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Atrial myopathy may contribute to dementia risk

Reuters Health - 22/03/2022 - Impaired left atrial (LA) function may be a risk factor for dementia, according to an exploratory analysis of data from the Atherosclerosis Risk in Communities (ARIC) study.

The analysis found statistically significant associations between measures of lower LA function and an increased risk of subsequent dementia, report Dr. Wendy Wang of the University of Minnesota, in Minneapolis, and colleagues.

This analysis introduces "intriguing concepts" regarding how atrial myopathy, however defined, may contribute to dementia risk, say the authors of an editorial published with the study in JAMA.

The findings are based on 4,096 older ARIC participants (mean age, 75 years; 60% women; 225 Black) without prevalent atrial fibrillation (AF) or stroke who underwent two-dimensional echocardiography between 2011 and 2013 and were followed until the end of 2019.

Atrial myopathy was defined using a number of different measures of LA size (maximal and minimal volume index) and function (reservoir strain, conduit strain, contractile strain, emptying fraction, passive emptying fraction, and active emptying fraction).

During a median follow-up of six years, 531 participants developed dementia.

The incidence of dementia for the lowest quintiles of LA function measures (per 100 patient-years) was 4.80 for reservoir strain, 3.94 for conduit strain, 3.29 for contractile strain, 4.20 for emptying fraction, 3.67 for passive emptying fraction and 3.27 for active emptying fraction.

In the fully adjusted model, the lowest (vs. highest) quintile was significantly associated with dementia for several LA function measures; statistically significant hazard ratios ranged from 1.43 to 1.87 for reservoir strain, conduit strain, contractile strain, emptying fraction and active emptying fraction.

The two measures of LA volume index were not significantly associated with dementia incidence. "These findings were robust to sensitivity analyses that excluded participants with incident AF or stroke," the study team notes.

"To our knowledge, this is the first study to report an independent association between echocardiographic measures of LA function with dementia," Dr. Wang and colleagues write.

"However, given the exploratory nature of this study, future studies should aim to confirm the observations, clarify mechanisms (eg, brain infarcts), and to confirm possible cutoff values that can be used to define abnormal LA function so that at-risk patients can be enrolled into future clinical trials to test potential interventions (eg, anticoagulation) to prevent dementia," they add.

In a linked editorial, Dr. Shyam Prabhakaran of the University of Chicago and Dr. Philip Greenland of Northwestern University agree more research is needed.

This study, they add, "offers the hope for new ways to identify risk factors for dementia that are potentially treatable before dementia occurs," they write.

However, "given the exploratory nature of the study findings, prospective validation in other cohorts is clearly necessary. Future studies using cardiac MRI to evaluate the atrial myopathy more completely may identify precisely which aspects of the diseased atrium are most important for development of dementia as well as stroke and atrial fibrillation," the add.

SOURCE: https://bit.ly/354VQCE and https://bit.ly/3qqz53t JAMA, online March 22, 2022.

By Reuters Staff

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