Atrial fibrillation as a risk factor for cognitive impairment: a semi-systematic review

It is unclear if atrial fibrillation (AF) is an independent risk factor for cognitive impairment. This review evaluates the available evidence and provides an overview of the association between AF and cognitive function. Electronic database searches, January 1990 to December 2012, identified 271 studies comparing the incidence of cognitive impairment and/or dementia in patients with/without AF. Cognitive function was diagnosed by a physician using the mini-mental state examination (MMSE) or other established diagnostic criteria. Studies with <20 participants and without direct comparison to controls in sinus rhythm were excluded. There were no restrictions on the basis of age, language or study design. Full texts of 11 studies were obtained. Eight studies (three cross-sectional, two case-control and three prospective cohorts) reported an association between cognitive decline and AF. Among cross-sectional studies, patients with AF had a 1.7 (95% CI 1.2-2.5) to 3.3 (95% CI 1.6-6.5) greater risk of cognitive impairment, and a 2.3-fold (95% CI 1.4-3.7) increased risk of dementia, compared to patients in sinus rhythm. There was marked heterogeneity in the design, size and quality of studies and reporting of the data which precluded formal meta-analysis. Eight studies reported an association between AF and cognitive impairment and/or dementia, but the magnitude of risk varied. Further large-scale prospective studies are needed to establish whether AF is a risk factor for cognitive decline, utilizing objective measures of cognitive function and neuropsychological testing, and to investigate the potential benefit of anticoagulation on reducing cognitive impairment and development of dementia.

Retinal vein and artery occlusions: a risk factor for stroke in atrial fibrillation

BACKGROUND

Retinal vascular occlusions may constitute an independent risk factor for stroke in patients with atrial fibrillation.

METHODS

We performed a retrospective study on a nationwide cohort with atrial fibrillation from 1997 to 2008. The rate of stroke/systemic thromboembolism (TE)/transitory ischemic attack (TIA) was determined for atrial fibrillation patients with and without a history of retinal vascular occlusion. A Cox regression analysis, adjusted for risk factors and medications, was performed to determine the independent predictive value of retinal arterial or venous occlusion for the risk of ischemic stroke, TE or TIA in atrial fibrillation patients.

RESULTS

We included 87 202 patients with non-valvular atrial fibrillation. At baseline, a history of retinal arterial occlusion was diagnosed in 224 patients (0.26%) and a history of retinal venous occlusion in 361 (0.41%). Patients without retinal occlusion had a rate of stroke/TE/TIA of 4.52 (95% confidence interval [CI] 4.44-4.60). For patients with retinal arterial occlusion, the rate of stroke/TE/TIA was 8.16 (95% CI 6.35-10.49) per 100 person-years, and for patients with retinal venous occlusion it was 7.28 (95% CI 5.93-8.94) per 100 person-years. In multivariate analysis, both retinal arterial occlusions (hazard ratio [HR] 1.39, 95% CI 1.08-1.79) and retinal venous occlusions (HR 1.26, 95% CI 1.02-1.54) were associated with an increased risk of future stroke/TE/TIA.

CONCLUSIONS

A history of retinal arterial or retinal venous occlusion is associated with an increased risk of stroke/TE/TIA in patients with atrial fibrillation. Thus, prior retinal vascular occlusion may be considered as a previous thromboembolic event when evaluating stroke risk in patients with atrial fibrillation.

Routine versus aggressive upstream rhythm control for prevention of early atrial fibrillation in heart failure: background, aims and design of the RACE 3 study

Background

Rhythm control for atrial fibrillation (AF) is cumbersome because of its progressive nature caused by structural remodelling. Upstream therapy refers to therapeutic interventions aiming to modify the atrial substrate, leading to prevention of AF.

Objective

The Routine versus Aggressive upstream rhythm Control for prevention of Early AF in heart failure (RACE 3) study hypothesises that aggressive upstream rhythm control increases persistence of sinus rhythm compared with conventional rhythm control in patients with early AF and mild-to-moderate early systolic or diastolic heart failure undergoing electrical cardioversion.

Design

RACE 3 is a prospective, randomised, open, multinational, multicenter trial. Upstream rhythm control consists of angiotensin converting enzyme inhibitors and/or angiotensin receptor blockers, mineralocorticoid receptor antagonists, statins, cardiac rehabilitation therapy, and intensive counselling on dietary restrictions, exercise maintenance, and drug adherence. Conventional rhythm control consists of routine rhythm control therapy without cardiac rehabilitation therapy and intensive counselling. In both arms, every effort is made to keep patients in the rhythm control strategy, and ion channel antiarrhythmic drugs or pulmonary vein ablation may be instituted if AF relapses. Total inclusion will be 250 patients. If upstream therapy proves to be effective in improving maintenance of sinus rhythm, it could become a new approach to rhythm control supporting conventional pharmacological and non-pharmacological rhythm control.

The impact of atherosclerotic vascular disease in predicting a stroke, thromboembolism and mortality in atrial fibrillation patients: a systematic review

BACKGROUND

Atrial fibrillation (AF) is commonly associated with vascular disease. Although atherosclerotic vascular disease (for example, defined as a myocardial infarction (MI), complex aortic plaque and peripheral arterial disease) has been proposed as a risk factor for a stroke, the co-existence of the two diseases increases the risk of future cardiovascular events. The objective of this study was to conduct a systematic review to assess the impact of atherosclerotic vascular disease on the primary end-point of a stroke, thromboembolism or mortality, in patients with AF.

METHODS

Literature searches were performed electronically, to identify studies published between January 1990and July 2012 examining stroke and thromboembolism in relation to AF and atherosclerotic vascular disease. Nineteen articles satisfied the pre-inclusion criteria. The bibliographies were subsequently screened to retrieve further relevant studies for this review.

