Rivaroxaban versus aspirin for secondary prevention of ischaemic stroke in patients with cancer: a subgroup analysis of the NAVIGATE ESUS randomized trial

BACKGROUND AND PURPOSE

Cancer is a frequent finding in ischaemic stroke patients. The frequency of cancer amongst participants in the NAVIGATE ESUS randomized trial and the distribution of outcome events during treatment with aspirin and rivaroxaban were investigated.

METHODS

Trial participation required a recent embolic stroke of undetermined source. Patients' history of cancer was recorded at the time of study entry. During a mean follow-up of 11 months, the effects of aspirin and rivaroxaban treatment on recurrent ischaemic stroke, major bleeding and all-cause mortality were compared between patients with cancer and patients without cancer.

RESULTS

Amongst 7213 randomized patients, 543 (7.5%) had cancer. Of all patients, 3609 were randomized to rivaroxaban [254 (7.0%) with cancer] and 3604 patients to aspirin [289 (8.0%) with cancer]. The annual rate of recurrent ischaemic stroke was 4.5% in non-cancer patients in the rivaroxaban arm and 4.6% in the aspirin arm [hazard ratio (HR) 0.98, 95% confidence interval (CI) 0.78-1.24]. In cancer patients, the rate of recurrent ischaemic stroke was 7.7% in the rivaroxaban arm and 5.4% in the aspirin arm (HR 1.43, 95% CI 0.71-2.87). Amongst cancer patients, the annual rate of major bleeds was non-significantly higher for rivaroxaban than aspirin (2.9% vs. 1.1%; HR 2.57, 95% CI 0.67-9.96; P for interaction 0.95). All-cause mortality was similar in both groups.

CONCLUSIONS

Our exploratory analyses show that patients with embolic stroke of undetermined source and a history of cancer had similar rates of recurrent ischaemic strokes and all-cause mortality during aspirin and rivaroxaban treatments and that aspirin appeared safer than rivaroxaban in cancer patients regarding major bleeds. www.clinicaltrials.gov (NCT02313909).

Blood-pressure targets in patients with recent lacunar stroke: the SPS3 randomised trial

BACKGROUND

Lowering of blood pressure prevents stroke but optimum target levels to prevent recurrent stroke are unknown. We investigated the effects of different blood-pressure targets on the rate of recurrent stroke in patients with recent lacunar stroke.

METHODS

In this randomised open-label trial, eligible patients lived in North America, Latin America, and Spain and had recent, MRI-defined symptomatic lacunar infarctions. Patients were recruited between March, 2003, and April, 2011, and randomly assigned, according to a two-by-two multifactorial design, to a systolic-blood-pressure target of 130-149 mm Hg or less than 130 mm Hg. The primary endpoint was reduction in all stroke (including ischaemic strokes and intracranial haemorrhages). Analysis was done by intention to treat. This study is registered with ClinicalTrials.gov, number NCT 00059306.

FINDINGS

3020 enrolled patients, 1519 in the higher-target group and 1501 in the lower-target group, were followed up for a mean of 3·7 (SD 2·0) years. Mean age was 63 (SD 11) years. After 1 year, mean systolic blood pressure was 138 mm Hg (95% CI 137-139) in the higher-target group and 127 mm Hg (95% CI 126-128) in the lower-target group. Non-significant rate reductions were seen for all stroke (hazard ratio 0·81, 95% CI 0·64-1·03, p=0·08), disabling or fatal stroke (0·81, 0·53-1·23, p=0·32), and the composite outcome of myocardial infarction or vascular death (0·84, 0·68-1·04, p=0·32) with the lower target. The rate of intracerebral haemorrhage was reduced significantly (0·37, 0·15-0·95, p=0·03). Treatment-related serious adverse events were infrequent.

INTERPRETATION

Although the reduction in stroke was not significant, our results support that in patients with recent lacunar stroke, the use of a systolic-blood-pressure target of less than 130 mm Hg is likely to be beneficial.

FUNDING

National Institutes of Health-National Institute of Neurological Disorders and Stroke (NIH-NINDS).

Albuminuria and the risk of incident stroke and stroke types in older adults

BACKGROUND

The kidney biomarker that best reflects risk of stroke is unknown. We sought to evaluate the association of stroke with 3 kidney biomarkers: albuminuria, cystatin C, and glomerular filtration rate.

METHODS

These 3 biomarkers were determined in 3,287 participants without history of stroke from the Cardiovascular Health Study, a longitudinal cohort study of men and women age 65 years and older from 4 US communities. The biomarkers were albuminuria ascertained using urinary albumin-to-creatinine ratio (UACR) from morning spot urine, creatinine-based estimated glomerular filtration rate (eGFR), and cystatin C. Outcomes were incident stroke (any, ischemic, or hemorrhagic) during follow-up between 1996 and 2006.

RESULTS

A total of 390 participants had an incident stroke: 81% ischemic, 12% hemorrhagic, and 7% unclassified. In adjusted Cox regression models, UACR was more strongly related to any stroke, ischemic stroke, and hemorrhagic stroke than eGFR and cystatin C. The hazard ratio (HR) of any stroke comparing the top to bottom quintile of UACR was 2.10 (95% confidence interval [CI] 1.47-3.00), while HR for eGFR was 1.29 (95% CI 0.91-1.84) and for cystatin C was 1.22 (95% CI 0.85-1.74). When considering clinically relevant categories, elevated UACR was associated with increased hazard of any stroke and ischemic stroke regardless of eGFR or cystatin C categories.

CONCLUSIONS

UACR was the kidney biomarker most strongly associated with risk of incident stroke. Results in this elderly cohort may not be applicable to younger populations. These findings suggest that measures of glomerular filtration and permeability have differential effects on stroke risk.

Applicability of NINDS-sponsored studies to community-based physician involvement

Background: The National Institute of Neurological Disorders and Stroke (NINDS) Clinical Trials Group established the Clinical Research Collaboration (CRC) Project in 2005 to increase community-based physician involvement in NINDS-sponsored research.

Methods: We assessed a random sample of 112 of the more than 1,000 current NINDS-sponsored clinical research studies to determine which could involve community physicians in enrollment or follow-up. Scoring factors were based on the premise that participation is feasible for noninvasive studies with simple screening, and follow-up criteria and visit frequency consistent with usual care. Scored studies included 26 Phase III, 31 Phase I/II, and 55 nonclinical trials.

