Cognitive Decline Over Time in Patients With Systolic Heart Failure: Insights From WARCEF.

OBJECTIVES: This study sought to characterize cognitive decline (CD) over time and its predictors in patients with systolic heart failure (HF). BACKGROUND: Despite the high prevalence of CD and its impact on mortality, predictors of CD in HF have not been established. METHODS: This study investigated CD in the WARCEF (Warfarin versus Aspirin in Reduced Ejection Fraction) trial, which performed yearly Mini-Mental State Examinations (MMSE) (higher scores indicate better cognitive function; e.g., normal score: 24 or higher). A longitudinal time-varying analysis was performed among pertinent covariates, including baseline MMSE and MMSE scores during follow-up, analyzed both as a continuous variable and a 2-point decrease. To account for a loss to follow-up, data at the baseline and at the 12-month visit were analyzed separately (sensitivity analysis). RESULTS: A total of 1,846 patients were included. In linear regression, MMSE decrease was independently associated with higher baseline MMSE score (p < 0.0001), older age (p < 0.0001), nonwhite race/ethnicity (p < 0.0001), and lower education (p < 0.0001). In logistic regression, CD was independently associated with higher baseline MMSE scores (odds ratio [OR]: 1.13; 95% confidence interval [CI]: 1.07 to 1.20]; p < 0.001), older age (OR: 1.37; 95% CI: 1.24 to 1.50; p < 0.001), nonwhite race/ethnicity (OR: 2.32; 95% CI: 1.72 to 3.13 for black; OR: 1.94; 95% CI: 1.40 to 2.69 for Hispanic vs. white; p < 0.001), lower education (p < 0.001), and New York Heart Association functional class II or higher (p = 0.03). Warfarin and other medications were not associated with CD. Similar trends were seen in the sensitivity analysis (n = 1,439). CONCLUSIONS: CD in HF is predicted by baseline cognitive status, demographic variables, and NYHA functional class. The possibility of intervening on some of its predictors suggests the need for the frequent assessment of cognitive function in patients with HF. (Warfarin versus Aspirin in Reduced Cardiac Ejection Fraction [WARCEF]; NCT00041938).

Association between mortality and implantable cardioverter-defibrillators by aetiology of heart failure: a propensity-matched analysis of the WARCEF trial.

AIMS: There is debate on whether the beneficial effect of implantable cardioverter-defibrillators (ICDs) is attenuated in patients with non-ischaemic cardiomyopathy (NICM). We assess whether any ICD benefit differs between patients with NICM and those with ischaemic cardiomyopathy (ICM), using data from the Warfarin versus Aspirin in Reduced Cardiac Ejection Fraction (WARCEF) trial. METHODS AND RESULTS: We performed a post hoc analysis using WARCEF (N = 2293; ICM, n = 991 vs. NICM, n = 1302), where participants received optimal medical treatment. We developed stratified propensity scores for having an ICD at baseline using 41 demographic and clinical variables and created 1:2 propensity-matched cohorts separately for ICM patients with ICD (N = 223 with ICD; N = 446 matched) and NICM patients (N = 195 with ICD; N = 390 matched). We constructed a Cox proportional hazards model to assess the effect of ICD status on mortality for patients with ICM and those with NICM and tested the interaction between ICD status and aetiology of heart failure. During mean follow-up of 3.5 ± 1.8 years, 527 patients died. The presence of ICD was associated with a lower risk of all-cause death among those with ICM (hazard ratio: 0.640; 95% confidence interval: 0.448 to 0.915; P = 0.015) but not among those with NICM (hazard ratio: 0.984; 95% confidence interval: 0.641 to 1.509; P = 0.941). There was weak evidence of interaction between ICD status and the aetiology of heart failure (P = 0.131). CONCLUSIONS: The presence of ICD is associated with a survival benefit in patients with ICM but not in those with NICM.

Left atrial volume and cardiovascular outcomes in systolic heart failure: effect of antithrombotic treatment.

