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Regional left atrial stasis during atrial fibrillation and flutter: determinants and relation to stroke
B K Shively1, E A Gelgand, M H Crawford
1Albuquerque Veterans Affairs Medical Center, New Mexico 87108, USA.
Insights
Left atrial stasis, particularly in the posterior region, significantly increases stroke risk during atrial arrhythmia. Transesophageal echocardiography can identify patients with low blood flow velocity at high risk.
Area of Science:
- Cardiology
- Echocardiography
- Vascular Medicine
Background:
- Stroke during atrial arrhythmia is linked to left atrial stasis, but the precise location and risk factors remain debated.
- While appendage stasis is associated with thrombus, strokes often occur without it, suggesting other atrial regions are involved.
Purpose of the Study:
- To pinpoint left atrial stasis locations during arrhythmias.
- To quantify stasis levels correlating with stroke risk.
- To identify clinical and echocardiographic predictors of left atrial stasis.
Main Methods:
- Transesophageal pulsed wave Doppler echocardiography assessed blood flow velocity in the left atrium and appendage in 89 patients with atrial fibrillation/flutter.
- Regional velocities were correlated with probable embolic stroke frequency and clinical/echocardiographic data.
Main Results:
- The posterior left atrium and appendage showed the lowest blood flow velocities.
- Stroke risk rose sharply with velocities below 15 cm/s (87% sensitivity, 40% specificity).
- Predictors of stasis included low left atrial ejection fraction, significant mitral regurgitation, fibrillation, left ventricular dilation, and small mitral valve area.
Conclusions:
- Posterior left atrial stasis is as critical as appendage stasis for stroke risk, with risk escalating at lower flow velocities in both areas.
- Patients with left ventricular dilation and low atrial ejection fraction, alongside left atrial dilation, are prone to severe stasis.
- Transesophageal echocardiography measurement of atrial velocity aids in identifying patients at high risk for stroke during atrial arrhythmia.
Objectives:
This study sought to 1) determine the location of left atrial stasis during atrial arrhythmia; 2) define the degree of stasis associated with significant risk of stroke; and 3) identify clinical or transthoracic echocardiographic data useful for predicting left atrial stasis.
Background:
Prior studies suggest that stroke during atrial arrhythmia is related to stasis in either the body of the left atrium or the appendage. Recent data indicate that appendage stasis is associated with appendage thrombus formation, but stroke during atrial arrhythmia occurs frequently in the absence of appendage stasis.
Methods:
Blood flow velocity was measured in multiple sites in the body of the left atrium and in the appendage by transesophageal pulsed wave Doppler echocardiography in 89 patients with atrial fibrillation or flutter. Regional velocities were related to the frequency of probable embolic stroke and to clinical and transthoracic echocardiographic variables.
Results:
The lowest velocity region was either the posterior left atrium or the appendage. Stroke frequency increased progressively and steeply with velocity < 15 cm/s in either region; this cutoff value had an 87% sensitivity and 40% specificity for stroke. Factors related to stasis were low left atrial ejection fraction, mitral regurgitation < 3+, fibrillation (vs. type I flutter), left ventricular dilation and mitral valve area < 2.0 cm2.
Conclusions:
Posterior left atrial stasis appears to be as important as appendage stasis for the risk of stroke, which increases steeply with lower blood flow velocity in either region. Patients likely to have severe stasis during atrial arrhythmia are those with left ventricular dilation and low atrial ejection fraction accompanying left atrial dilation. Direct measurement of atrial velocity by transesophageal echocardiography appears to be useful for the identification of patients at risk for stroke during atrial arrhythmia.