Results: Overall, 41% of the sampled research studies were considered conducive to community physician participation that exceeds referral only; 21% with participation in all study activities and 20% with ability to provide some follow-up. Specialized neuropsychological or neurologic scale testing was judged to exclude community physician participation in 16% of studies.

Conclusion: Many National Institute of Neurological Disorders and Stroke studies are available in which community-based physicians could participate. Involving community physicians may increase efficiency of completing clinical research and encourage application of research findings in community practices.

A hand research fellowship training programme

There are currently 68 hand surgery fellowship programmes known to the authors in the United States and many more throughout the world. To our knowledge, there are no hand fellowships which focus on research. Such a hand surgery research fellowship is being developed to provide this training. This paper outlines the goals and objectives of the intended 2 year training programme and includes a description of the fellowship. The first year would be mostly committed to learning research methods and the second would be a clinical hand fellowship. This will combine clinical expertise in hand surgery, practical research experience and formal research training. Hand researchers would learn research methods, develop innovative research ideas and begin an active research and academic career.

Effects of congestive heart failure on plasma von Willebrand factor and soluble P-selectin concentrations in patients with non-valvar atrial fibrillation

OBJECTIVE

To examine further the relations of plasma von Willebrand factor (vWf, an index of endothelial damage and dysfunction) and soluble P-selectin (sP-sel, an index of platelet activation) concentrations to the presence and onset of clinical congestive heart failure (CHF) and the degree of left ventricular (LV) dysfunction in patients taking part in the SPAF (stroke prevention in atrial fibrillation) study.

METHODS

Plasma concentrations of vWf and sP-sel were measured by enzyme linked immunosorbent assay (ELISA) in 1321 participants in the SPAF III study and related to the presence and onset of clinical CHF, as well as echocardiographic findings. Of the 1321 patients with atrial fibrillation (AF), 331 (25%) had a documented history of clinical heart failure, of which 168 cases were related to a new or recurrent episode of acute decompensated heart failure occurring within the preceding three months.

RESULTS

Mean plasma vWf was higher among patients with AF and CHF (154 (29) v 144 (31) IU/dl, p < 0.001), particularly those with acute or recent decompensated symptoms. Patients with severe LV dysfunction on two dimensional echocardiography and low fractional shortening also had significantly higher vWf concentrations than those with no LV dysfunction. CHF patients with clinical features--with (156 (28) IU/dl) and without (152 (31) IU/dl) LV dysfunction--also had higher mean vWf concentrations than patients with asymptomatic LV dysfunction (146 (31) IU/dl, p < 0.001). The presence of mitral regurgitation in CHF was associated with lower vWf concentrations. Plasma sP-sel concentrations were not affected by presence, onset, or severity of heart failure.

CONCLUSIONS

CHF may contribute to hypercoagulability and thrombotic risk in AF through increased endothelial damage and dysfunction. Patients with acute or recent decompensated features have the highest degree of endothelial damage and dysfunction. The presence of CHF clinical features was an important determinant of plasma vWf concentrations.

Neuroprotective agents for clinical trials in Parkinson's disease: a systematic assessment

BACKGROUND

Current therapies for PD ameliorate symptoms in the early phases of disease but become less effective over time, as the underlying disease progresses. Therapies that slow the progression of PD are needed. However, there have been relatively few clinical trials aimed at demonstrating neuroprotection. The authors sought to identify potential neuroprotective agents for testing in clinical trials.

METHODS

First a broad array of compounds were identified by working with clinicians and researchers in academics and industry. Specific criteria were drafted for drug evaluation, including scientific rationale, blood-brain barrier penetration, safety and tolerability, and evidence of efficacy in animal models or humans. Agents were prioritized based on these criteria.

RESULTS

The authors identified 59 potential neuroprotective compounds, proposed by 42 clinicians and scientists from 13 countries. After systematic reviews using the specified criteria they found 12 compounds to be attractive candidates for further clinical trials in PD.

CONCLUSIONS

Several potential neuroprotective compounds, representing a wide range of mechanisms, are available and merit further investigation in PD.

Cerebral hemorrhage after intra-arterial thrombolysis for ischemic stroke: the PROACT II trial

OBJECTIVE

To analyze the frequency, clinical characteristics, and predictors of symptomatic intracerebral hemorrhage (ICH) after intraarterial (IA) thrombolysis with recombinant pro-urokinase (r-proUK) in acute ischemic stroke.

METHOD

The authors conducted an exploratory analysis of symptomatic ICH from a randomized, controlled clinical trial of IA thrombolysis with r-proUK for patients with angiographically documented occlusion of the middle cerebral artery within 6 hours from stroke onset. Patients (n = 180) were randomized in a ratio of 2:1 to either 9 mg IA r-proUK over 120 minutes plus IV fixed-dose heparin or IV fixed-dose heparin alone. As opposed to intention to treat, this analysis was based on "treatment received" and includes 110 patients given r-proUK and 64 who did not receive any thrombolytic agent. The remaining six patients received out-of-protocol urokinase and were excluded from analysis. The authors analyzed centrally adjudicated ICH with associated neurologic deterioration (increase in NIH Stroke Scale [NIHSS] score of > or =4 points) within 36 hours of treatment initiation.

RESULTS

Symptomatic ICH occurred in 12 of 110 patients (10.9%) treated with r-proUK and in two of 64 (3.1%) receiving heparin alone. ICH symptoms in r-proUK-treated patients occurred at a mean of 10.2 +/- 7.4 hours after the start of treatment. Mortality after symptomatic ICH was 83% (10/12 patients). Only blood glucose was significantly associated with symptomatic ICH in r-proUK-treated patients based on univariate analyses of 24 variables: patients with baseline glucose >200 mg/dL experienced a 36% risk of symptomatic ICH compared with 9% for those with < or =200 mg/dL (p = 0.022; relative risk, 4.2; 95% CI, 1.04 to 11.7).

CONCLUSIONS

Symptomatic ICH after IA thrombolysis with r-proUK for acute ischemic stroke occurs early after treatment and has high mortality. The risk of symptomatic ICH may be increased in patients with a blood glucose >200 mg/dL at stroke onset.

