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Effect of inotropic stimulation on left atrial appendage function in atrial myopathy of chronic atrial fibrillation
M Kamalesh1, T B Copeland, S Sawada
1VA Medical Center, 1900 E. Main St., Danville, IL 61832, USA.
Insights
In patients with atrial fibrillation (AF), dobutamine modestly improved left atrial appendage (LAA) function, but LAA function remained impaired compared to normal sinus rhythm. Spontaneous echo contrast showed minimal improvement.
Area of Science:
- Cardiology
- Echocardiography
- Electrophysiology
Background:
- Atrial fibrillation (AF) causes left atrial (LA) and left atrial appendage (LAA) remodeling, leading to atrial myopathy.
- Reduced LA and LAA function in chronic AF contributes to thrombus formation and spontaneous echo contrast (SEC).
- The impact of inotropic stimulation on LAA function in patients with chronic AF is not well understood.
Purpose of the Study:
- To investigate the effect of inotropic stimulation (dobutamine) on LAA function and SEC in patients with chronic AF.
- To compare LAA function in patients with AF versus normal sinus rhythm (NSR) under dobutamine stress.
Main Methods:
- Transesophageal echocardiography was used to measure LAA emptying velocity (LAAEV) and maximal LAA area.
- Measurements were taken at baseline and after dobutamine administration in 14 subjects in NSR and 6 subjects in AF.
- SEC in the LA was assessed before and after dobutamine.
Main Results:
- LAAEV significantly increased in both AF and NSR groups following dobutamine.
- However, peak LAAEV in the AF group remained significantly lower than baseline LAAEV in the NSR group.
- Maximal LAA area decreased with dobutamine, but remained larger in the AF group compared to baseline in the NSR group.
- SEC improved in only two of five patients despite increased LAAEV.
Conclusions:
- The LAA exhibits a modest functional response to inotropic stimulation during AF.
- LAA function in patients with AF remains significantly impaired even with dobutamine, compared to baseline function in NSR patients.
- Inotropic stimulation has limited efficacy in improving SEC in the LA during AF.
Abstract:
Atrial fibrillation (AF) leads to remodeling of the left atrium (LA) and left atrial appendage (LAA), resulting in atrial myopathy. Reduced LA and LAA function in chronic AF leads to thrombus formation and spontaneous echo contrast (SEC). The effect of inotropic stimulation on LAA function in patients with chronic AF is unknown. LAA emptying velocity (LAAEV) and maximal LAA area at baseline and after dobutamine were measured by transesophageal echocardiography in 14 subjects in normal sinus rhythm (NSR) and 6 subjects in AF. SEC in the LA was assessed before and after dobutamine. LAAEV increased significantly in both groups. However, the LAAEV at peak dobutamine in patients with AF remained significantly lower than the baseline LAAEV in patients who were in NSR (P = 0.009). Maximal LAA area decreased significantly with dobutamine in both groups, but LAA area at peak dose of dobutamine in patients with AF remained greater than baseline area in those in NSR (P = 0.01). Despite the increase in LAAEV, SEC improved in only two of five patients. We conclude that during AF, the LAA responds to inotropic stimulation with only a modest improvement in function.
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