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Background: The association between atrial fibrillation and dementia has been described. Whether a specific association exists between atrial fibrillation and Alzheimer's disease remains uncertain. This study aims to assess the association between atrial fibrillation and Alzheimer's disease through a systematic review and meta-analysis of the literature., Methods: An exhaustive search of electronic databases up to October 2018 was conducted. Studies that identified patients with and without atrial fibrillation as well as patients with and without Alzheimer's disease and reported results of at least one relevant outcome, including hazard ratio of the association between atrial fibrillation and Alzheimer's disease were included in this analysis. The hazard ratios and their confidence interval were then pooled using a DerSimonian and Laird random effects model., Results: Six studies enrolling a total of 56 370 patients were included. At baseline, the mean or median ages ranged from 50 to 78 years with a subsequent follow-up of 3 to 25 years. The random-effect pooled analysis showed a hazard ratio of 1.30 (95% confidence interval 1.01-1.59) and the heterogeneity was not significant, I 48.1%. All of the included studies were rated as good quality., Conclusion: Pooled analysis suggest that patients with atrial fibrillation may be exposed to an increased risk of developing new onset of Alzheimer's disease. Given the relevant clinical implications, further studies are required to corroborate these findings.

Background: Postoperative atrial fibrillation (POAF) is a frequent occurrence after noncardiac surgery. It remains unclear whether POAF is associated with an increased risk of major adverse events. We aimed to elucidate the risk of stroke, myocardial infarction, and death associated with POAF following noncardiac surgery by a meta-analysis of randomized controlled studies and observational studies., Methods: We searched electronic databases from inception up to August 1, 2019 for all studies that reported stroke or myocardial infarction in adult patients who developed POAF following noncardiac surgery. We used random-effects models to summarize the studies., Results: The final analyses included 28 studies enrolling 2 612 816 patients. At 1-month (10 studies), POAF was associated with an ≈3-fold increase in the risk of stroke (weighted mean 2.1% versus 0.7%; odds ratio [OR], 2.82 [95% CI, 2.15-3.70]; P <0.001). POAF was associated with ≈4-fold increase in the long-term risk of stroke with (weighted mean, 2.0% versus 0.6%; OR, 4.12 [95% CI, 3.32-5.11]; P ≤0.001) in 8 studies with ≥12-month follow-up. There was a significant overall increase in the risk of stroke and myocardial infarction associated with POAF (weighted mean, 2.5% versus 0.9%; OR, 3.44 [95% CI, 2.38-4.98]; P <0.001) and (weighted mean, 12.6% versus 2.7%; OR, 4.02 [95% CI, 3.08-5.24]; P <0.001), respectively. Furthermore, POAF was associated with a 3-fold increase in all-cause mortality at 30 days (weighted mean, 15.0% versus 5.4%; OR, 3.36 [95% CI, 2.13-5.31]; P <0.001)., Conclusions: POAF was associated with markedly higher risk of stroke, myocardial infarction, and all-cause mortality following noncardiac surgery. Future studies are needed to evaluate the impact of optimal cardiovascular pharmacotherapies to prevent POAF and to decrease the risk of major adverse events in these high-risk patients.

Atrial fibrillation (AF) is the most common arrhythmia encountered in clinical practice with implications on long-term outcomes. Metabolic disorders including diabetes mellitus and obesity are independent predictors of atrial fibrillation and present therapeutic targets to reduce both the incidence and duration burden of atrial fibrillation. The presence of pericardial fat in direct contact with cardiac structures, as well the subsequent release of proinflammatory cytokines, may play an important role in this connection. Atrial fibrillation is an independent predictor of cognitive impairment and dementia. While clinical stroke is a major contributor, other factors such as cerebral hypoperfusion and microbleeds play important roles. New evidence suggests that atrial fibrillation and cognitive impairment may be downstream events of atrial cardiomyopathy, which may be caused by several factors including metabolic syndrome, obesity, and obstructive sleep apnea. The mechanisms linking these comorbidities to cognitive impairment are not yet fully elucidated. A clearer understanding of the association of AF with dementia and cognitive impairment is imperative. Future studies should focus on the predictors of cognitive impairment among those with AF and aim to understand the potential mechanisms underlying these associations. This would inform strategies for the management of AF aiming to prevent continued cognitive impairment.

Subclinical atrial fibrillation (SCAF) describes asymptomatic episodes of atrial fibrillation (AF) that are detected by cardiac implantable electronic devices (CIED). The increased utilization of CIEDs renders our understanding of SCAF important to clinical practice. Furthermore, 20% of AF present initially as a stroke event and prolonged cardiac monitoring of stroke patients is likely to uncover a significant prevalence of SCAF. New evidence has shown that implanting cardiac monitors into patients with no history of atrial fibrillation but with risk factors for stroke will yield an incidence of SCAF approaching 30-40% at around three years. Atrial high rate episodes lasting longer than five minutes are likely to represent SCAF. SCAF has been associated with an increased risk of stroke that is particularly significant when episodes of SCAF are greater than 23 h in duration. Longer episodes of SCAF are incrementally more likely to progress to episodes of SCAF >23 h as time progresses. While only around 30-40% of SCAF events are temporally related to stroke events, the presence of SCAF likely represents an important risk marker for stroke. Ongoing trials of anticoagulation in patients with SCAF durations less than 24 h will inform clinical practice and are highly anticipated. Further studies are needed to clarify the association between SCAF and clinical outcomes as well as the factors that modify this association.