Differences in treatment preferences between persons who enrol and do not enrol in a clinical trial

OBJECTIVE

To quantitatively compare preferences for treatment between persons who enrolled in a randomized controlled trial (RCT) and those who were eligible but chose not to enrol.

INTERVENTIONS

Participants' thresholds for treatment were determined using a probability trade-off technique. Pertinent health states were described. If not taking Aspirin, the probabilities of stroke, myocardial infarction (MI), and major bleeding were given. Given the risks and benefits of chronic Aspirin therapy, a systematic approach was used to determine patients' thresholds for treatment (the smallest reduction in stroke or MI risk of which patients were willing to take Aspirin).

RESULTS

Of 54 participants, 42 enrolled in the RCT, and 12 did not. Compared with persons who enrolled, those who did not enrol required significantly greater increments in treatment benefit to be willing to take Aspirin.

CONCLUSIONS

This study shows differences in thresholds for treatment between persons who enrolled in a clinical trial and those who chose not to. Such attitudinal differences may lead to difficulty in the interpretation of clinical trials, especially those using health-related quality-of-life measures. More studies are needed to determine whether the attitudinal differences affect the generalization of results from clinical trials.

Recurrent brain hemorrhage is more frequent than ischemic stroke after intracranial hemorrhage

OBJECTIVE

To characterize the rates of recurrent intracranial hemorrhage (ICH), ischemic stroke, and death in survivors of primary ICH.

METHODS

Systematic review of studies reporting recurrent stroke in survivors of primary ICH, identified at index ICH and followed forward. Studies were identified by computerized search of the literature and review of reference lists.

RESULTS

Ten studies published between 1982 and 2000 reporting 1,880 survivors of ICH, followed for a total of 6,326 patient-years (mean follow-up, 3.4 patient-years), were included. The aggregate rate of all stroke from five studies was 4.3% per patient-year (95% CI, 3.5% to 5.4%). The rate in the three population-based studies was higher than in the two hospital-based studies, 6.2% versus 4.0% per patient-year (p = 0.04). About three fourths of recurrent strokes were ICH. Considering all 10 studies, a total of 147 patients had a recurrent ICH, an aggregate rate of 2.3% per patient-year (95% CI, 1.9% to 2.7%). Based on data from four studies, patients with a primary lobar ICH had a higher rate of recurrent ICH than those with a deep, hemispheric ICH (4.4% versus 2.1% per patient-year; p = 0.002). The aggregate rates of subsequent ischemic stroke and mortality were 1.1% per patient-year (95% CI, 0.8% to 1.7%) and 8.8% per patient-year (95% CI, 5.2% to 11.0%).

CONCLUSIONS

Recurrent stroke among survivors of primary ICH occurs at a rate of about 4% per patient-year, and most are recurrent ICH. Survivors of ICH have a higher risk of recurrent ICH than of ischemic stroke, and this has implications for the use of antithrombotic agents in these 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.

Primary prevention studies and the healthy elderly: evaluating barriers to recruitment

Although primary prevention studies are important tools in helping the healthy elderly stay healthy, recruiting from a community-based cohort of healthy elderly individuals for a primary prevention study involves numerous barriers. To better identify and understand these barriers, we conducted and evaluated a comprehensive recruitment strategy for a primary prevention study testing aspirin in an HMO population. In the recruitment phase, we identified healthy individuals (65 years of age or older) who were members of a large, group-model HMO in Oregon and Washington, and used computerized medical database screening, statistical sampling, health plan mailings, e-mail communication with primary care providers, and the experience of a well-established research clinic in an effort to enroll health elderly in this primary prevention trial. Among a random sample of 47,453 eligible patients over the age of 65, 44% responded to recruitment efforts, but only 3% were enrolled--an overall yield of slightly less than 2%. To evaluate these results, we then conducted focus groups with 225 randomly selected "eligible refusers." We determined that healthy elders were hesitant to give up their choice to use aspirin, unwilling to travel to the research center, and reluctant to risk their tenuous hold on good health to participate in a study of primary prevention. Awareness of these attitudes is an indispensable step toward designing effective recruitment strategies for primary prevention studies involving the healthy elderly.

Assessment of three schemes for stratifying stroke risk in patients with nonvalvular atrial fibrillation

PURPOSE

The risk of ischemic stroke varies widely among patients with nonvalvular atrial fibrillation, influencing the choice of prophylactic antithrombotic therapy. We assessed three schemes for stroke risk stratification in these patients who were treated with aspirin and who did not have prior cerebral ischemia.

SUBJECTS AND METHODS

Criteria from three schemes of risk stratification were applied to a longitudinally observed cohort of patients with atrial fibrillation who did not have prior cerebral ischemia and who were treated with aspirin alone or aspirin combined with low, ineffective doses of warfarin in a multicenter clinical trial. The ability of the schemes to identify patients at high (>/=6%), low (</=2%), and intermediate annual risks of ischemic stroke was assessed.

RESULTS

During a mean follow-up of 1.8 years, 48 ischemic strokes occurred among 1,073 patients with atrial fibrillation who were taking aspirin (rate = 2.5 per 100 person-years). Each of the three schemes predicted stroke and disabling stroke, and successfully identified patients at low risk (observed stroke rates of 0.3 to 1.1 per 100 person-years), although the fractions of the cohort that were categorized as low risk varied from 14% to 45%. The observed rates of ischemic stroke among patients categorized as high risk ranged from 3.5 to 7.2 per 100 person-years among the stratification schemes. Two schemes considered all patients >75 years old as high risk (observed stroke rate 4.2 per 100 person-years), while the remaining scheme classified one third of patients in this age group as low risk (observed stroke rate 0.6 per 100 person-years).

CONCLUSIONS

When tested in a large cohort of patients with atrial fibrillation who were treated with aspirin, available risk-stratification schemes successfully identified patients with low rates of ischemic stroke, but less consistently identified high-risk patients.

Aspirin for the primary prevention of stroke and other major vascular events: meta-analysis and hypotheses

BACKGROUND

Aspirin therapy reduces stroke by about 25% for persons with atherosclerotic vascular disease, but the effect in those without clinically apparent vascular disease is distinctly different.

OBJECTIVE

To define the effect of aspirin use on stroke and other major vascular events when given for primary prevention to persons without clinically recognized vascular disease.

