Ischemic stroke and atrial fibrillation. A clinical study

Factors associated with ischemic stroke on therapeutic anticoagulation in patients with nonvalvular atrial fibrillation

PURPOSE

In this study, we investigated the stroke mechanism and the factors associated with ischemic stroke in patients with nonvalvular atrial fibrillation (NVAF) who were on optimal oral anticoagulation with warfarin.

MATERIALS AND METHODS

This was a multicenter case-control study. The cases were consecutive patients with NVAF who developed cerebral infarction or transient ischemic attack (TIA) while on warfarin therapy with an international normalized ratio (INR) ≥2 between January 2007 and December 2011. The controls were patients with NVAF without ischemic stroke who were on warfarin therapy for more than 1 year with a mean INR ≥2 during the same time period. We also determined etiologic mechanisms of stroke in cases.

RESULTS

Among 3569 consecutive patients with cerebral infarction or TIA who had NVAF, 55 (1.5%) patients had INR ≥2 at admission. The most common stroke mechanism was cardioembolism (76.0%). Multivariate analysis demonstrated that smoking and history of previous ischemic stroke were independently associated with cases. High CHADS2 score (≥3) or CHA₂DS₂-VASc score (≥5), in particular, with previous ischemic stroke along with ≥1 point of other components of CHADS₂ score or ≥3 points of other components of CHA₂DS₂-VASc score was a significant predictor for development of ischemic stroke.

CONCLUSION

NVAF patients with high CHADS₂/CHA₂DS₂-VASc scores and a previous ischemic stroke or smoking history are at high risk of stroke despite optimal warfarin treatment. Some other measures to reduce the risk of stroke would be necessary in those specific groups of patients.

The Link between Atrial Fibrillation and Stroke in Women

Atrial fibrillation (AF) is the most common clinically significant cardiac arrhythmia. The most serious complication of AF is thromboembolic stroke. The individual risk of stroke in the setting of AF varies. Several clinical factors have been identified as independent predictors of stroke in AF, including prior stroke, age, hypertension and diabetes. The bulk of available data identifies female gender as another independent predictor of stroke risk in AF. In this article, we review the link between AF and an elevated stroke risk in women, explore the potential pathophysiologic basis for this association and examine the data regarding the effectiveness of anticoagulation in reducing this risk.

Identifying patients at high risk for stroke despite anticoagulation: a comparison of contemporary stroke risk stratification schemes in an anticoagulated atrial fibrillation cohort

BACKGROUND AND PURPOSE

The risk of stroke in patients with atrial fibrillation (AF) is not homogeneous, and various clinical risk factors have informed the development of stroke risk stratification schemes (RSS). Among anticoagulated cohorts, the emphasis should be on the identification of patients who remain at high risk for stroke despite anticoagulation.

METHODS

We investigated predictors of thromboembolism (TE) risk in an anticoagulated AF clinical trial cohort (n = 7329 subjects) and tested the predictive value of contemporary RSS in this cohort: CHADS₂, Framingham, NICE 2006, American College of Cardiology/American Heart Association/European Society of Cardiology 2006, the 8th American College of Chest Physicians guidelines and the CHA₂DS₂-VASc schemes.

RESULTS

On multivariate analysis, significant predictors of TE were stroke/TIA (hazard ratio [HR], 2.24; P < 0.001), age 75 years or older (HR, 1.77; P = 0.0002), coronary artery disease (HR, 1.52; P = 0.0047), and smoking (HR, 2.10; P = 0.0005), whereas reported alcohol use (HR, 0.70; P = 0.02) was protective. Comparison of contemporary RSS demonstrated variable classification of AF patients into risk strata, although c-statistics for TE were broadly similar among the RSS tested and varied between 0.575 (NICE 2006) and 0.647 (CHA₂DS₂-VASc). CHA₂DS₂-VASc classified 94.2% as being at high risk, whereas most other RSS categorized two-thirds as being at high risk. Of the 184 TE events, 181 (98.4%) occurred in patients identified as being at high risk by the CHA₂DS₂-VASc schema. There was a stepwise increase in TE with increasing CHA₂DS₂-VASc score (P (trend) < 0.0001), which had the highest HR (3.75) among the tested schemes. The negative predictive value (ie, the percent categorized as "not high risk" actually being free from TE) for CHA₂DS₂-VASc was 99.5%.

CONCLUSIONS

Coronary artery disease and smoking are additional risk factors for TE in anticoagulated AF patients, whereas alcohol use appears protective. Of the contemporary stroke RSS, the CHA₂DS₂-VASc scheme correctly identified the greatest proportion of AF patients at high risk, despite the similar predictive ability of most RSS evidenced by the c-statistic.

Functional outcome in stroke patients with atrial fibrillation

OBJECTIVES

To identify the prevalence of atrial fibrillation (AF) in a sample of stroke patients and to evaluate the impact of AF on patient clinical characteristics and functional outcome.

DESIGN

A retrospective case-comparison study.

SETTING

University-affiliated rehabilitation centers.

PARTICIPANTS

One hundred ninety-six of 231 consecutive stroke patients admitted to inpatient rehabilitation units were evaluated during the rehabilitation period.

MAIN OUTCOME MEASURES

Characteristics of cerebral lesions, patient demographic features, disease duration, length of hospital stay (LOS), risk factors for stroke, and functional status at admission and at discharge were assessed and compared in patients with and without AF. Functional Independence Measure (FIM) and Adapted Patient Evaluation Conference System (APECS) were used to evaluate functional status.

RESULTS

AF was diagnosed in 41 (20.1%) patients. Patients who had AF were more likely to have ischemic cerebral lesions. There were no significant differences between the AF and non-AF groups with regard to mean age, LOS, and disease duration. Ischemic and valvular heart disease were more common in patients with AF. Based on FIM and APECS scores, both initial and discharge disability were more severe in patients with AF. In a multivariate model, AF was a negative prognostic factor for functional outcome in stroke patients.

CONCLUSION

AF is not only associated with increased risk of stroke, but also with markedly greater disability in stroke patients. Factors such as size and type of cerebral lesions, stroke severity, comorbid conditions, and impact of AF on systemic and cerebral circulation can influence stroke recovery.

The risk of hospitalization for ischemic stroke among older adults

OBJECTIVES

The purpose of this study was to identify risk factors for stroke and to estimate their relative importance in a large, nationally representative sample of very old men and women.

METHODS

The study was designed as a secondary analysis of the Longitudinal Study on Aging. Baseline (1984) in-person interview data were linked to Medicare hospitalization records for 1984 to 1991. Participants were 6,071 noninstitutionalized adults 70 years old or older at baseline. Hospitalization for ischemic stroke was defined as having one or more episodes with a primary discharge diagnosis containing ICD-9-CM codes of 433.0-434.9, 436, and 437.0-437.1. Multivariable proportional hazards regression was used to estimate the risks associated with previously identified epidemiologic factors.

RESULTS

Five hundred and three persons (8.3%) had at least one primary discharge diagnosis of ischemic stroke. In descending order of importance-based on the partial r statistics associated with their adjusted hazards ratios (AHRs), the salient risk factors were having a previous history of stroke (AHR = 2.86), age (AHR = 1.04 per year), diabetes (AHR = 1.78), male gender (AHR = 1.42), lower body limitations (AHR = 1.09 per limitation), arthritis (AHR = 0.74), hypertension (AHR = 1.29), and poverty (AHR = 1.33).

CONCLUSION

Patients presenting with the high risk factors identified in this study should be considered for further evaluation and monitoring. Current protocols for the therapeutic management of these higher risk patients should be considered, and compliance should be encouraged.