AIMS: Left atrium (LA) dilation is associated with adverse cardiovascular (CV) outcomes. Blood stasis, thrombus formation and atrial fibrillation may occur, especially in heart failure (HF) patients. It is not known whether preventive antithrombotic treatment may decrease the incidence of CV events in HF patients with LA enlargement. We investigated the relationship between LA enlargement and CV outcomes in HF patients and the effect of different antithrombotic treatments. METHODS AND RESULTS: Two-dimensional echocardiography with LA volume index (LAVi) measurement was performed in 1148 patients with systolic HF from the Warfarin versus Aspirin in Reduced Ejection Fraction (WARCEF) trial. Patients were randomized to warfarin or aspirin and followed for 3.4 ± 1.7 years. While the primary aim of the trial was a composite of ischaemic stroke, death, and intracerebral haemorrhage, the present report focuses on the individual CV events, whose incidence was compared across different LAVi and treatment subgroups. After adjustment for demographics and clinical covariates, moderate or severe LA enlargement was significantly associated with total death (hazard ratio 1.6 and 2.7, respectively), CV death (HR 1.7 and 3.3), and HF hospitalization (HR 2.3 and 2.6) but not myocardial infarction (HR 1.0 and 1.4) or ischaemic stroke (1.1 and 1.5). The increased risk was observed in both patients treated with warfarin or aspirin. In warfarin-treated patients, a time in therapeutic range >60% was associated with lower event rates, and an interaction between LAVi and time in therapeutic range was observed for death (P = 0.034). CONCLUSIONS: In patients with systolic HF, moderate or severe LA enlargement is associated with death and HF hospitalization despite treatment with antithrombotic medications. The possibility that achieving a more consistent therapeutic level of anticoagulation may decrease the risk of death requires further investigation.

Heart Failure Severity and Quality of Warfarin Anticoagulation Control (From the WARCEF Trial).

Previous studies in patients with atrial fibrillation showed that a history of heart failure (HF) could negatively impact anticoagulation quality, as measured by the average time in therapeutic range (TTR). Whether additional markers of HF severity are associated with TTR has not been investigated thoroughly. We aimed to examine the potential role of HF severity in the quality of warfarin control in patients with HF with reduced ejection fraction. Data from the Warfarin versus Aspirin in Reduced Cardiac Ejection Fraction Trial were used to investigate the association between TTR and HF severity. Multivariable logistic regression models were used to examine the association of markers of HF severity, including New York Heart Association (NYHA) class, Minnesota Living with HF (MLWHF) score, and frequency of HF hospitalization, with TTR ≥70% (high TTR). We included 1,067 participants (high TTR, N = 413; low TTR, N = 654) in the analysis. In unadjusted analysis, patients with a high TTR were older and less likely to have had strokes or receive other antiplatelet agents. Those patients also had lower NYHA class, better MLWHF scores, greater 6-minute walk distance, and lower frequency of HF hospitalizations. Multivariable analysis showed that NYHA class III and/or IV (Odds ratio [OR] 0.68 [95% confidence intervals [CIs] 0.49 to 0.94]), each 10-point increase in MLWHF score (i.e., worse health-related quality of life) (OR 0.92 [0.86 to 0.99]), and higher number of HF hospitalization per year (OR0.45 [0.30 to 0.67]) were associated with decreased likelihood of having high TTR. In HF patients with systolic dysfunction, NYHA class III and/or IV, poor health-related quality of life, and a higher rate of HF hospitalization were independently associated with suboptimal quality of warfarin anticoagulation control. These results affirm the need to assess the new approaches, such as direct oral anticoagulants, to prevent thromboembolism in this patient population.

Resting Heart Rate and Ischemic Stroke in Patients with Heart Failure.