DATA SOURCES AND EXTRACTION

Systematic review of randomized clinical trials and large prospective observational cohort studies examining the relation between aspirin use and stroke in persons at low intrinsic risk. Studies were identified by a computerized search of the English-language literature.

DATA SYNTHESIS

Five randomized trials of primary prevention included 52 251 participants randomized to aspirin doses ranging from 75 to 650 mg/d; the mean overall stroke rate was 0.3% per year during an average follow-up of 4.6 years. Meta-analysis revealed no significant effect on stroke (relative risk = 1.08; 95% confidence interval, 0.95-1.24) contrasting with a decrease in myocardial infarction (relative risk = 0.74; 95% confidence interval, 0.68-0.82). The lack of reduction of stroke by aspirin for primary prevention was incompatible with its protective effect against stroke in patients with manifest vascular disease (P = .001). Intracranial hemorrhage was increased by the regular use of aspirin (relative risk = 1.35; P = .03), similarly for both primary and secondary prevention. In 4 large observational studies, self-selected use of aspirin was consistently associated with higher rates of stroke.

CONCLUSIONS

The effect of aspirin therapy on stroke differs between individuals based on the presence or absence of overt vascular disease, in contrast with the consistent reduction in myocardial infarction by aspirin therapy observed in all populations. We hypothesize that the effect of aspirin therapy on stroke for persons with major risk factors for vascular disease may be intermediate between a substantial decrease for those with manifest vascular disease and a possible small increase for healthy persons due to accentuated intracranial hemorrhage. When aspirin is given for primary prevention of vascular events, available data support using 75 to 81 mg/d.

Stroke prevention in atrial fibrillation

Nonvalvular atrial fibrillation (AF) is an independent risk factor for stroke. The overall risk of ischemic stroke in patients experiencing AF without prior stroke averages about 5% per year, but varies depending on the presence of coexistent thromboembolic risk factors. Patients with AF with low (about 1% per year), moderate (2%-4% per year) and high (> or = 6% per year) stroke risks have been identified, but the generalizability of available risk stratification schemes to clinical practice has not been defined. Adjusted-dose warfarin (target International Normalized Ratio 2-3) is highly efficacious for prevention of stroke in patients with AF (about 60% reduction) and is relatively safe for selected patients, if carefully monitored. Aspirin has a modest effect on reducing stroke (about 20% reduction). The role of transesophageal echocardiography is routine management of AF remains unsettled. Warfarin therapy should be considered for patients with AF predicted to have a high risk of stroke and who can safely receive it. Aspirin may be indicated for patients with AF at low risk for stroke and for those who cannot safely receive adjusted-dose warfarin. For those with moderate stroke risk, individual bleeding risks during anticoagulation and patient preferences should guide antithrombotic therapy.

Stroke with intermittent atrial fibrillation: incidence and predictors during aspirin therapy. Stroke Prevention in Atrial Fibrillation Investigators

OBJECTIVE

This study was performed to characterize the risk of stroke in elderly patients with recurrent intermittent atrial fibrillation (AF).

BACKGROUND

Although intermittent AF is common, relatively little is known about the attendant risk of stroke.

METHODS

A longitudinal cohort study was performed comparing 460 participants with intermittent AF with 1,552 with sustained AF treated with aspirin in the Stroke Prevention in Atrial Fibrillation studies and followed for a mean of two years. Independent risk factors for ischemic stroke were identified by multivariate analysis.

RESULTS

Patients with intermittent AF were, on average, younger (66 vs. 70 years, p < 0.001), were more often women (37% vs. 26% p < 0.001) and less often had heart failure (11% vs. 21%, p < 0.001) than those with sustained AF. The annualized rate of ischemic stroke was similar for those with intermittent (3.2%) and sustained AF (3.3%). In patients with intermittent AF, independent predictors of ischemic stroke were advancing age (relative risk [RR] = 2.1 per decade, p < 0.001), hypertension (RR = 3.4, p = 0.003) and prior stroke (RR = 4.1, p = 0.01). Of those with intermittent AF predicted to be high risk (24%), the observed stroke rate was 7.8% per year (95% confidence interval 4.5 to 14).

CONCLUSIONS

In this large cohort of AF patients given aspirin, those with intermittent AF had stroke rates similar to patients with sustained AF and similar stroke risk factors. Many elderly patients with recurrent intermittent AF have substantial rates of stroke and likely benefit from anticoagulation. High-risk patients with intermittent AF can be identified using the same clinical criteria that apply to patients with sustained AF.

Cardioembolic vs. noncardioembolic strokes in atrial fibrillation: frequency and effect of antithrombotic agents in the stroke prevention in atrial fibrillation studies

BACKGROUND

While atrial fibrillation (AF) increases the risk of cardioembolic stroke, some ischemic strokes in AF patients are noncardioembolic.

OBJECTIVES

To assess ischemic stroke mechanisms in AF and to compare their responses to antithrombotic therapies.

METHODS

On-therapy analyses of ischemic strokes occurring in 3,950 participants in the Stroke Prevention in Atrial Fibrillation I-III clinical trials. Strokes were classified by presumed mechanism according to specified neurologic features by neurologists unaware of antithrombotic therapy.

RESULTS

Of 217 ischemic strokes, 52% were classified as probably cardioembolic, 24% as noncardioembolic, and 24% as of uncertain cause (i.e., 68% of classifiable infarcts were deemed cardioembolic). Compared to those receiving placebo or no antithrombotic therapy, the proportion of cardioembolic stroke was lower in patients taking adjusted-dose warfarin (p = 0.02), while the proportion of noncardioembolic stroke was lower in those taking aspirin (p = 0.06). Most (56%) ischemic strokes occurring in AF patients taking adjusted-dose warfarin were noncardioembolic vs. 16% of strokes in those taking aspirin. Adjusted-dose warfarin reduced cardioembolic strokes by 83% (p < 0.001) relative to aspirin. Cardioembolic strokes were particularly disabling (p = 0.05).

CONCLUSIONS

Most ischemic strokes in AF patients are probably cardioembolic, and these are sharply reduced by adjusted-dose warfarin. Aspirin in AF patients appears to primarily reduce noncardioembolic strokes. AF patients at highest risk for stroke have the highest rates of cardioembolic stroke and have the greatest reduction in stroke by warfarin.

