Left atrial appendage blood flow analysis using four-dimensional flow magnetic resonance imaging

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.