BACKGROUND: Although high resting heart rate (RHR) is known to be associated with an increased risk of mortality and hospital admission in patients with heart failure, the relationship between RHR and ischemic stroke remains unclear. This study is aimed at investigating the relationship between RHR and ischemic stroke in patients with heart failure in sinus rhythm. METHODS: We examined 2,060 patients with systolic heart failure in sinus rhythm from the Warfarin versus Aspirin in Reduced Cardiac Ejection Fraction trial. RHR was determined from baseline electrocardiogram, and was examined as both a continuous variable and a categorical variable using quartiles. Ischemic strokes were identified during follow-up and adjudicated by physician review. RESULTS: During 3.5 ± 1.8 years of follow-up, 77 patients (5.3% from Kaplan-Meier [KM] curve) experienced an ischemic stroke. The highest incidence of ischemic stroke (21/503 [KM 6.9%]) was observed in the lowest RHR quartile (RHR <64 beats/min) compared to other groups; 22/573 (KM 5.3%) in 64-70 beats/min, 13/465 (KM 3.5%) in 71-79 beats/min, and 21/519 (KM 5.4%) in RHR >79 beats/min (p = 0.693). Multivariable Cox proportional hazards analysis revealed that RHR was significantly associated with ischemic stroke (hazard ratio per unit decrease: 1.07, 95% CI 1.02-1.13, when RHR <64/beats/min; p = 0.038), along with a history of stroke or transient ischemic attack and left ventricular ejection fraction. CONCLUSIONS: In contrast to its beneficial effect on mortality and hospital re-admissions, lower RHR may increase the risk of ischemic stroke in patients with systolic heart failure in sinus rhythm.

Behavioural improvement in a minimally conscious state after caloric vestibular stimulation: evidence from two single case studies.

OBJECTIVE: To investigate whether caloric vestibular stimulation, a non-invasive form of neuro-modulation, alters the level of awareness in people residing in a minimally conscious state. DESIGN: Single-case ( n = 2), prospective, controlled (ABAB) efficacy study. SETTING: Tertiary, neuro-rehabilitation inpatient ward within a university hospital. PARTICIPANTS: Two individuals in a minimally conscious state. INTERVENTION: Left ear caloric vestibular stimulation was performed in two four/five-week blocks interleaved with two four/five-week blocks of sham stimulation. Session duration and frequency gradually increased within each block from once per day for 10 minutes (Week 1) to once per day for 20 minutes (Week 2) to 20 minutes twice per day in the remaining weeks. MEASURES: Wessex Head Injury Matrix, JFK Coma Recovery Scale - Revised. RESULTS: Both participants' Wessex Head Injury Matrix scores indicated a transition from involuntary (i.e. mechanical vocalization) to voluntary (i.e. gesture making, selective responses to family members) behaviour that was time-locked to the onset of active stimulation. In one participant, this improvement persisted for at least four weeks after active stimulation, while in the other it diminished two weeks after stimulation. Allied, although less dramatic, changes were seen on the arousal and auditory subscales of the JFK Coma Recovery Scale - Revised. CONCLUSION: The data provide the first evidence that vestibular stimulation may help improve outcome in a low awareness state, although further studies are needed to replicate effect and determine longer-term benefit.

CHA2 DS2 -VASc score and adverse outcomes in patients with heart failure with reduced ejection fraction and sinus rhythm.

AIMS: The aim of this study was to determine whether the CHA2 DS2 -VASc score can predict adverse outcomes such as death, ischaemic stroke, and major haemorrhage, in patients with systolic heart failure in sinus rhythm. METHODS AND RESULTS: CHA2 DS2 -VASc scores were calculated for 1101 patients randomized to warfarin and 1123 patients randomized to aspirin. Adverse outcomes were defined as death or ischaemic stroke, death alone, ischaemic stroke alone, and major haemorrhage. Using proportional hazards models, we found that each 1-point increase in the CHA2 DS2 -VASc score was associated with increased hazard of death or ischaemic stroke events [hazard ratio (HR) for the warfarin arm = 1.21, 95% confidence interval (CI) 1.13-1.30, P < 0.001; for aspirin, HR = 1.20, 95% CI 1.11-1.29, P < 0.001]. Similar increased hazards for higher CHA2 DS2 -VASc scores were observed for death alone, ischaemic stroke alone, and major haemorrhage. Overall performance of the CHA2 DS2 -VASc score was assessed using c-statistics for full models containing the risk score, treatment assignment, and score-treatment interaction, with the c-statistics for the full models ranging from 0.57 for death to 0.68 for major haemorrhage. CONCLUSIONS: The CHA2 DS2 -VASc score predicted adverse outcomes in patients with systolic heart failure in sinus rhythm, with modest prediction accuracy.

