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Updated: Jan 6, 2026
In vitro Assessment of Aortic Regurgitation Using Four-Dimensional Flow Magnetic Resonance Imaging
Published on: February 25, 2022
Left atrial appendage blood flow analysis using four-dimensional flow magnetic resonance imaging
Akihito Ohkawa1, Tomohiro Nakajima2, Shingo Tsushima2
1Department of Cardiovascular Surgery, Sapporo Medical University, Minami 1 Jo Nishi 17 Chome 291, Chuou-ku, Sapporo, Hokkaido, Japan. akihito.ookawa7719@gmail.com.
Insights
Blood flow stagnation in the left atrial appendage (LAA) top segment occurs in high-risk patients even with sinus rhythm. This finding may improve stroke prevention strategies using LAA closure.
Area of Science:
- Cardiology
- Medical Imaging
Background:
- Blood flow stagnation in the left atrial appendage (LAA) is a primary cause of thrombus formation in atrial fibrillation.
- Stagnant LAA flow is also suspected in patients with sinus rhythm and elevated stroke risk.
Purpose of the Study:
- To evaluate LAA blood flow using 4D flow MRI in patients stratified by CHA2DS2-VASc scores.
- To identify correlations between stroke risk factors and LAA hemodynamics.
Main Methods:
- Ninety-eight participants (70 patients, 28 controls) with sinus rhythm underwent non-contrast 4D flow MRI.
- Participants were categorized into low (CHA2DS2-VASc 0-2) and high (CHA2DS2-VASc 3-9) risk groups.
- LAA blood flow volume in basal, middle, and top segments was analyzed and compared.
Main Results:
- Significantly reduced blood flow volume was observed in the LAA top segment of the high-risk group compared to the low-risk group (p=0.006).
- No significant differences in blood flow volume were found in the basal and middle LAA segments between groups.
- Larger LAA volumes correlated with reduced top-segment flow, but not significantly with intra-LAA flow.
Conclusions:
- High CHA2DS2-VASc scores are associated with LAA top segment blood flow stagnation, even in sinus rhythm.
- Developing blood flow-based criteria could enhance LAA closure applications for stroke prevention.
Objective:
Thrombus formation in atrial fibrillation is caused by blood flow stagnation within the left atrial appendage (LAA). It is believed that blood flow tends to stagnate within the LAA even in patients with sinus rhythm and high risk of stroke. This study evaluated blood flow within the LAA using four-dimensional flow magnetic resonance imaging among patients stratified by the congestive heart failure, hypertension, age, diabetes mellitus, prior stroke, vascular disease, age, sex category (CHA2DS2-VASc) score.
Methods:
Ninety-eight participants with sinus rhythm (70 patients, 28 controls) underwent non-contrast four-dimensional flow magnetic resonance imaging. Participants were divided into low- and high-risk groups (CHA2DS2-VASc scores 0-2 and 3-9, respectively. Blood flow parameters, including the blood flow volume in the basal, middle, and top segments of the LAA, were analyzed and compared between groups.
Results:
The blood flow volume was significantly reduced in the top segment of the LAA in the high-risk group (low-risk: 3.13 ± 1.07 mL/cm2 vs. high-risk: 2.54 ± 0.96 mL/cm2, p = 0.006). However, the blood flow volume in the basal and middle segments did not differ significantly between the two groups (basal segment, p = 0.14; middle segment, p = 0.44). In addition, larger LAA volumes (EDV, ESV, and mean volume) were associated with reduced top-segment flow, but correlations with intra-LAA flow were not statistically significant.
Conclusions:
In patients with high CHA2DS2-VASc scores, blood flow stagnation can occur in the LAA top segment even in the presence of sinus rhythm. Establishing blood flow-based criteria may enhance the potential applications of LAA closure to prevent stroke.
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