RESULTS

Peripheral arterial disease significantly increased the stroke risk in all 10 observational studies, within a reported risk range of 1.3- to 2.5-fold. Complex aortic plaque on the descending aorta, as identified by trans-oesophageal echocardiography, was also a significant risk factor. Although a prior myocardial infarction (MI) was validated as a significant predictor of the primary end-point amongst five of the six studies, there was a degree of heterogeneity, owing to the marked difference in population sizes and the use of antithrombotic regimens between studies.

CONCLUSION

Atherosclerotic vascular disease (e.g. peripheral arterial disease, complex aortic plaque and prior MI) are significant predictors of a stroke, thromboembolism and mortality in subjects with AF.

Upper limb arterial thromboembolism: a systematic review on incidence, risk factors, and prognosis, including a meta-analysis of risk-modifying drugs

OBJECTIVES

The aim of this review is to focus on risk factors, risk-modifying drugs and prognosis for upper limb arterial thromboembolism, and the relationship between upper limb arterial thromboembolism and atrial fibrillation (AF).

METHODS

We searched MEDLINE for studies on the epidemiology of upper limb thromboembolism from 1965 to June 2012. We also searched for contemporary, phase III randomized trial data on systemic (non-stroke) thromboembolism comparing warfarin with new oral anticoagulants (OACs) in patients with atrial fibrillation published after the year 1999.

RESULTS

The incidence of upper limb thromboembolectomy was 3.3 per 100 000 person-years among men and 5.2 per 100 000 person-years among women; the risk of limb amputation, stroke and death after thromboembolectomy was increased. There was an increased risk of thromboembolectomy of the upper limb in patients with AF diagnosed with hypertension (hazard ratio [HR] 2.2-2.9), myocardial infarction (HR 2.9-3.9), heart failure (HR 1.6-1.9), and stroke (HR 2.2-3.8). For those diagnosed with diabetes mellitus, the risk was non-significantly increased by 1.2-1.4. Females had a 1.8-fold (95% confidence interval [CI] 1.5-2.3) fold increased risk of thromboembolectomy as compared with men. The risk reduction for systemic embolism with new OACs as compared with warfarin in patients with AF is similar to that seen with warfarin (odds ratio 0.79, 95% CI 0.38-1.64).

CONCLUSIONS

Age, female sex, AF, hypertension, diabetes, myocardial infarction, heart failure and stroke are most common risk factors for thromboembolectomy of the upper limb. The availability of new OACs holds promise for reducing the risk of systemic thromboembolism, but specific data are still limited.

Recommendations for thromboprophylaxis in the 2012 focused update of the ESC guidelines on atrial fibrillation: a commentary

The objective of this article is to provide a commentary on the recommendations for stroke prevention from the 2012 focused update of the European Society of Cardiology guidelines on the management of atrial fibrillation and the evidence (or lack of it) supporting these recommendations. These guidelines strongly advocate a major clinical practice shift towards initially focusing on the identification of 'truly low risk' patients who do not need any antithrombotic therapy. After this initial decision-making step, effective stroke prevention - that is, oral anticoagulation therapy (whether as well-controlled adjusted dose warfarin or with one of the novel oral anticoagulants) - could be offered to patients with atrial fibrillation with ≥ 1 stroke risk factors. The 2012 focused update guideline also provides additional guidance on advances in stroke and bleeding risk assessment that are evident since publication of the 2010 guideline, as well as recommendations on the use of the novel oral anticoagulants and the left atrial appendage occlusion devices that have been increasingly used in European clinical practice over the last 2 years.

TLR4 expression on monocyte subsets in myocardial infarction

BACKGROUND

Monocyte toll-like receptor 4 (TLR4) has been implicated in the pathogenesis of atherosclerosis with increased levels in myocardial infarction. The aim of this study was to assess the numbers of TLR4(+) monocytes in each monocyte subset in MI, the expression of TLR4 and association with markers of monocyte activation, inflammation, myocardial damage and postmyocardial infarction (MI) cardiac contractility.

METHODS

Surface expression of TLR4 and numbers of TLR4-expressing monocytes were quantified by flow cytometry of venous blood in 50 patients with ST-elevation MI (STEMI), 48 with non-STEMI (NSTEMI) and 40 with stable coronary artery disease (CAD). These parameters were measured on days 1, 3, 7 and 30 post-MI in STEMI patients. Three monocyte subsets were defined as CD14(++) CD16(-) CCR2(+) (Mon1), CD14(++) CD16(+) CCR2(+) (Mon2) and CD14(+) CD16(++) CCR2(-) (Mon3). Plasma inflammatory cytokines were assessed using cytometric bead arrays.

RESULTS

There was a significant increase in counts of TLR4(+) Mon1 and Mon2 in STEMI patients and TLR4(+) Mon2 in NSTEMI patients compared with controls with CAD. Monocyte TLR4(+) expression was similar between the groups, and was not changed during follow-up in STEMI patients. Plasma interleukin-6 (IL6) levels correlated positively with TLR4(+) Mon2 count (r = 0.54, P < 0.001), but negatively with TLR4 expression on Mon2 (r = -0.33, P = 0.021).

CONCLUSION

Following treatment of acute MI, TLR4 expression by individual monocyte subsets is unchanged. An increase in TLR4(+) Mon1 and Mon2 count in patients with STEMI and TLR(+) Mon2 count in those with NSTEMI is due to an increase in monocyte subset count and not to changes in TLR4 expression. Monocyte counts but not TLR4 expression correlate positively with plasma IL6 levels. We suggest that TLR4 expression may not be a reliable marker of monocyte activation in MI.