Left Ventricular Ejection Fraction and Risk of Stroke and Cardiac Events in Heart Failure: Data From the Warfarin Versus Aspirin in Reduced Ejection Fraction Trial.

BACKGROUND AND PURPOSE: In heart failure (HF), left ventricular ejection fraction (LVEF) is inversely associated with mortality and cardiovascular outcomes. Its relationship with stroke is controversial, as is the effect of antithrombotic treatment. We studied the relationship of LVEF with stroke and cardiovascular events in patients with HF and the effect of different antithrombotic treatments. METHODS: In the Warfarin Versus Aspirin in Reduced Ejection Fraction (WARCEF) trial, 2305 patients with systolic HF (LVEF≤35%) and sinus rhythm were randomized to warfarin or aspirin and followed for 3.5±1.8 years. Although no differences between treatments were observed on primary outcome (death, stroke, or intracerebral hemorrhage), warfarin decreased the stroke risk. The present report compares the incidence of stroke and cardiovascular events across different LVEF and treatment subgroups. RESULTS: Baseline LVEF was inversely and linearly associated with primary outcome, mortality and its components (sudden and cardiovascular death), and HF hospitalization, but not myocardial infarction. A relationship with stroke was only observed for LVEF of <15% (incidence rates: 2.04 versus 0.95/100 patient-years; P=0.009), which more than doubled the adjusted stroke risk (adjusted hazard ratio, 2.125; 95% CI, 1.182-3.818; P=0.012). In warfarin-treated patients, each 5% LVEF decrement significantly increased the stroke risk (adjusted hazard ratio, 1.346; 95% CI, 1.044-1.737; P=0.022; P value for interaction=0.04). CONCLUSIONS: In patients with systolic HF and sinus rhythm, LVEF is inversely associated with death and its components, whereas an association with stroke exists for very low LVEF values. An interaction with warfarin treatment on stroke risk may exist. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT00041938.

A Stroke Registry Data on the Use of Intravenous Recombinant Tissue Plasminogen Activator in Stroke of Unknown Time of Onset.

BACKGROUND: Stroke of unknown time of onset (SUTO) constitutes one fifth of all ischemic stroke admissions, and routine use of intravenous recombinant tissue plasminogen activator (IV rtPA) is recommended only in patients with a symptom onset time of less than 4.5 hours. There are limited data on clinical outcome in patients with SUTO versus patients with symptoms onset less than 4.5 hours from onset time. We hypothesized that efficacy and safety outcomes of IV rtPA therapy in selected SUTO patients are comparable to those with known onset time. METHODS: We compared 90 days' modified Rankin Scale (mRS), rates of symptomatic intracerebral hemorrhage (sICH), in-hospital mortality, and death due to sICH between 3 groups treated with IV rtPA: SUTO, 3 hours or less, and 3.0-4.5 hours from prospective patient admissions between April 1, 2012, and July 31, 2013. RESULTS: There were 65 participants in the SUTO group, 186 in the 3 hours or less group, and 51 in the 3.0-4.5 hours group. In-hospital mortality rates were 14.5%, 13.5%, and 11.8%, respectively. sICH risks were 1.5%, 1.6%, and 5.8%, and death rates due to sICH were 0%, 1.1%, and 1.9%, respectively. Ninety days' odds of excellent clinical outcome (mRS score 0-1) were not different between the SUTO group (odds ratio [OR] 1.14, 95% confidence interval [CI]: .63-2.10), the 3 hours or less group (OR .87, 95% CI: .48-1.60), and the 3.0-4.5 hours group (OR .79, 95% CI: .48-1.60) (P = .82). CONCLUSION: Thrombolytic therapy outcome in SUTO is not different from in-license use in our patient population. There is an urgent need to include this patient group in ongoing randomized multicenter trials.

