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SPONTANEOUS ECHO CONTRAST IN MITRAL STENOSIS: WHY AND HOW?

Background: Spontaneous echo contrast (SEC) is an echocardiographic finding particularly found in left atrium of patients with mitral stenosis and known as a risk factor for stroke. However, its pathophysiology is not fully understood. Material and Method: Forty-eight patients with mitral stenosis scheluded for percutaneous mitral valvuloplasty were included in the study. The severity of SEC was graded from 0 to 4 according to its density. Blood samples were taken from the aorta and left atrium during the procedure. Whole blood viscosity, plasma viscosity and peripheral blood smears were obtained and analysed separately from these sites. Results: Severe SEC (grade 3-4) was found in 23 patients (48%), remaining 25 patients (52%) had mild to moderate SEC (grade 0-1-2). The patients with atrial fibrillation (AF) and hypertension (HT) had more significantly severe SEC compared to other patients. A history of stroke, rouleaux formation at the peripheral smears, mitral valve area, transmitral diastolic gradient, left atrial mean wall velocities and total atrial conduction time were not different between two groups. Compared to patients with mild to moderate SEC, patients with severe SEC had increased age, body mass index (BMI), left atrial diameter, left atrial area and left atrial plasma viscosity (PV). However, ejection fraction, left atrial appendage (LAA) filling and emptying velocities, LAA lateral wall late systolic velocity, LAA fractional area change and pulmonary vein (PVe) systolic velocity were found to be significantly reduced in patients with severe SEC compared to mild to moderate SEC. On multiple linear regression analysis, AF, left atrium PV and left atrial diameter were the strongly correlated with SEC grade. Conclusion: In conclusion, we have shown that AF, HT, systolic dysfunction of LAA, increased left atrial dimensions, reduced ejection fraction, decreased PVe flow velocity and increased left atrial PV were related with the development of SEC in patients with mitral stenosis.