would enhance compliance with anticoagulation in AF if these novel therapies prove to be safe and equivalent to warfarin in efficacy.

Prognostic implications of warfarin cessation after major trauma: a population-based cohort analysis

BACKGROUND

Warfarin therapy is often withheld from elderly patients who fall or otherwise experience injury because of concerns regarding the long-term risk of hemorrhage in these individuals. We studied whether stopping warfarin after trauma is associated with a higher risk of subsequent adverse cardiovascular events.

METHODS AND RESULTS

We conducted a retrospective, population-based, cohort study using linked administrative databases in the province of Ontario, Canada for the years 1992 to 2001. A total of 8450 elderly patients (age >65 years) who survived an incident of major trauma and were receiving warfarin before injury were followed up for a mean of 3.3 years. During the 6-month interval after trauma, 1827 (22%) patients discontinued warfarin, whereas 6623 (78%) patients continued warfarin. Warfarin cessation was not associated with an increased risk of subsequent stroke (hazard ratio [HR] 0.99, 95% CI 0.82 to 1.21) or myocardial infarction (HR 0.94, 95% CI 0.74 to 1.20) but was associated with a lower risk of major hemorrhage (HR 0.69, 95% CI 0.54 to 0.88) and a higher risk of venous thromboembolism (HR 1.59, 95% CI 1.07 to 2.36). Adjustment for baseline demographics, stroke risk factors, other comorbidities, and characteristics of the trauma did not materially change these findings. On-treatment analyses yielded similar results.

CONCLUSIONS

Cessation of warfarin in elderly patients after major trauma was not associated with an increased risk of arterial thrombotic events but was associated with a significantly increased risk of venous thromboembolism.

Quality of Anticoagulation Control and Costs of Monitoring Warfarin Therapy among Patients with Atrial Fibrillation in Clinic Settings: A Multi-Site Managed-Care Study

BACKGROUND:

Warfarin is recommended for prevention of stroke in patients with atrial fibrillation who are at moderate or high risk, but requires intensive management to achieve safe and optimal anticoagulation control. Anticoagulation clinics are often used to administer warfarin therapy more effectively.

OBJECTIVE:

To collect data from multiple sites and assess the quality and costs associated with anticoagulation clinic services.

METHODS:

A random sample of 600 adults with chronic nonvalvular atrial fibrillation (CNVAF) receiving warfarin was selected from anticoagulation clinics affiliated with 3 health plans. Patients were identified between 1996 and 1998 and followed for up to one year. We assessed the proportion of time that international normalized ratio (INR) values were within the recommended range (2.0–3.0) and the costs of anticoagulation clinic care.

RESULTS:

Patients had an average of 18 clinic contacts over a mean duration of follow-up of 10.5 months. On average, patients were within the recommended INR range 62% of this time, with 25% of days below range and 13% above range. The mean per-patient cost of warfarin monitoring over the follow-up period averaged $261 at site A, $305 at site B, and $205 at site C (in 2003 US$). Mean costs for patients treated for one full year were $288, $339, and $216, respectively.

CONCLUSIONS:

In 3 geographically diverse health plans, anticoagulation clinics provided a generally higher quality of control than previously reported in other observational studies. This study highlights the costs of obtaining this level of control.

The use of warfarin in veterans with atrial fibrillation

Background

Warfarin therapy is effective for the prevention of stroke in patients with atrial fibrillation. However, warfarin therapy is underutilized even among ideal anticoagulation candidates. The purpose of this study was to examine the use of warfarin in both inpatients and outpatients with atrial fibrillation within a Veterans Affairs (VA) hospital system.

Methods

This retrospective medical record review included outpatients and inpatients with atrial fibrillation. The outpatient cohort included all patients seen in the outpatient clinics of the VA Connecticut Healthcare System during June 2000 with a diagnosis of atrial fibrillation. The inpatient cohort included all patients discharged from the VA Connecticut Healthcare System West Haven Medical Center with a diagnosis of atrial fibrillation during October 1999 – March 2000. The outcome measure was the rate of warfarin prescription in patients with atrial fibrillation.