Clinical and Echocardiographic Factors Associated With New-Onset Atrial Fibrillation in Heart Failure　- Subanalysis of the WARCEF Trial.

BACKGROUND: Heart failure (HF) patients have a high incidence of new-onset AF. Given the adverse prognostic influence of AF in HF, identifying patients at high risk of developing AF is important. METHODS AND RESULTS: The incidence and factors associated with new-onset AF were investigated in patients in sinus rhythm with reduced LVEF enrolled in the Warfarin versus Aspirin in Reduced Cardiac Ejection Fraction (WARCEF) trial. Analyses involved clinical factors alone (n=2,219), and clinical plus echocardiographic findings (n=1,125). During 3.5±1.8 years of follow-up, 212 patients (9.6% of total cohort) developed AF. In both samples, new-onset AF was associated with age, male sex, White race, and IHD. Among echocardiographic variables, only LAD predicted AF. On multivariate Cox modeling, age (HR, 1.02; 95% CI: 1.00-1.03, P=0.008), IHD (HR, 1.37; 95% CI: 1.02-1.84, P=0.036) and LAD (HR, 1.48; 95% CI: 1.15-1.91, P=0.003) remained associated with AF onset. Patients with IHD, LAD>4.5 cm and age>50 years had a 2.5-fold higher risk of AF than patients without any of these characteristics (HR, 2.52; 95% CI: 1.72-3.69, P<0.0001). CONCLUSIONS: Age, IHD and LAD independently predict new-onset AF in HF patients in sinus rhythm, at younger age and smaller LAD than generally believed. This information may be useful to risk-stratify HF patients for AF development, allowing close monitoring and possibly early detection. (Circ J 2016; 80: 619-626).

The first prognostic model for stroke and death in patients with systolic heart failure.

BACKGROUND: Patients with systolic heart failure (HF) are at increased risk of both ischemic stroke and death. Currently, no risk scores are available to identify HF patients at high risk of stroke or death. The Warfarin vs. Aspirin in Reduced Cardiac Ejection Fraction (WARCEF) trial studied 2305 HF patients, in sinus rhythm, followed for up to 6 years (3.5±1.5 years). This trial showed no overall difference in those treated with warfarin vs aspirin with regard to death or stroke. The present study develops the first prognostic model to identify patients at higher risk of stroke or death based on their overall risk profile. METHODS AND RESULTS: A scoring algorithm using 8 readily obtainable clinical characteristics as predictors, age, gender, hemoglobin, blood urea nitrogen, ejection fraction, diastolic blood pressure, diabetes status, and prior stroke or transient ischemic attack (C-index=0.65, 95% CI: 0.613-0.681), was developed. It was validated internally using a bootstrap method. In predicting 1-year survival for death alone, our 8-predictor model had an AUC of 0.63 (95% CI: 0.579-0.678) while the 14-predictor Seattle model had an AUC of 0.72. The Seattle model did not report stroke. CONCLUSIONS: This novel prognostic model predicts the overall risk of ischemic stroke or death for HF patients. This model compares favorably for death with the Seattle model and has the added utility of including stroke as an endpoint. Use of this model will help identify those patients in need of more intensive monitoring and therapy and may help identify appropriate populations for trials of new therapies. CLINICAL TRIAL REGISTRATION: http://www.Clinicatrials.govNCT00041938.