Markers of thrombin and platelet activity in patients with atrial fibrillation: correlation with stroke among 1531 participants in the stroke prevention in atrial fibrillation III study

BACKGROUND AND PURPOSE

Markers of thrombin generation and platelet activation are often elevated in patients with nonvalvular atrial fibrillation, but it is unclear whether such markers usefully predict stroke. Therefore, we undertook the present study to assess the relationship between prothrombin fragment F1.2 (F1.2), beta-thromboglobulin (BTG), fibrinogen, and the factor V Leiden mutation with stroke in atrial fibrillation.

METHODS

Specimens were obtained from 1531 participants in the Stroke Prevention in Atrial Fibrillation III study. The results were correlated with patient features, antithrombotic therapy, and subsequent thromboembolism (ischemic stroke and systemic embolism) by multivariate analysis.

RESULTS

Increased F1.2 levels were associated with age (P<0.001), female sex (P<0.001), systolic blood pressure (P=0.006), and heart failure (P=0.001). F1.2 were not affected by aspirin use and were not associated with thromboembolism after adjustment for age (P=0. 18). BTG levels were higher with advanced age (P=0.006), coronary artery disease (P=0.05), carotid disease (P=0.005), and heart failure (P<0.001), lower in regular alcohol users (P=0.05), and not significantly associated with thromboembolism. Fibrinogen levels were not significantly related to thromboembolism but were associated with elevated BTG levels (P<0.001). The factor V Leiden mutation was not associated with thromboembolism (relative risk 0.5, 95% CI 0.1 to 3.8).

CONCLUSIONS

Elevated F1.2 levels were associated with clinical risk factors for stroke in atrial fibrillation, whereas increased BTG levels were linked to manifestations of atherosclerosis. In this large cohort of patients with atrial fibrillation who were receiving aspirin, F1.2, BTG, fibrinogen, and factor V Leiden were not independent, clinically useful predictors of stroke.

Pathophysiologic correlates of thromboembolism in nonvalvular atrial fibrillation: I. Reduced flow velocity in the left atrial appendage (The Stroke Prevention in Atrial Fibrillation [SPAF-III] study)

Stroke associated with atrial fibrillation (AF) is mainly due to embolism of thrombus formed during stasis of blood in the left atrial appendage (LAA). Pathophysiologic correlates of appendage flow velocity as assessed by transesophageal echocardiography (TEE) in patients with AF have not been defined. To evaluate the hypothesis that reduced velocity is associated with spontaneous echocardiographic contrast and thrombus in the LAA and with clinical embolic events, we measured LAA flow velocity by TEE in 721 patients with nonvalvular AF entering the Stroke Prevention in Atrial Fibrillation (SPAF-III) study. Patient features, TEE findings, and subsequent cardioembolic events were correlated with velocity by multivariate analysis. Patients in AF during TEE displayed lower peak antegrade (emptying) flow velocity (Anu(p)) than those with intermittent AF in sinus rhythm during TEE (33 cm/s vs 61 cm/s, respectively, P <.0001). Anu(p) < 20 cm/s was associated with dense spontaneous echocardiographic contrast (P <.001), appendage thrombus (P <.01), and subsequent cardioembolic events (P <.01). Independent predictors of Anu(p) < 20 cm/s included age (P =.009), systolic blood pressure (P <.001), sustained AF (P =.01), ischemic heart disease (P =.01), and left atrial area (P =.04). Multivariate analysis found both Anu(p) <20 cm/s (relative risk 2.6, P =.02) and clinical risk factors (relative risk 3.3, P =.002) independently associated with LAA thrombus. LAA Anu(p) is reduced in AF and associated with spontaneous echocardiographic contrast, appendage thrombus, and cardioembolic stroke. Systolic hypertension and aortic atherosclerosis, independent clinical predictors of stroke in patients with AF, also correlated with LAA Anu(p). Our results support the role of reduced LAA Anu(p) in the generation of stasis, thrombus formation, and embolism in patients with AF, although other mechanisms also contribute to stroke.

Atrial fibrillation and thromboembolism: a decade of progress in stroke prevention

Atrial fibrillation is associated with a sixfold increased risk for stroke. More than a dozen published randomized trials of anticoagulants or antiplatelet agents for stroke prevention provide solid evidence on which to base antithrombotic prophylaxis. Adjusted-dose warfarin reduces risk for stroke by about 60% compared with placebo, aspirin reduces this risk (primarily for nondisabling stroke) by about 20% compared with placebo, and warfarin reduces it by about 40% compared with aspirin. Warfarin provides maximal protection against stroke at international normalized ratios of 2.0 to 3.0. Risk stratification of patients with atrial fibrillation identifies those who potentially benefit most or least from anticoagulation; this is important because a substantial percentage of patients with atrial fibrillation have relatively low rates of stroke if they are given aspirin. Many elderly patients with recurrent intermittent atrial fibrillation experience high rates of stroke and benefit from anticoagulation. The value of precordial or transesophageal echocardiography in addition to clinical risk stratifiers for stratifying stroke risk is controversial. Altered hemostasis favoring thrombosis may contribute to formation of atrial appendage thrombus, but these conditions remain ill defined. The past decade has brought unprecedented progress toward understanding thromboembolism in patients with atrial fibrillation and has changed the clinical perspective of a prevalent cardiac arrhythmia into an important opportunity for stroke prevention. Making the most of this promise calls for appreciation of the epidemiology of atrial fibrillation and the concept of risk specificity in the face of diverse therapeutic options.

Antithrombotic therapy to prevent stroke in patients with atrial fibrillation: a meta-analysis

PURPOSE

To characterize the efficacy and safety of anticoagulants and antiplatelet agents for prevention of stroke in patients with atrial fibrillation.

DATA SOURCES

Randomized trials identified by using the search strategy developed by the Cochrane Collaboration Stroke Review Group.

STUDY SELECTION

All published randomized trials testing antithrombotic agents to prevent stroke in patients with atrial fibrillation.

DATA EXTRACTION

Data on interventions, number of participants, duration of exposure and occurrence of all stroke (ischemic and hemorrhagic), major extracranial bleeding, and death were extracted independently by two investigators.

