OBJECTIVE: Facing the hypothesis of participation of mechanical stress as a cause of mitral bioprosthesis dysfunction, we decided to assess the relation of preservation of the texture of the mitral bioprosthesis leaflets with left ventricular function, in addition to the casual formation of thrombus in left atrium in patients with left ventricular dysfunction from the implant of mitral bioprosthesis. METHODS: Forty 40 patients with mitral bioprosthesis through multiplane transesophageal echocardiogram were studied and divided in two groups: with left ventricular dysfunction (FE=0.40±0.09) since the bioprosthesis implant (20 patients: age 47.75±11.10 years old and surgery time 5.3±2.6 years) and with normal left ventricular function (FE=0.73±0.06) since the implant (20 patients: age 49.75±13.59 years old and surgery time 5.7±3 years). The texture of bioprosthesis leaflets was analyzed through a transesophageal echocardiographic score (FACIMT Bioscore): 1) Fusion of leaflets (score 1 to 3); 2) Apposition of tissues (score 1 to 3); 3) Calcium in leaflets (score 1 to 5); 4) Integrity of leaflets (score 1 to 3); 5) Motility of leaflets (score 1 to 4) and 6) Thickness of leaflets (score 1 to 3). The presence of thrombi in left atrium was assessed through multiplane scanning of the left atrium and left atrial appendage in the transesophageal study. RESULTS: There was no significant difference in the texture of bioprosthesis mitral position between the groups, for the total score (8.7±2.4 vs. 7.9±2.1, p=0.259), and for each analyzed item. A greater incidence of thrombi in left atrium and left atrial appendage was detected in patients with ventricular dysfunction (65% vs. 20%, p=0.004). CONCLUSION: The left ventricular dysfunction was not a protecting factor of the texture of bioprosthesis leaflets in mitral position in the tardive post-surgery period. The patients with left ventricular dysfunction showed a more favorable environment for the formation of thrombi in left atrium.