Bleeding Risk and Antithrombotic Strategy in Patients With Sinus Rhythm and Heart Failure With Reduced Ejection Fraction Treated With Warfarin or Aspirin.

We sought to assess the performance of existing bleeding risk scores, such as the Hypertension, Abnormal Renal/Liver Function, Stroke, Bleeding History or Predisposition, Labile INR, Elderly, Drugs/Alcohol Concomitantly (HAS-BLED) score or the Outpatient Bleeding Risk Index (OBRI), in patients with heart failure with reduced ejection fraction (HFrEF) in sinus rhythm (SR) treated with warfarin or aspirin. We calculated HAS-BLED and OBRI risk scores for 2,305 patients with HFrEF in SR enrolled in the Warfarin versus Aspirin in Reduced Cardiac Ejection Fraction trial. Proportional hazards models were used to test whether each score predicted major bleeding, and comparison of different risk scores was performed using Harell C-statistic and net reclassification improvement index. For the warfarin arm, both scores predicted bleeding risk, with OBRI having significantly greater C-statistic (0.72 vs 0.61; p = 0.03) compared to HAS-BLED, although the net reclassification improvement for comparing OBRI to HAS-BLED was not significant (0.32, 95% confidence interval [CI] -0.18 to 0.37). Performance of the OBRI and HAS-BLED risk scores was similar for the aspirin arm. For participants with OBRI scores of 0 to 1, warfarin compared with aspirin reduced ischemic stroke (hazard ratio [HR] 0.51, 95% CI 0.26 to 0.98, p = 0.042) without significantly increasing major bleeding (HR 1.24, 95% CI 0.66 to 2.30, p = 0.51). For those with OBRI score of ≥2, there was a trend for reduced ischemic stroke with warfarin compared to aspirin (HR 0.56, 95% CI 0.27 to 1.15, p = 0.12), but major bleeding was increased (HR 4.04, 95% CI 1.99 to 8.22, p <0.001). In conclusion, existing bleeding risk scores can identify bleeding risk in patients with HFrEF in SR and could be tested for potentially identifying patients with a favorable risk/benefit profile for antithrombotic therapy with warfarin.

Quality of anticoagulation control in preventing adverse events in patients with heart failure in sinus rhythm: Warfarin versus Aspirin in Reduced Cardiac Ejection Fraction trial substudy.

BACKGROUND: The aim of this study is to examine the relationship between time in the therapeutic range (TTR) and clinical outcomes in heart failure patients in sinus rhythm treated with warfarin. METHODS AND RESULTS: We used data from the Warfarin versus Aspirin in Reduced Cardiac Ejection Fraction (WARCEF) trial to assess the relationship of TTR with the WARCEF primary outcome (ischemic stroke, intracerebral hemorrhage, or death), with death alone, ischemic stroke alone, major hemorrhage alone, and net clinical benefit (primary outcome and major hemorrhage combined). Multivariable Cox models were used to examine how the event risk changed with TTR and to compare the high TTR, low TTR, and aspirin-treated patients, with TTR being treated as a time-dependent covariate. A total of 2217 patients were included in the analyses; among whom 1067 were randomized to warfarin and 1150 were randomized to aspirin. The median (interquartile range) follow-up duration was 3.6 (2.0-5.0) years. Mean (±SD) age was 61±11.3 years, with 80% being men. The mean (±SD) TTR was 57% (±28.5%). Increasing TTR was significantly associated with reduction in primary outcome (adjusted P<0.001), death alone (adjusted P=0.001), and improved net clinical benefit (adjusted P<0.001). A similar trend was observed for the other 2 outcomes, but significance was not reached (adjusted P=0.082 for ischemic stroke and adjusted P=0.109 for major hemorrhage). CONCLUSIONS: In patients with heart failure in sinus rhythm, increasing TTR is associated with better outcome and improved net clinical benefit. Patients in whom good quality anticoagulation can be achieved may benefit from the use of anticoagulants. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT00041938.