Results

A total of 538 outpatients had a diagnosis of atrial fibrillation and 73 of these had a documented contraindication to anticoagulation. Among the 465 eligible outpatients, 455 (98%) were prescribed warfarin. For the inpatients, a total of 212 individual patients were discharged with a diagnosis of atrial fibrillation and 97 were not eligible for warfarin therapy. Among the 115 eligible inpatients, 106 (92%) were discharged on warfarin.

Conclusions

Ideal anticoagulation candidates with atrial fibrillation are being prescribed warfarin at very high rates within one VA system, in both the inpatient and outpatient settings; we found warfarin use within our VA was much higher than that observed for Medicare beneficiaries in our state.

The Role of Oral Direct Thrombin Inhibitors in Atrial Fibrillation

Atrial fibrillation is a common rhythm disturbance; its most significant adverse events are ischemic stroke and systemic arterial occlusion. Oral anticoagulation with warfarin is an effective therapy for stroke prevention but remains underused due to numerous complications and barriers. Ximelagatran, an oral direct thrombin inhibitor, may become an alternative strategy for clinicians. This agent was developed to overcome many of the limitations associated with warfarin. Its consistent antithrombotic effect and wide therapeutic index allow fixed dosing without the need for routine coagulation monitoring, and without concerns related to drug, food, and disease state interactions. Ximelagatran has been investigated in patients with atrial fibrillation and has been as effective as warfarin for stroke prevention.

The increasing need for anticoagulant therapy to prevent stroke in patients with atrial fibrillation

Ischemic stroke, a major complication of atrial fibrillation (AF), is believed to result from atrial thrombus formation caused by ineffective atrial contraction. Oral anticoagulant therapy effectively reduces the risk of ischemic stroke in patients with AF; this therapy is recommended for patients with any frequency or duration of AF and other risk factors for stroke, such as increased age (>75 years), hypertension, prior stroke, left ventricular dysfunction, diabetes, or heart failure. Recently published data comparing rate-control and rhythm-control strategies in AF emphasized the importance of maintaining an international normalized ratio higher than 2.0 during warfarin therapy and the need for continuing anticoagulant therapy to prevent stroke in high-risk patients, even if the strategy is rhythm control. Hemorrhagic complications can be minimized by stringent control of the international normalized ratio (particularly in elderly patients) and appropriate therapy for comorbidities such as hypertension, gastric ulcer, and early-stage cancers. Undertreatment of patients with AF is a continuing problem, particularly in the elderly population. Patients perceived as likely to be noncompliant, such as the functionally impaired, are less likely to receive warfarin therapy. However, stroke prevention with anticoagulants is cost-effective and improves quality of life, despite the challenges of maintaining appropriate anticoagulation with monitoring and warfarin dose titration. New medications in development with more predictable dosing and fewer drug-drug interactions may reduce the complexities of achieving optimal anticoagulation and increase the practicality of long-term anticoagulant therapy for patients with AF at risk of stroke.

Physicians' attitudes toward anticoagulant therapy in patients with chronic atrial fibrillation

INTRODUCTION

Although many clinical trials have demonstrated that anticoagulant therapy substantially reduces the risk of ischemic stroke in patients with atrial fibrillation (AF), some physicians are reluctant to use anticoagulants. We investigated attitudes of physicians in Japan toward anticoagulant therapy in chronic AF patients.

METHODS

We conducted a survey at the annual meeting of the Japanese Society of General Medicine. We presented subject physicians with 8 vignettes of chronic AF patients and requested that they indicate their most favored choice of therapy from among 6 strategies including warfarin and aspirin.

