# Demographic and cardiovascular risk factors associated with blood flow characteristics of the left atrium and left atrial appendage

## TL;DR

The study finds that age, race, and other factors are linked to blood flow changes in the left atrium, which could help predict stroke risk.

## Contribution

The study identifies demographic and cardiovascular risk factors associated with left atrial hemodynamics using 4D-flow MRI in a diverse population.

## Key findings

- Higher age and atrial fibrillation are linked to reduced peak velocity and increased blood stasis in the left atrium.
- Diabetes and higher BMI are associated with altered hemodynamics in the left atrium and left atrial appendage.
- Race and sex differences were observed in left atrial appendage blood flow characteristics.

## Abstract

Impaired left atrium (LA) and left atrial appendage (LAA) hemodynamics are risk factors (RF) for atrial thrombus formation and stroke. They can be assessed in vivo using 4D-flow-MRI; however, most studies involve clinical patient samples. We aimed to investigate demographic and cardiovascular (CV)-RF associations with LA and LAA hemodynamics in an observational study sample.

Participants from the multi-ethnic study of atherosclerosis from our institution were approached to undergo cardiac MRI, including 4D-flow-MRI. LA and LAA volume, blood stasis (%voxel with velocity < 0.1 m/s), and peak velocity (PV, top 5% of voxels) were calculated. CV-RF (demographics, history of atrial fibrillation (AF), body mass index (BMI), etc.) were available through study records and investigated in multivariable linear regression models.

One hundred fifty-eight participants were included (age: 72.8 ± 7.3 years, 53% female). Higher age and AF were associated with lower PVLA (βage: −0.16, p < 0.01; βAF: −2.81, p < 0.05) and higher LA stasis (βage: 0.64, p < 0.001; βAF: 5.60, p < 0.05). On the other hand, diabetes and left ventricular ejection fraction were associated with higher PVLA (βdiabetes: 3.29, p < 0.01; βLVEF: 0.11, p < 0.05), and diabetes was also associated with lower LA stasis (β: −6.12, p < 0.05). PVLAA was lower in Black participants (β: −2.64, p < 0.01) and AF (β: −4.33, p < 0.001). LAA stasis was lower in males (β: −5.36, p < 0.01), white participants (β: −3.69, p < 0.05), diabetes (β: −4.54, p < 0.01) and higher BMI (β: −0.42, p < 0.05) while higher LA volume (β: 0.12, p < 0.01) was associated with higher LAA stasis.

We identified RF associated with impaired LA and LAA hemodynamics in an observational study cohort.

Question
Are there associations of demographic and CV factors with impaired atrial hemodynamics from 4D-flow cardiac MRI?

Findings
4D-flow MRI identified, amongst others, higher age, race, history of AF, and BMI in a sub-cohort of the Multi-Ethnic Study of Atherosclerosis.

Clinical relevance
Understanding risk factor associations with atrial hemodynamics could aid in identifying subclinical atrial thrombus formation risks, potentially allowing for earlier preventive strategies against diseases such as stroke in diverse populations.