Cognitive function in ambulatory patients with systolic heart failure: insights from the warfarin versus aspirin in reduced cardiac ejection fraction (WARCEF) trial.

We sought to determine whether cognitive function in stable outpatients with heart failure (HF) is affected by HF severity. A retrospective, cross-sectional analysis was performed using data from 2, 043 outpatients with systolic HF and without prior stroke enrolled in the Warfarin versus Aspirin in Reduced Cardiac Ejection Fraction (WARCEF) Trial. Multivariable regression analysis was used to assess the relationship between cognitive function measured using the Mini-Mental Status Exam (MMSE) and markers of HF severity (left ventricular ejection fraction [LVEF], New York Heart Association [NYHA] functional class, and 6-minute walk distance). The mean (SD) for the MMSE was 28.6 (2.0), with 64 (3.1%) of the 2,043 patients meeting the cut-off of MMSE <24 that indicates need for further evaluation of cognitive impairment. After adjustment for demographic and clinical covariates, 6-minute walk distance (ß-coefficient 0.002, p<0.0001), but not LVEF or NYHA functional class, was independently associated with the MMSE as a continuous measure. Age, education, smoking status, body mass index, and hemoglobin level were also independently associated with the MMSE. In conclusion, six-minute walk distance, but not LVEF or NYHA functional class, was an important predictor of cognitive function in ambulatory patients with systolic heart failure.

Recurrent stroke in the warfarin versus aspirin in reduced cardiac ejection fraction (WARCEF) trial.

BACKGROUND AND PURPOSE: WARCEF randomized 2,305 patients in sinus rhythm with ejection fraction (EF) ≤ 35% to warfarin (INR 2.0-3.5) or aspirin 325 mg. Warfarin reduced the incident ischemic stroke (IIS) hazard rate by 48% over aspirin in a secondary analysis. The IIS rate in heart failure (HF) is too low to warrant routine anticoagulation but epidemiologic studies show that prior stroke increases the stroke risk in HF. In this study, we explore IIS rates in WARCEF patients with and without baseline stroke to look for risk factors for IIS and determine if a subgroup with an IIS rate high enough to give a clinically relevant stroke risk reduction can be identified. METHODS: We compared potential stroke risk factors between patients with baseline stroke and those without using the exact conditional score test for Poisson variables. We looked for risk factors for IIS, by comparing IIS rates between different risk factors. For EF we tried cut-off points of 10, 15 and 20%. The cut-off point 15% was used as it was the highest EF that was associated with a significant increase in IIS rate. IIS and EF strata were balanced as to warfarin/aspirin assignment by the stratified randomized design. A multiple Poisson regression examined the simultaneous effects of all risk factors on IIS rate. IIS rates per hundred patient years (/100 PY) were calculated in patient groups with significant risk factors. Missing values were assigned the modal value. RESULTS: Twenty of 248 (8.1%) patients with baseline stroke and 64 of 2,048 (3.1%) without had IIS. IIS rate in patients with baseline stroke (2.37/100 PY) was greater than patients without (0.89/100 PY) (rate ratio 2.68, p < 0.001). Fourteen of 219 (6.4%) patients with ejection fraction (EF) <15% and 70 of 2,079 (3.4%) with EF ≥ 15% had IIS. In the multiple regression analysis stroke at baseline (p < 0.001) and EF <15% vs. ≥ 15% (p = 0.005) remained significant predictors of IIS. IIS rate was 2.04/100 PY in patients with EF <15% and 0.95/100 PY in patients with EF ≥ 15% (p = 0.009). IIS rate in patients with baseline stroke and reduced EF was 5.88/100 PY with EF <15% decreasing to 2.62/100 PY with EF <30%. CONCLUSIONS: In a WARCEF exploratory analysis, prior stroke and EF <15% were risk factors for IIS. Further research is needed to determine if a clinically relevant stroke risk reduction is obtainable with warfarin in HF patients with prior stroke and reduced EF.