RESULTS

We distributed 209 questionnaires and received 139 replies (67% response rate). For all 8 vignettes presented, only 26% of the respondents preferred to use anticoagulant therapy in AF patients. Longer clinical experiences and responsibility at a teaching hospital were associated with negative attitude toward anticoagulant therapy, while experience of preventive therapy in patients with thromboembolism due to AF and strong influence of clinical trials of anticoagulant prophylaxis on their practice were associated with positive attitude toward the therapy. Among patient characteristics in the vignettes, a risk of thromboembolism was positively associated with preference for anticoagulant therapy, but an advanced age and a risk of bleeding complications were negatively associated with the preference for the therapy.

CONCLUSIONS

The physicians in Japan in this survey, especially those with longer clinical experiences or responsibility at a teaching hospital, have a negative attitude toward anticoagulant therapy in chronic AF patients. An advanced age and a risk of bleeding complications of patients are deterrent factors to the use of anticoagulant therapy.

Incidence of chronic atrial fibrillation in general practice and its treatment pattern

The object of this article was to estimate the incidence rate of chronic atrial fibrillation (AF) in a general practice setting, to identify factors predisposing to its occurrence, and to describe treatment patterns in the year following the diagnosis. The method used was a population-based cohort study using the General Practice Research Database (GPRD) in the UK. We identified patients aged 40-89 years with a first ever recorded diagnosis of AF. The diagnosis was validated through a questionnaire sent to the general practitioners. A nested case-control analysis was performed to assess risk factors for AF using 1,035 confirmed incident cases of chronic AF and a random sample of 5,000 controls from the original source population. The incidence rate of chronic AF was 1.7 per 1,000 person-years, and increased markedly with age. The age adjusted rate ratio among males was 1.4 (95% CI 1.2-1.6). The major risk factors were age, high BMI, excessive alcohol consumption, and prior cardiovascular comorbidity, in particular, valvular heart disease and heart failure. Digoxin was used in close to 70% of the patients, and close to 15% did not receive any antiarrhythmic treatment. Close to 40% did not receive either warfarin or aspirin in the 3 months period after the diagnosis. Among the potential candidates for anticoagulation only 22% of those aged 70 years or older were prescribed warfarin in comparison to 49% among patients aged 40-69 years. Chronic AF is a disease of the elderly, with women presenting a lower incidence rate than men specially in young age. Age, weight, excessive alcohol consumption, and cardiovascular morbidity were the main independent risk factors for AF. Less than half of patients with chronic AF and no contraindications for anticoagulation received warfarin within the first trimester after the diagnosis.

Atrial fibrillation and antithrombotic treatment in Italian hospitalized patients: a prospective, observational study

BACKGROUND

We studied the prevalence of atrial fibrillation within a large Italian inpatient population, and evaluated the use of antithrombotic therapy among these individuals.

METHODS

A prospective cross sectional study (Phase 1) with a 1-year follow-up period (Phase 2) was conducted at a single Italian centre. During Phase 1, we conducted a chart review of all inpatients on 5 separate days, each 1 month apart, between January and May 1999. During Phase 2, at 1-year of follow-up, patients or their families were contacted to document the occurrence of new clinical events, as well as current antithrombotic therapy use.

RESULTS

A total of 3121 patient charts were reviewed. The prevalence of atrial fibrillation was 7.2%. Of these 224 patients, 21.3% were on oral anticoagulants, 29.7% on antiplatelets, while 49% received neither. Patients on oral anticoagulants were significantly younger (mean age 72.3 years) than those on antiplatelets (mean age 80.6 years; p<0.001) or neither therapy (mean age 80.7 years; p<0.001). At 1 year follow up, an acute ischaemic stroke occurred among 7.4% of the 121 contacted patients. Among patients with chronic atrial fibrillation [98], 25.5% were receiving an oral anticoagulant.

CONCLUSIONS

Despite clear evidence from clinical trials, oral anticoagulants are significantly underused among patients with chronic atrial fibrillation. Methods should be developed to improve both physician and patient knowledge about the overall benefits of anti-thrombotic therapy among these individuals.

Is warfarin really underused in patients with atrial fibrillation?

CONTEXT

There is agreement that warfarin decreases stroke risk in patients with atrial fibrillation (AF), but prior studies suggest that warfarin is markedly underused, for unclear reasons.

