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Researchers found a potentially treatable risk factor for dementia in atrial myopathy, according to an exploratory analysis of the Atherosclerosis Risk in Communities (ARIC) study.

Significant associations were revealed between ARIC participants in their 70s and 80s and several echocardiographic measures of left atrial (LA) function and dementia. Over a median follow-up of 6 years, dementia rates were particularly high for people in the lowest quintiles of:

• LA reservoir strain: 4.80 per 100 person-years (HR 1.98 vs highest quintile, 95% CI 1.42-2.75)

• LA conduit strain: 3.94 per 100 person-years (HR 1.50, 95% CI 1.09-2.06)

• LA contractile strain: 3.29 per 100 person-years (HR 1.57, 95% CI 1.16-2.14)

• LA emptying fraction: 4.20 per 100 person-years (HR 1.87, 95% CI 1.31-2.65)

• LA active emptying fraction: 3.27 per 100 person-years (HR 1.43, 95% CI 1.04-1.96)

Atrial myopathy is a precursor to atrial fibrillation (Afib). However, the study findings were independent of Afib, which mediated less than 2% of the association between each LA function measure and incident dementia, reported Wendy Wang, MD, MPH, of the University of Minnesota in Minneapolis, and colleagues.

As they noted in their study in , brain MRI showed the greater prevalence of brain infarcts in people with dementia versus no dementia among the cohort with reduced LA reservoir volumes.

"However, given the exploratory nature of this study, future studies should aim to confirm the observations, clarify mechanisms (e.g., 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 (e.g., anticoagulation) to prevent dementia," Wang's group urged.

Atrial fibrosis ablation was another possible intervention cited by vascular neurologist Shyam Prabhakaran, MD, MS, of the University of Chicago, and preventive cardiologist Philip Greenland, MD, of Northwestern University in Chicago, writing in an .

"Unlike Alzheimer disease, a degenerative condition without proven cure or treatment, vascular dementia is the second most common etiology and opens up opportunities for dementia prevention through treatment of known risk factors such as hypertension and Afib," the editorialists said.

The ARIC analysis identified 4,096 people without prevalent Afib and stroke at visit 5 (2011-2013) who had echocardiograms available. Mean age was 75 years, 60% were women, and 22% were Black.

The 531 people who had incident dementia over follow-up tended to be older people and more likely Black, with a greater prevalence of cardiovascular disease and risk factors.

LA passive emptying fraction was not significantly associated with dementia, nor were LA maximal volume index and minimal volume index.

Besides the observational nature of the study, another major limitation was the varying methods in which dementia was diagnosed in the study, the researchers said.

Moreover, an ambulatory ECG monitoring device was worn by just 44% of study participants to screen for Afib. As such, some cases may have been missed, Wang and colleagues acknowledged.

Cardiac MRI may be helpful in better identifying how atrial myopathy contributes to dementia, as well as stroke and Afib, commented Prabhakaran and Greenland. "As the authors acknowledge, additional research in this area is needed but this report offers the hope for new ways to identify risk factors for dementia that are potentially treatable before dementia occurs."

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