INTERFERENCE OF MITRAL-VALVE-STENOSIS WITH LEFT-VENTRICULAR DIASTOLE AND LEFT ATRIAL APPENDAGE FLOW

Atrial fibrillation (AF) has been reported as an independent risk fact or of systemic thromboembolism. Almost half of the left atrial thrombi are located in the left atrial appendage (LAA). LAA function, reflect ed by LAA flow, thus has an influence on the potential of distal embol ic complications. To identify factors other than atrial contraction th at influence LAA flow during AF, transthoracic and transesophageal ech ocardiographic studies were performed on 130 patients. Seventy patient s with nonrheumatic AF were divided into two groups with higher peak L AA outflow velocity (group 1) and lower peak LAA outflow velocity (gro up 2) at the ventricular systolic phase. Sixty patients with rheumatic AF were classified as group 3. Group 1 had a higher peak LAA outflow velocity than group 2 at both the ventricular systolic and diastolic p hases. Group 2 had a higher peak LAA outflow at the ventricular diasto lic phase than group 3 (18.9 +/- 8.0 vs. 11.8 +/- 7.5 cm/s, p < 0.001) , whereas there was no significant difference in the peak LAA outflow at the ventricular systolic phase between the two groups (9.6 +/- 4.0 vs. 10.8 +/- 6.8 cm/s, p = NS). Group 3 was subdivided according to mi tral valve area. Patients with severe mitral stenosis (mitral valve ar ea <1 cm(2)) had a significantly lower diastolic augmentation of LAA o utflow velocity (difference of LAA outflow velocity between ventricle systole and diastole) than patients with mild to moderate stenosis (0. 5 +/- 3.2 vs. 2.6 +/- 4.9 cm/s, p < 0.05). In conclusion, patients wit h rheumatic AF, especially those with severe mitral stenosis, have a l ower diastolic augmentation of LAA outflow velocity. The lower diastol ic augmentation of the LAA outflow velocity at the ventricular diastol ic phase might result from interference with the suction effect of the left ventricular diastole by the stenotic mitral valve.