DATA SYNTHESIS

Sixteen trials included a total of 9874 participants (mean follow-up, 1.7 years). Adjusted-dose warfarin (six trials, 2900 participants) reduced stroke by 62% (95% CI, 48% to 72%); absolute risk reductions were 2.7% per year for primary prevention and 8.4% per year for secondary prevention. Major extracranial bleeding was increased by warfarin therapy (absolute risk increase, 0.3% per year). Aspirin (six trials, 3119 participants) reduced stroke by 22% (CI, 2% to 38%); absolute risk reductions were 1.5% per year for primary prevention and 2.5% per year for secondary prevention. Adjusted-dose warfarin (five trials, 2837 participants) was more efficacious than aspirin (relative risk reduction, 36% [CI, 14% to 52%]). Other randomized comparisons yielded inconclusive results.

CONCLUSIONS

Adjusted-dose warfarin and aspirin reduce stroke in patients with atrial fibrillation, and warfarin is substantially more efficacious than aspirin. The benefit of antithrombotic therapy was not offset by the occurrence of major hemorrhage among participants in randomized trials. Judicious use of antithrombotic therapy, tailored according to the inherent risk for stroke, importantly reduces stroke in patients with atrial fibrillation.

A patient decision aid regarding antithrombotic therapy for stroke prevention in atrial fibrillation: a randomized controlled trial

CONTEXT

Decision aids are tools designed to help patients participate in the clinical decision-making process.

OBJECTIVE

To determine whether use of an audiobooklet (AB) decision aid explaining the results of a clinical trial affected the decision-making process of study participants.

DESIGN

Randomized controlled trial conducted from May 1997 to April 1998.

SETTING

Fourteen centers that participated in the Stroke Prevention in Atrial Fibrillation (SPAF) III trial.

PARTICIPANTS

A total of 287 patients from the SPAF III aspirin cohort study, in which patients with atrial fibrillation and a relatively low risk of stroke received 325 mg/d of aspirin and were followed up for a mean of 2 years.

INTERVENTION

At the end of SPAF III, participants were randomized to be informed of the study results with usual care plus use of an AB (AB group) vs usual care alone (control group). The AB included pertinent information to help patients decide whether to continue taking aspirin or switch to warfarin.

MAIN OUTCOME MEASURES

Patients' ability to make choices regarding antithrombotic therapy, and 6-month adherence to these decisions. Their knowledge, expectations, decisional conflict (the amount of uncertainty about the course of action to take), and satisfaction with the decision-making process were also measured.

RESULTS

More patients in the AB group made a choice about antithrombotic therapy than in the control group (99% vs 94%; P = .02). Patients in the AB group were more knowledgeable and had more realistic expectations about the risk of stroke and hemorrhage (in the AB group, 53%-80% correctly estimated different risks; in the control group, 16%-28% gave correct estimates). Decisional conflict and satisfaction were similar for the 2 groups. After 6 months, a similar percentage of patients were still taking their initial choice of antithrombotic therapy (95% vs 93%; P = .44).

CONCLUSIONS

For patients with atrial fibrillation who had participated in a major clinical trial, the use of an AB decision aid improved their understanding of the benefits and risks associated with different treatment options and helped them make definitive choices about which therapy to take. Further studies are necessary to evaluate the acceptability and impact of decision aids in other clinical settings.

Increased risk of intracranial hemorrhage when aspirin is combined with warfarin: A meta-analysis and hypothesis

BACKGROUND

Oral anticoagulation with vitamin K antagonists increases the risk of intracranial hemorrhage; whether addition of aspirin to oral anticoagulation augments this risk is unclear.

METHODS

Meta-analysis of randomized clinical trials in which aspirin was added to oral anticoagulants.

RESULTS

Six randomized clinical trials were identified, including a total of 3,874 participants. Use of aspirin with oral anticoagulants was associated with more than double the frequency of intracranial hemorrhage (relative risk = 2.4, 95% CI = 1.2-4.8, p = 0.02).

CONCLUSION

We hypothesize that aspirin when added to oral vitamin K antagonists may increase the risk of intracranial hemorrhage, but this observation requires confirmation. The magnitude of this effect is uncertain, and the clinical importance is likely different for different patient populations.

Factors associated with ischemic stroke during aspirin therapy in atrial fibrillation: analysis of 2012 participants in the SPAF I-III clinical trials. The Stroke Prevention in Atrial Fibrillation (SPAF) Investigators

BACKGROUND AND PURPOSE

Nonvalvular atrial fibrillation (AF) is a strong, independent risk factor for stroke, but the absolute rate of stroke varies widely among AF patients, importantly influencing the potential benefit of antithrombotic prophylaxis. We explore factors associated with ischemic stroke in AF patients taking aspirin.

METHODS

We performed multivariate logistic regression analysis of 2012 participants given aspirin alone or in combination with low, inefficacious doses of warfarin in the Stroke Prevention in Atrial Fibrillation I-III trials followed for a mean of 2.0 years, during which 130 ischemic strokes were observed.

RESULTS

Age (relative risk [RR]=1.8 per decade, P<0.001), female sex (RR=1.6, P=0.01), history of hypertension (RR=2.0, P<0.001), systolic blood pressure >160 mm Hg (RR=2.3, P<0.001), and prior stroke or transient ischemic attack (RR=2.9, P<0.001) were independently associated with increased stroke risk. Regular consumption of >/=14 alcohol-containing drinks per week was associated with reduced stroke risk (adjusted RR=0.4, P=0.04). Among SPAF III participants, estrogen hormone replacement therapy was associated with a higher risk of ischemic stroke (adjusted RR=3.2, P=0.007). With the use of these variables, a risk stratification scheme for primary prevention separated participants into those with high (7.1%/y, 22% of the cohort), moderate (2.6%/y, 37% of the cohort), and low (0.9%/y, 41% of the cohort) rates of stroke. Ischemic strokes in low-risk participants were less often disabling (P<0.001).

CONCLUSIONS

Patients with AF who have high and low rates of stroke during treatment with aspirin can be identified. However, validation of our risk stratification scheme is necessary before it can be applied with confidence to clinical management. Postmenopausal estrogen replacement therapy and moderate alcohol consumption may additionally modify the risk of stroke in AF, but these findings require confirmation.

