Combined anticoagulation and antiplatelet therapy for high-risk patients with atrial fibrillation: a systematic review

BACKGROUND

Previous research suggests uncertainty whether or not there is any additional benefit in adding antiplatelet therapy (APT) to anticoagulation therapy (ACT) in patients with high-risk atrial fibrillation (AF) in terms of reduction in vascular events, including stroke. The existing guidelines acknowledge an increased risk of bleeding associated with such a strategy; however, there is no consensus on the treatment pathway.

OBJECTIVES

To determine, by undertaking a systematic review, if the addition of APT to ACT is beneficial compared with ACT alone in patients with AF who are considered to be at high risk of thromboembolic events (TEs).

DATA SOURCES

Data sources included bibliographic databases {the Cochrane Library [Cochrane Central Register of Controlled Trials (CENTRAL)], MEDLINE, MEDLINE In-Process and Other Non-Indexed Citations, EMBASE, ClinicalTrials.gov, National Institute for Health Research (NIHR) Clinical Research Network Portfolio, Current Controlled Trials (CCT) and the World Health Organization International Clinical Trials Registry Platform (WHO ICTRP)}, reference lists from identified systematic reviews and relevant studies, and contact with clinical experts. Searches were from inception to September 2010 and did not use language restrictions or study design filters.

REVIEW METHODS

Studies of any design were included to evaluate clinical effectiveness, including randomised controlled trials (RCTs), non-randomised comparisons, cohort studies, case series or registries, longitudinal studies, systematic reviews and meta-analyses, and conference abstracts published after 2008. Inclusion criteria consisted of a population with AF, at high-risk of TEs, aged ≥ 18 years, on combined ACT and APT compared with others on ACT alone or ACT plus placebo. Inclusion decisions, assessment of study quality and data extraction were undertaken using methods to minimise bias.

RESULTS

Fifty-three publications were included, reporting five RCTs (11 publications), 18 non-randomised comparisons (24 publications) and 18 publications that reported reviews, which added no further data. There was variation in the population, types and doses of ACT and APT, definitions of outcomes, and length of follow-up between the studies. There was a paucity of directly randomised high-quality RCTs, whereas non-randomised comparisons were found to have significant confounding factors. No studies looked at the effect of ACT plus APT compared with ACT alone on vascular events in patients with AF following acute coronary syndrome (ACS) or percutaneous coronary intervention. In most studies, significant differences in event rates were not seen between the patients on combined therapy compared with those on ACT alone for outcomes such as stroke (including haemorrhagic and ischaemic strokes), rates of transient ischaemic attacks, composite end points of stroke and systemic embolism (SE), SE alone, acute myocardial infarction, mortality (vascular or all cause) or bleeding events. There was conflicting evidence regarding rates of major adverse events consisting of composite end points, although event rates were generally low.

LIMITATIONS

An attempt was made to identify all of the available evidence around the subject despite the dearth of directly randomised studies using a robust review methodology. There was a paucity of directly randomised evidence to undertake a meta-analysis for the merits of one technology over another. The selection criteria were kept necessarily broad with regard to the population, intervention and comparator in order to capture all relevant studies.

CONCLUSIONS

This systematic review suggests that there is still insufficient evidence to advocate a clear benefit of the addition of APT to ACT compared with ACT alone in reducing the risk of vascular events in a population of patients at high risk of TEs resulting from AF. It is recommended that a definitive prospective RCT needs to be undertaken in a population at high risk of atherosclerotic coronary artery and other vascular events in addition to being at high risk of AF-mediated TEs. From the UK context, at the time of writing, any future trial should compare adjusted-dose warfarin [international normalised ratio (INR) 2.0-3.0] plus aspirin (75-325 mg) with adjusted-dose warfarin (INR 2.0-3.0). However, given the emergence of newer anticoagulation agents (dabigatran, rivaroxaban and apixaban) this prioritisation may need to be revisited in the future to reflect current best clinical practice.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Patient's values and preferences for stroke prevention in atrial fibrillation: balancing stroke and bleeding risk with oral anticoagulation

Note: The review process for this editorial was handled by Christian Weber, Editor in Chief.

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.

Adjusted prognostic association of depression following myocardial infarction with mortality and cardiovascular events: individual patient data meta-analysis

BACKGROUND

The association between depression after myocardial infarction and increased risk of mortality and cardiac morbidity may be due to cardiac disease severity.

AIMS

To combine original data from studies on the association between post-infarction depression and prognosis into one database, and to investigate to what extent such depression predicts prognosis independently of disease severity.

METHOD

An individual patient data meta-analysis of studies was conducted using multilevel, multivariable Cox regression analyses.