OBJECTIVE

To determine if warfarin is underused in the treatment of patients with atrial fibrillation.

DESIGN

Cross-sectional.

SETTING

Tertiary care VA hospital.

PATIENTS

All patients with a hospital or outpatient diagnosis of AF between 10/1/95 and 5/31/98.

DATA COLLECTION

One or more physician investigators reviewed pertinent records for each patient. When any of the 3 investigators thought warfarin might be indicated, the patient's primary care provider completed a survey regarding why warfarin was not used.

RESULTS

Of 1,289 AF patients, 844 (65%) had filled at least 1 warfarin prescription. Of the 445 remaining, 19 had died, 5 had inadequate medical records, and 54 received warfarin elsewhere, leaving 367 patients. Of these, 160 had no documented AF, 53 had only a history of AF, and 49 had only transient AF. Of the remaining 105 patients, 17 refused warfarin therapy and 72 had documented contraindications to warfarin use including bleeding risk or history, fall risk, alcohol abuse, or other compliance problems. The reasons for not using warfarin among the 16 patients remaining included provider oversight (n = 4) and various reasons suggesting provider knowledge deficits.

CONCLUSION

In contrast to prior studies that suggested that warfarin is markedly underused, we found that few patients with AF and no contraindication to anticoagulation were not receiving warfarin. We believe that differing study methodologies, including the use of physician review and provider survey, may explain our markedly different rate of warfarin underutilization, although local institutional factors cannot be excluded. The findings suggest that primary providers may be far more compliant with the standard of care for patients with atrial fibrillation than previously believed.

Anticoagulation in the elderly

Oral anticoagulation therapy has demonstrated benefit in the treatment and prevention of a variety of thromboembolic disorders. Most individuals who receive oral anticoagulant therapy are elderly patients with nonvalvular atrial fibrillation and acute or recurrent venous thromboembolism. Anticoagulation in elderly patients poses unique challenges for the practicing clinician because they are simultaneously at higher risk for recurrent thromboembolism and major bleeding, including catastrophic intracranial hemorrhage. The pharmacology of warfarin in the elderly is reviewed, including important drug interactions and current dosing recommendations for elderly patients. Evidence of the benefits and risks of oral anticoagulation therapy are reviewed for patients with atrial fibrillation and venous thromboembolism. This information should enable practitioners to better assess the relative risks and benefit of oral anticoagulation therapy to guide treatment decisions in the elderly.

Anticoagulants or antiplatelet therapy for non-rheumatic atrial fibrillation and flutter

BACKGROUND

Atrial fibrillation (AF) carries a high risk of stroke and other thromboembolic events. Appropriate use of drugs to prevent thromboembolism in patients with AF involves comparing the patient's risk of stroke to the risk of hemorrhage from medication use.

OBJECTIVES

To quantify risk of stroke, major hemorrhage and death from using medications that have been rigorously evaluated for prevention of thromboembolism in AF.

SEARCH STRATEGY

Articles were identified through the Cochrane Collaboration's CENTRAL database and MEDLINE until December 1999.

SELECTION CRITERIA

Included Randomized controlled trials of drugs to prevent thromboembolism in adults with non-postoperative AF. Excluded RCTS of patients with rheumatic valvular disease.

DATA COLLECTION AND ANALYSIS

Data were abstracted by two reviewers. Odds ratios from all qualitatively similar studies were combined, with weighting by study size, to yield aggregate odds ratios for stroke, major hemorrhage, and death for each drug.

