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Catheter Ablation in Combination With Left Atrial Appendage Closure for Atrial Fibrillation
Published on: February 26, 2013
Slow blood-flow in the left atrial appendage is associated with stroke in atrial fibrillation patients
Nikhil Paliwal1, Hwan-Cheol Park2, Yuncong Mao3
1Alliance for Cardiovascular Diagnostic and Treatment Innovation, Johns Hopkins University, Baltimore, MD, USA.
Insights
Slow blood flow in the left atrial appendage (LAA) is linked to stroke in atrial fibrillation (AF) patients. Hemodynamic analysis can help identify stroke risk in AF patients.
Area of Science:
- Cardiovascular Imaging
- Biomedical Engineering
- Clinical Hemodynamics
Background:
- Atrial fibrillation (AF) patients face a high stroke risk, with clots often originating in the left atrial appendage (LAA).
- Understanding blood flow dynamics in the LA and LAA is crucial for predicting stroke risk in AF patients.
- This study investigates the association between blood flow parameters and stroke events in AF patients.
Purpose of the Study:
- To determine if slow blood flow in the left atrium (LA) or LAA is associated with stroke in AF patients.
- To compare hemodynamic and geometric parameters between AF patients with and without a history of stroke.
- To explore the potential of patient-specific blood flow analysis for stroke risk stratification.
Main Methods:
- Retrospective analysis of cardiac CT images from paroxysmal AF patients, categorized into stroke and non-stroke groups.
- 3D LA and LAA geometry reconstruction and segmentation for hemodynamic modeling.
- Quantification of blood flow velocity, wall shear stress (WSS), oscillatory shear index (OSI), and endothelial cell activation potential (ECAP) in the LA and LAA.
Main Results:
- The stroke group exhibited significantly lower blood velocity and WSS, and higher ECAP in the LAA compared to the non-stroke group.
- Left inferior pulmonary vein area was significantly larger in the stroke group.
- No significant difference in LAA morphology was observed between the groups.
Conclusions:
- Slow and oscillatory blood flow in the LAA is associated with stroke in paroxysmal AF patients.
- Patient-specific hemodynamic analysis, particularly of LAA flow, can aid in identifying AF patients at high risk of stroke.
- These findings highlight the importance of LAA hemodynamics in thrombogenesis and stroke risk stratification.
Background:
Atrial fibrillation (AF) patients are at high risk of stroke with ∼90% clots originating from the left atrial appendage (LAA). Clinical understanding of blood-flow based parameters and their potential association with stroke for AF patients remains poorly understood. We hypothesize that slow blood-flow either in the LA or the LAA could lead to the formation of blood clots and is associated with stroke for AF patients.
Methods:
We retrospectively collected cardiac CT images of paroxysmal AF patients and dichotomized them based on clinical event of previous embolic event into stroke and non-stroke groups. After image segmentation to obtain 3D LA geometry, patient-specific blood-flow analysis was performed to model LA hemodynamics. In terms of geometry, we calculated area of the pulmonary veins (PVs), mitral valve, LA and LAA, orifice area of LAA and volumes of LA and LAA and classified LAA morphologies. For hemodynamic assessment, we quantified blood flow velocity, wall shear stress (WSS, blood-friction on LA wall), oscillatory shear index (OSI, directional change of WSS) and endothelial cell activation potential (ECAP, ratio of OSI and WSS quantifying slow and oscillatory flow) in the LA as well as the LAA. Statistical analysis was performed to compare the parameters between the groups.
Results:
Twenty-seven patients were included in the stroke and 28 in the non-stroke group. Examining geometrical parameters, area of left inferior PV was found to be significantly higher in the stroke group as compared to non-stroke group (p = 0.026). In terms of hemodynamics, stroke group had significantly lower blood velocity (p = 0.027), WSS (p = 0.018) and higher ECAP (p = 0.032) in the LAA as compared to non-stroke group. However, LAA morphologic type did not differ between the two groups. This suggests that stroke patients had significantly slow and oscillatory circulating blood-flow in the LAA, which might expose it to potential thrombogenesis.
Conclusion:
Slow flow in the LAA alone was associated with stroke in this paroxysmal AF cohort. Patient-specific blood-flow analysis can potentially identify such hemodynamic conditions, aiding in clinical stroke risk stratification of AF patients.