RESULTS

Sixteen studies participated, creating a database of 10 175 post-infarction cases. Hazard ratios for post-infarction depression were 1.32 (95% CI 1.26-1.38, P<0.001) for all-cause mortality and 1.19 (95% CI 1.14-1.24, P<0.001) for cardiovascular events. Hazard ratios adjusted for disease severity were attenuated by 28% and 25% respectively.

CONCLUSIONS

The association between depression following myocardial infarction and prognosis is attenuated after adjustment for cardiac disease severity. Still, depression remains independently associated with prognosis, with a 22% increased risk of all-cause mortality and a 13% increased risk of cardiovascular events per standard deviation in depression z-score.

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.

Cannabinoid-1 receptors in the mouse ventral pallidum are targeted to axonal profiles expressing functionally opposed opioid peptides and contacting N-acylphosphatidylethanolamine-hydrolyzing phospholipase D terminals

The ventral pallidum (VP) is a major recipient of inhibitory projections from nucleus accumbens (Acb) neurons that differentially express the reward (enkephalin) and aversion (dynorphin)-associated opioid peptides. The cannabinoid-1 receptor (CB1R) is present in Acb neurons expressing each of these peptides, but its location in the VP is not known. To address this question, we used electron microscopic dual immunolabeling of the CB1R and either dynorphin 1-8 (Dyn) or Met(5)-enkephalin (ME) in the VP of C57BL/6J mice, a species in which CB1R gene deletion produces a reward deficit. We also used similar methods to determine the relationship between the CB1R and N-acylphosphatidylethanolamine (NAPE)-hydrolyzing phospholipase D (NAPE-PLD), an anandamide-synthesizing enzyme located presynaptically in other limbic brain regions. CB1R-immunogold was principally localized to cytoplasmic endomembranes and synaptic or extrasynaptic plasma membranes of axonal profiles, but was also affiliated with postsynaptic membrane specializations in dendrites. The axonal profiles included many single CB1R-labeled axon terminals as well as terminals containing CB1R-immunogold and either Dyn or ME immunoreactivity. Dually labeled terminals comprised 26% of all Dyn- and 17% of all ME-labeled axon terminals. Both single- and dual-labeled terminals formed mainly inhibitory-type synapses, but almost 16% of these terminals formed excitatory synapses. Approximately 60% of the CB1R-labeled axonal profiles opposed or converged with axon terminals containing NAPE-PLD immunoreactivity. We conclude that CB1Rs in the mouse VP have subcellular distributions consistent with on demand activation by endocannabinoids that can regulate the release of functionally opposed opioid peptides and also modulate inhibitory and excitatory transmission.

A comparison of risk stratification schemes for stroke in 79,884 atrial fibrillation patients in general practice

BACKGROUND

Anticoagulation management of patients with atrial fibrillation (AF) should be tailored individually on the basis of ischemic stroke risk. The objective of this study was to compare the predictive ability of 15 published stratification schemes for stroke risk in actual clinical practice in the UK.

METHODS

AF patients aged ≥ 18 years in the General Practice Research Database, which contains computerized medical records, were included. The c-statistic was estimated to determine the predictive ability for stroke for each scheme. Outcomes included stroke, hospitalizations for stroke, and death resulting from stroke (as recorded on death certificates).

RESULTS

The study cohort included 79,844 AF patients followed for an average of 4 years (average of 2.4 years up to the start of warfarin therapy). All risk schemes had modest discriminatory ability in AF patients, with c-statistics for predicting events ranging from 0.55 to 0.69 for strokes recorded by the general practitioner or in hospital, from 0.56 to 0.69 for stroke hospitalizations, and from 0.56 to 0.78 for death resulting from stroke as reported on death certificates. The proportion of patients assigned to individual risk categories varied widely across the schemes, with the proportion categorized as moderate risk ranging from 12.7% (CHA(2) DS(2)-VASc) to 61.5% (modified CHADS(2)). Low-risk subjects were truly low risk (with annual stroke events < 0.5%) with the modified CHADS(2), National Institute for Health and Clinical Excellence and CHA(2) DS(2) -VASc schemes.

CONCLUSION

Current published risk schemes have modest predictive value for stroke. A new scheme (CHA(2) DS(2) -VASc) may discriminate those at truly low risk and minimize classification of subjects as intermediate/moderate risk. This approach would simplify our approach to stroke risk stratification and improve decision-making for thromboprophylaxis in patients with AF.

