Incidência de trombo intracardíaco e de tromboembolismo nos três primeiros meses após o implante de bioprótese valvar

Abstract

Although bioprostheses are less thrombogenic than mechanical prostheses, several reports of thromboembolism related to their use exist, mainly in the first 3 months after their implantation 1-5. Three basic mechanisms for the formation of intracardiac thrombi after prosthetic implantation may be identified as follows: 1) the first involves a molecular interaction between blood components, plasma, and the artificial surface of the prostheses; 2) the second depends on the influence of transprosthetic blood flow and residual stenosis; and 3) the third refers to states of hypercoagulability, loss of atrial contraction, imperfections on the prosthetic surfaces, and incomplete endothelialization of the prosthetic ring 2. In addition, the glutaraldehyde used for valve preservation, even in low concentrations, is also deleterious to the endothelium 6. Although their independent role in thrombus formation has not been confirmed, dilation of the cardiac chambers and left ventricular dysfunction are associated with a greater incidence of thrombotic events 7. Another risk factor for thrombus formation is the spontaneous contrast 8 found in conditions of low blood-flow velocity. Some arrhythmias, particularly atrial fibrillation, have been associated with thrombus formation 9-11. With the appearance of transesophageal echocardiography, the diameters and function of the atrial appendage could be directly assessed 12 , and, regardless of the cardiac rhythm, the disappearance of or decrease in blood flow velocity in the exit of the left atrial appendage has been associated with the presence of spontaneous contrast and thrombus formation 13,14. The impact of bioprosthesis implantation on the formation of intracardiac thrombus and on embolic complications, especially in patients with sinus rhythm, has been studied little in a prospective form, especially in our country. Therefore, the incidence of thrombus in the first 3 months after bioprosthetic implantation needs to be known, as do the risk factors that may influence thrombus formation, to justify the prescription of oral anticoagulants in that population of patients, as recommended by the guidelines of the American Heart Association and American College of Cardiology 15. This study aimed at assessing the incidence of intracardiac thrombus and thromboembolism in the first 3 months after porcine bioprosthetic valve implantation and at identifying the clinical, laboratory, and echocardiographic risk factors for thrombus formation after bioprosthesis implantation. Methods This study comprised 184 patients, 107 (58.0%) women and 77 (42.0%) men, with ages ranging from 15 to 75 years (mean,