MAIN RESULTS

Fourteen articles were included in this review. Warfarin was more efficacious than placebo for primary stroke prevention [aggregate odds ratio (OR) of stroke=0.30 [95% Confidence Interval (C.I.) 0.19,0.48]], with moderate evidence of more major bleeding [ OR= 1.90 [95% C.I. 0.89,4.04].]. Aspirin was inconclusively more efficacious than placebo for stroke prevention [OR=0.68 [95% C.I. 0.29,1.57]], with inconclusive evidence regarding more major bleeds [OR=0.81[95% C.I. 0.37,1.78]]. For primary prevention, assuming a baseline risk of 45 strokes per 1000 patient-years, warfarin could prevent 30 strokes at the expense of only 6 additional major bleeds. Aspirin could prevent 17 strokes, without increasing major hemorrhage. In direct comparison, there was moderate evidence for fewer strokes among patients on warfarin than on aspirin [aggregate OR=0.64[95% C.I. 0.43,0.96]], with only suggestive evidence for more major hemorrhage [OR =1.58 [95% C.I. 0.76,3.27]]. However, in younger patients, with a mean age of 65 years, the absolute reduction in stroke rate with warfarin compared to aspirin was low (5.5 per 1000 person-years) compared to an older group (15 per 1000 person-years). Low-dose warfarin or low-dose warfarin with aspirin was less efficacious for stroke prevention than adjusted-dose warfarin.

REVIEWER'S CONCLUSIONS

The evidence strongly supports warfarin in AF for patients at average or greater risk of stroke, although clearly there is a risk of hemorrhage. Although not definitively supported by the evidence, aspirin may prove to be useful for stroke prevention in sub-groups with a low risk of stroke, with less risk of hemorrhage than with warfarin. Further studies are needed of low- molecular weight heparin and aspirin in lower risk patients.

Development of a decision aid for atrial fibrillation who are considering antithrombotic therapy

With patients demanding a greater role in the clinical decision-making process, many researchers are developing and disseminating decision aids for various medical conditions. In this article, we outline the essential elements in the development and evaluation of a decision aid to help patients with atrial fibrillation choose, in consultation with their physicians, appropriate antithrombotic therapy (warfarin, aspirin, or no therapy) to prevent stroke. We also outline possible future directions regarding the implementation and evaluation of this decision aid. This information should enable clinicians to better understand the role that decision aids may have in their interactions with patients.

Cost effectiveness of therapies for atrial fibrillation. A review

Atrial fibrillation is the most common supraventricular tachyarrhythmia encountered in clinical practice, affecting over 5% of persons over the age of 65 years. A common pathophysiological mechanism for arrhythmia development is atrial distention and fibrosis induced by hypertension, coronary artery disease or ventricular dysfunction. Less frequently, atrial fibrillation is caused by mitral stenosis or other provocative factors such as thyrotoxicosis, pericarditis or alcohol intoxication. Depending on the extent of associated cardiovascular disease, atrial fibrillation may produce haemodynamic compromise, or symptoms such as palpitations, fatigue, chest pain or dyspnoea. Arrhythmia-induced atrial stasis can precipitate clot formation and the potential for subsequent thromboembolism. Comprehensive management of atrial fibrillation requires a multifaceted approach directed at controlling symptoms, protecting the patient from ischaemic stroke or peripheral embolism and possible conversion to or maintenance of sinus rhythm. Numerous randomised trials have demonstrated the efficacy of warfarin--and less so aspirin (acetylsalicylic acid)--in reducing the risk of embolic events. Furthermore, therapeutic strategies exist that can favourably modify symptoms by restoring and maintaining sinus rhythm with cardioversion and antiarrhythmic prophylaxis. However, the risks and benefits of various treatments is highly dependent on patient-specific features, emphasising the need for an individualised approach. This article reviews the findings of cost-effectiveness studies published over the past decade that have evaluated different components of treatment strategies for atrial fibrillation. These studies demonstrate the economic attractiveness of acute management options, long term warfarin prophylaxis, telemetry-guided initiation of antiarrhythmic therapy, approaches to restore and maintain sinus rhythm, and the potential role of transoesophageal echocardiographic screening for atrial thrombus prior to pharmacological or electrical cardioversion. Further, we discuss the merits and limitations of the cost-effectiveness analyses in the context of overall treatment strategies. Finally, we identify areas that will require additional research to achieve the goal of effective and economically efficient management of atrial fibrillation.