Stroke: part II. Management of acute ischemic stroke

Optimal treatment of the patient who has sustained an acute ischemic stroke requires rapid assessment and early intervention. The leisurely approach to acute stroke management sometimes taken in the past should be replaced by an approach that treats stroke as a true medical emergency. Thrombolysis with tissue plasminogen activator has been labeled for the treatment of acute ischemic stroke, but it must be given within three hours of stroke onset. However, fibrinolytic therapy can be given safely to only a fraction of patients with acute stroke, and more broadly applicable therapies are needed. Recent evidence does not support the routine use of heparin in patients with acute stroke, and early use of aspirin offers only modest benefit. Neuroprotective therapies designed to interfere with cytotoxic events initiated by ischemia are undergoing clinical trials that should be completed within the next year. At present, only tissue plasminogen activator has been labeled for acute stroke treatment; however, other agents are on the horizon, and much can be done supportively to improve neurologic outcome. Because of the unique susceptibility of neurons to ischemia, minutes count. Thus, hospitals providing care for patients with acute stroke should organize clinical protocols and pathways for effective implementation of therapies.

Stroke: part I. A clinical update on prevention

Clinical trials conducted during the past five years have yielded important results that have allowed us to refine our approach to stroke prevention. Treatment of isolated systolic hypertension prevents stroke and is generally well tolerated. New antiplatelet agents (clopidogrel and the combination of aspirin plus high-dose dipyridamole) have been shown to be effective in reducing vascular events in survivors of ischemic stroke, although aspirin remains the mainstay of antiplatelet therapy for stroke prevention. Several clinical trials support the benefit of lipid-lowering agents ("statins") in reducing stroke. Warfarin reduces stroke for high-risk patients with atrial fibrillation. Carotid endarterectomy is highly beneficial in reducing stroke for symptomatic patients with severe carotid stenosis (greater than 70 percent), but the benefit is less for symptomatic patients with a moderate degree of stenosis (50 to 69 percent) and for patients with asymptomatic carotid disease of any severity.

Aortic plaque in atrial fibrillation: prevalence, predictors, and thromboembolic implications

BACKGROUND AND PURPOSE

Thoracic aortic plaque identified by transesophageal echocardiography heightens the risk of stroke associated with atrial fibrillation (AF). We sought to identify the prevalence, predictors, and implications of aortic plaque in patients with nonvalvular AF.

METHODS

Thoracic aortic plaque was prospectively sought in 770 persons with AF with the use of transesophageal echocardiography and classified as simple or complex on the basis of thickness >/=4 mm, ulceration, or mobility. Clinical and echocardiographic features of thromboembolism were correlated by multivariate analysis.

RESULTS

Aortic plaque was detected in 57% of the cohort, and complex plaque was detected in 25%. Both were found more frequently in the descending than in the proximal aorta. Potentially etiologic patient characteristics independently associated with complex plaque included advanced age, history of hypertension, diabetes, and past or present tobacco use. Comorbidities associated with aortic plaque were prior thromboembolism, increased pulse pressure, ischemic heart disease, stenosis or sclerosis of the aortic valve, mitral annular calcification (>10%), elevated serum creatinine concentration, spontaneous echo contrast in the left atrium or appendage, and left atrial appendage thrombus. The prevalence of complex plaque in patients aged <70 years with <10% mitral annular calcification, without ischemic heart disease, or without pulse pressure >/=65 mm Hg was 4% (95% CI, 1% to 6%).

CONCLUSIONS

Aortic plaque is prevalent in patients with AF and is associated with atherosclerosis risk factors and with left atrial stasis or thrombosis, which are themselves independent stroke risk factors. Since the predominant location of complex plaque was in the descending aorta, the role of aortic plaque as a source of embolism in AF is uncertain.

Left atrial diameter in nonvalvular atrial fibrillation: An echocardiographic study. Stroke Prevention in Atrial Fibrillation Investigators

BACKGROUND

The left atrium (LA) is usually enlarged in patients with nonvalvular atrial fibrillation (AF), but factors associated with LA diameter are incompletely defined.

METHODS AND RESULTS

This transthoracic echocardiographic cohort study includes 3465 participants with nonvalvular AF in 3 multicenter clinical trials. LA diameter determined by M-mode echocardiography was correlated with clinical and echocardiographic features by cross-sectional multivariate regression analyses. The mean LA diameter was 47 +/- 8 mm, on average 6 mm larger in those with AF at the time of echocardiography than in those with sinus rhythm (48 vs 42 mm, P <. 001). Patient age and body weight were independently predictive of LA diameter (P <.0001), but sex, body surface area, and body mass index were not. The estimated independent contribution of atrial rhythm to LA diameter was approximately 2.5 mm. Prolonged duration of AF, left ventricular dilatation and increased muscle mass, mitral regurgitation, annular calcification, and hypertension were additional independent predictors of LA diameter.

CONCLUSIONS

Multiple factors appear to contribute to LA enlargement in patients with nonvalvular AF, including the presence and persistence of the dysrhythmia.

Stroke risk in an elderly population with atrial fibrillation

Patients with nonvalvular atrial fibrillation (AF) have an increased risk of stroke, but the absolute rate of stroke varies widely depending on coexistent vascular disease. We assessed the stroke rate and predictive value of two published schemes for stroke risk stratification in a population-derived cohort of 259 elderly people with nonvalvular AF followed for a median of 5.3 years. The rate of ischemic stroke was 2.8% per year (95% confidence interval [CI] 1.9, 3.9). Thirty-one percent were predicted to be at low risk, and their stroke rate was 1.7% per year (95% CI 0.6, 3.8). Many people with AF in this population-derived cohort had relatively low rates of stroke. Further studies to reliably stratify stroke risk in patients with AF are needed.

Prevention of stroke in patients with nonvalvular atrial fibrillation

OBJECTIVE

To review the risk and pathogenesis of stroke associated with nonvalvular atrial fibrillation (AF) and the efficacies and risks of stroke prevention strategies.

BACKGROUND

About 16% of ischemic strokes are associated with AF; AF is an independent risk factor for stroke.

METHODS

Review of the literature, focusing on 13 randomized trials of antithrombotic therapy.

