The influence of left ventricular diameter on left atrial appendage size and thrombus formation in patients with dilated cardiomyopathy

Objectives: Patients with dilated cardiomyopathy are considered a high risk group for left ventricular (LV) thrombus formation. However, the left atrial appendage (LAA) might be an additional site for thrombus formation in this patient group. We evaluated the association between LV size and left atrium/LAA size and determined the incidence of spontaneous echo contrast (SEC)/thrombus in the LV, left atrium, and LAA in patients with and without enlarged LV dimensions. Study design: In a prospective design, we examined 45 patients with transthoracic and transesophageal echocardiography. Nineteen patients had an enlarged LV dimension (group 1: LV end-diastolic diameter >= 58 mm), and 26 patients had a normal LV size (group 2). Nonvalvular atrial fibrillation (AF) was present in 13 patients (68.4%) in group 1 and in 14 patients (53.9%) in group 2. Echocardiographic parameters included LV dimension and ejection fraction, left atrial diameter, LAA maximal area, and detection of SEC/thrombus in the LV, left atrium, and LAA. Results: The two groups were similar with regard to demographic and clinical features. Patients in group 1 had a significantly increased LV end-diastolic diameter (63.5 +/- 3.8 mm vs. 50.9 +/- 0.9 mm; p<0.001) and decreased ejection fraction (45.3 +/- 11.7% vs. 56.0 +/- 10.2%; p=0.002). Left atrial diameter did not differ significantly, but maximal LAA area was significantly greater in group 1 (4.9 +/- 2.3 cm(2) vs. 3.3 +/- 0.8 cm(2); p=0.002). Among the frequencies of SEC and thrombus in the LV, left atrium, and LAA, only the frequency of thrombus in the LAA was significantly higher in group 1 (36.8% vs. 7.7%; p=0.05). Compared to patients with a normal LV size and AF, the coexistence of AF with dilated LV was significantly associated with a greater LV end-diastolic diameter (p<0.001) and LAA maximal area (p=0.02). Conclusion: Patients with a dilated LV have a larger LAA and seem to be at a higher risk for LAA thrombus formation. Key words: Atrial appendage/ultrasonography; atrial fibrillation/complications; cardiomyopathy, dilated/complications; echocardiography, transesophageal; thrombosis/diagnosis.