Short-term effects of screening for cardiovascular risk in the deaf community: a pilot study

There is limited information on the risk of cardiovascular disease amongst the Deaf community. Given that the access of Deaf people to mainstream health promotion is likely to be hindered by language barriers, we were interested to assess the short-term impact of cardiovascular health promotion within this group. Using a pilot study we investigated changes in cardiovascular risk factors amongst Deaf people identified to be at high cardiovascular risk, who received standard health promotion by a medical team specializing in cardiovascular health promotion. The short-term impact of cardiovascular health promotion in this group did not reduce estimates of cardiovascular risk. The reasons for this are likely to relate to the design and delivery of health promotion to Deaf people, which deserves further study.

Differential glutamate AMPA-receptor plasticity in subpopulations of VTA neurons in the presence or absence of residual cocaine: implications for the development of addiction

Cocaine-induced plasticity of mesocorticolimbic dopamine (DA) neurons, originating in the ventral tegmental area (VTA), persists in the absence of cocaine and may contribute to both drug-craving and relapse. Glutamate AMPA receptors (AMPARs) in these neurons are implicated in this plasticity. However, there is no ultrastructural evidence that the absence of cocaine following repeated administrations affects the critical surface/synaptic availability of AMPAR GluR1 subunits in either DA or non-DA, putative GABAergic neurons within the VTA. To assess this, we used electron microscopic immunolabeling in the VTA of adult male mice sacrificed at 30 min or 72 h after receiving the final of six (15 mg/kg) cocaine injections, a dosing paradigm that resulted in development of locomotor sensitization. At each time point, both cocaine- and saline-injected mice showed AMPAR GluR1 immunogold labeling in somatodendritic profiles, many of which contained immunoperoxidase labeling for the DA-synthesizing enzyme, tyrosine hydroxylase (TH). At 30 min after the last injection, when cocaine was systemically present, only the non-TH labeled dendrites showed a significant increase in the synaptic/plasmalemmal density of GluR1 immunogold particles. At 72 h, when systemic cocaine was depleted, synaptic GluR1 labeling was greatly enhanced in TH-containing dendrites throughout the VTA and in non-TH dendrites of the limbic-associated paranigral VTA. Our results demonstrate that systemic cocaine produces GluR1 trafficking specifically in non-DA neurons of the VTA, which may subsequently contribute to the abstinent-induced enhancement of AMPA receptor synaptic transmission in mesocorticolimbic DA neurons leading to heightened drug seeking behavior.

A comparison of risk stratification schemes for stroke in 79,884 atrial fibrillation patients in general practice

BACKGROUND

Anticoagulation management of patients with atrial fibrillation (AF) should be tailored individually on the basis of ischemic stroke risk. The objective of this study was to compare the predictive ability of 15 published stratification schemes for stroke risk in actual clinical practice in the UK.

METHODS

AF patients aged ≥ 18 years in the General Practice Research Database, which contains computerized medical records, were included. The c-statistic was estimated to determine the predictive ability for stroke for each scheme. Outcomes included stroke, hospitalizations for stroke, and death resulting from stroke (as recorded on death certificates).

RESULTS

The study cohort included 79,844 AF patients followed for an average of 4 years (average of 2.4 years up to the start of warfarin therapy). All risk schemes had modest discriminatory ability in AF patients, with c-statistics for predicting events ranging from 0.55 to 0.69 for strokes recorded by the general practitioner or in hospital, from 0.56 to 0.69 for stroke hospitalizations, and from 0.56 to 0.78 for death resulting from stroke as reported on death certificates. The proportion of patients assigned to individual risk categories varied widely across the schemes, with the proportion categorized as moderate risk ranging from 12.7% (CHA(2) DS(2)-VASc) to 61.5% (modified CHADS(2)). Low-risk subjects were truly low risk (with annual stroke events < 0.5%) with the modified CHADS(2), National Institute for Health and Clinical Excellence and CHA(2) DS(2) -VASc schemes.

CONCLUSION

Current published risk schemes have modest predictive value for stroke. A new scheme (CHA(2) DS(2) -VASc) may discriminate those at truly low risk and minimize classification of subjects as intermediate/moderate risk. This approach would simplify our approach to stroke risk stratification and improve decision-making for thromboprophylaxis in patients with AF.