RESULTS

The overall risk of stroke in AF patients averages about 5%/y, but with wide variation depending on the presence of coexistent thromboembolic risk factors. AF patients with low (about 1% per year), moderate (about 3% per year), and high (about 6% per year) stroke risks have been identified, but the generalizability of risk stratification schemes to clinical practice has not been fully assessed. AF patients with prior stroke or transient ischemic attack, even if remote, are at highest risk (about 12% per year). Adjusted-dose warfarin (target International Normalized Ratio [INR] 2-3) is highly efficacious for preventing stroke in AF patients (about 70% risk reduction) and is safe for selected patients, if carefully monitored. Aspirin has a modest effect on reducing stroke (about 20% risk reduction). The numbers of AF patients that would need to be treated with warfarin instead of aspirin for 1 year to prevent one ischemic stroke are about 200, 70, and 20 for those with low, moderate and high risk, respectively.

CONCLUSIONS

Many patients with nonvalvular AF have substantial rates of ischemic stroke. Stratification of stroke risk identifies AF patients who benefit most and least from lifelong anticoagulation. Warfarin is recommended for high-risk AF patients who can safely receive it. Aspirin may be indicated for those with a low stroke risk and for those who cannot receive warfarin. For AF patients considered to have a moderate risk of stroke, individual bleeding risk during anticoagulation and patient preference should particularly influence the choice of antithrombotic prophylaxis.

Transesophageal echocardiographic correlates of clinical risk of thromboembolism in nonvalvular atrial fibrillation. Stroke Prevention in Atrial Fibrillation III Investigators

OBJECTIVES

This study explored the mechanisms linking clinical and precordial echocardiographic predictors to thromboembolism in atrial fibrillation (AF) by assessing transesophageal echocardiographic (TEE) correlations.

BACKGROUND

Clinical predictors of thromboembolism in patients with nonvalvular AF have been identified, but their mechanistic links remain unclear. TEE provides imaging of the left atrium, its appendage and the proximal thoracic aorta, potentially clarifying stroke mechanisms in patients with AF.

METHODS

Cross-sectional analysis of TEE features correlated with low, moderate and high thromboembolic risk during aspirin therapy among 786 participants undergoing TEE on entry into the Stroke Prevention in Atrial Fibrillation III trial.

RESULTS

TEE features independently associated with increased thromboembolic risk were appendage thrombi (relative risk [RR] 2.5, p = 0.04), dense spontaneous echo contrast (RR 3.7, p < 0.001), left atrial appendage peak flow velocities < or = 20 cm/s (RR 1.7, p = 0.008) and complex aortic plaque (RR 2.1, p < 0.001). Patients with AF with a history of hypertension (conferring moderate risk) more frequently had atrial appendage thrombi (RR 2.6, p < 0.001) and reduced flow velocity (RR 1.8, p = 0.003) than low risk patients. Among low risk patients, those with intermittent AF had similar TEE features to those with constant AF.

CONCLUSIONS

TEE findings indicative of atrial stasis or thrombosis and of aortic atheroma were independently associated with high thromboembolic risk in patients with AF. The increased stroke risk associated with a history of hypertension in AF appears to be mediated primarily through left atrial stasis and thrombi. The presence of complex aortic plaque distinguished patients with AF at high risk from those at moderate risk of thromboembolism.

Aspirin use and incident stroke in the cardiovascular health study. CHS Collaborative Research Group

BACKGROUND AND PURPOSE

Randomized clinical trials testing aspirin in relatively low-risk, middle-aged people have consistently shown small increases in stroke associated with aspirin use. We analyzed the relationship between the regular use of aspirin and incident ischemic and hemorrhagic stroke among people aged 65 years or older participating in the Cardiovascular Health Study.

METHODS

We conducted a multivariate analysis of incident stroke rates in a prospectively assessed, observational cohort of 5011 elderly people followed for a mean of 4.2 years.

RESULTS

Participants had a mean age of 72 years, and 58% were women. Twenty-three percent used aspirin frequently, and 17% used aspirin infrequently at study entry. Frequent aspirin use was associated with an increased rate of ischemic stroke compared with nonusers (relative risk= 1.6; 95% confidence interval [CI], 1.2 to 2.2; P=0.001). After adjustment for other stroke risk factors, women who used aspirin frequently or infrequently at study entry had a 1.8-fold (95% CI, 1.2 to 2.8) and 1.6-fold (95% CI, 0.9 to 3.0) increased risk of ischemic stroke, respectively (P<0.01, test for trend), compared with nonusers. In men, aspirin use was not statistically significantly associated with stroke risk. Findings were similar when aspirin use in the years before the incident stroke was used in the modeling. Aspirin use at entry was also associated with a 4-fold (95% CI, 1.6 to 10.0) increase in risk of hemorrhagic stroke for both infrequent and frequent users of aspirin (P=0.003).

CONCLUSIONS

Aspirin use was associated with increased risks of ischemic stroke in women and hemorrhagic stroke overall in this elderly cohort, after adjustment for other stroke predictors. The possibility exists of confounding by reasons for aspirin use rather than cause and effect. Whether regular aspirin use increases stroke risk for elderly people without cardiovascular disease can only be determined by randomized clinical trials.

Survey of the causes of stroke among Mexican Americans in South Texas

Management strategies for optimal stroke prevention depend on the cause of threatened stroke. We know relatively little about the etiology of stroke in Mexican Americans, who make up one quarter of the population in Texas. A retrospective case series of 159 consecutive patients hospitalized in San Antonio, Tex, for acute, first-ever stroke compared risk factors, features, and causes of stroke between Mexican Americans and whites. Mexican Americans who had strokes were significantly younger than whites and had diabetes mellitus more often. Intracerebral hemorrhage and lacunar infarcts occurred often in Mexican Americans. Ethnicity appeared to be an independent risk factor for lacunar infarction. Mortality and functional outcome at the time of hospital discharge were similar in Mexican Americans and whites. Intrinsic small-vessel disease causing lacunar infarcts and intracerebral hemorrhage accounts for about one half of strokes in Mexican Americans. Stroke among Mexican Americans in South Texas has a distinctive profile with implications for its prevention.

Coping with pediatric death in the ED by learning from parental experience

The death of a pediatric patient in the emergency department generates an intense emotional response in the physician and staff. A majority of emergency physicians describe this as the most stressful event in emergency medicine. Few emergency physicians are instructed in the complexities of dealing with the death of a child. The authors have developed a teaching module that introduces aspects of pediatric death-telling through the eyes of parents who have personally experienced the death of a child.