Acute and chronic cocaine differentially alter the subcellular distribution of AMPA GluR1 subunits in region-specific neurons within the mouse ventral tegmental area

Cocaine administration increases AMPA GluR1 expression and receptor-mediated activation of the ventral tegmental area (VTA). Functionality is determined, however, by surface availability of these receptors in transmitter- and VTA-region-specific neurons, which may also be affected by cocaine. To test this hypothesis, we used electron microscopic immunolabeling of AMPA GluR1 subunits and tyrosine hydroxylase (TH), the enzyme needed for dopamine synthesis, in the cortical-associated parabrachial (PB) and in the limbic-associated paranigral (PN) VTA of adult male C57BL/6 mice receiving either a single injection (acute) or repeated escalating-doses for 14 days (chronic) of cocaine. Acute cocaine resulted in opposing VTA-region-specific changes in TH-containing dopaminergic dendrites. TH-labeled dendrites within the PB VTA showed increased cytoplasmic GluR1 immunogold particle density consistent with decreased AMPA receptor-mediated glutamatergic transmission. Conversely, TH-labeled dendrites within the PN VTA showed greater surface expression of GluR1 with increases in both synaptic and plasmalemmal GluR1 immunogold density after a single injection of cocaine. These changes diminished in both VTA subregions after chronic cocaine administration. In contrast, non-TH-containing, presumably GABAergic dendrites showed VTA-region-specific changes only after repeated cocaine administration such that synaptic GluR1 decreased in the PB, but increased in the PN VTA. Taken together, these findings provide ultrastructural evidence suggesting that chronic cocaine not only reverses the respective depression and facilitation of mesocortical (PB) and mesolimbic (PN) dopaminergic neurons elicited by acute cocaine, but also differentially affects synaptic availability of these receptors in non-dopaminergic neurons of each region. These adaptations may contribute to increased cocaine seeking/relapse and decreased reward that is reported with chronic cocaine use.

Subcellular plasticity of the corticotropin-releasing factor receptor in dendrites of the mouse bed nucleus of the stria terminalis following chronic opiate exposure

Chronic opiate administration alters the expression levels of the stress-responsive peptide, corticotropin-releasing factor (CRF), in the bed nucleus of the stria terminalis (BNST). This brain region contains CRF receptors that drive drug-seeking behavior exacerbated by stress. We used electron microscopy to quantitatively compare immunolabeling of the corticotropin-releasing factor receptor (CRFr) and CRF in the anterolateral bed nucleus of the stria terminalis (BSTal) of mice injected with saline or morphine in escalating doses for 14 days. We also compared the results with those in non-injected control mice. The tissue was processed for CRFr immunogold and CRF immunoperoxidase labeling. The non-injected controls had a significantly lower plasmalemmal density of CRFr immunogold particles in dendrites compared with mice receiving saline, but not those receiving morphine, injections. Compared with saline, however, mice receiving chronic morphine showed a significantly lower plasmalemmal, and greater cytoplasmic, density of CRFr immunogold in dendrites. Within the cytoplasmic compartment of somata and dendrites of the BSTal, the proportion of CRFr gold particles associated with mitochondria was three times as great in mice receiving morphine compared with saline. This subcellular distribution is consistent with morphine,- and CRFr-associated modulation of intracellular calcium release or oxidative stress. The between-group changes occurred without effect on the total number of dendritic CRFr immunogold particles, suggesting that chronic morphine enhances internalization or decreases delivery of the CRFr to the plasma membrane, a trafficking effect that is also affected by the stress of daily injections. In contrast, saline and morphine treatment groups showed no significant differences in the total number of CRF-immunoreactive axon terminals, or the frequency with which these terminals contacted CRFr-containing dendrites. This suggests that morphine does not influence axonal availability of CRF in the BSTal. The results have important implications for drug-associated adaptations in brain stress systems that may contribute to the motivation to continue drug use during dependence.

Evidence that high von Willebrand factor and low ADAMTS-13 levels independently increase the risk of a non-fatal heart attack

BACKGROUND

A disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13 (ADAMTS-13) may influence von Willebrand factor (VWF) levels and consequently the risk of myocardial infarction (MI). Moreover, ADAMTS-13 influences hemostatic plug formation in mouse models. We therefore studied their associations in the Glasgow MI Study (GLAMIS).

METHODS AND RESULTS

We measured ADAMTS-13 and VWF antigen levels by ELISAs in stored plasma from a case-control study of 466 MI cases and 484 age- and sex-matched controls from the same north Glasgow population. There was no correlation between ADAMTS-13 and VWF levels in cases or controls. ADAMTS-13 levels correlated positively with serum cholesterol and triglycerides and body mass index, and negatively with high-density lipoprotein-cholesterol. VWF levels correlated with age, fibrinogen and C-reactive protein. In multivariable analyses including risk factors, VWF correlated positively with risk of MI, and ADAMTS-13 correlated negatively with risk of MI. These associations were independent of each other. The association of ADAMTS-13 with risk of MI was observed only in multivariable analysis.

CONCLUSIONS

VWF and ADAMTS-13 levels were not associated in this study, and showed associations with MI risk in opposite directions but of similar strength. The association of ADAMTS-13 with MI is influenced by lipid levels, and consequently requires further investigation.