Significance of “Strands” on Mitral Mechanical Prostheses During Late Follow‐Up After Surgery

: The presence of "strands" on mitral mechanical prostheses (MMP) has been described, although their significance has yet to be established. The aim of this study was to determine the incidence and clinical implications of "strands" on MMP in late follow-up by a retrospective analysis of 320 consecutive patients who had undergone a transesophageal echocardiographic (TEE) examination under standardized conditions 7 +/- 6 years after mitral surgery. Twenty patients (6.25%) with "strands," defined as highly mobile linear echogenic densities, were identified. This group was compared with a control group of 38 patients, matched for age, sex, and interval between surgery and TEE study, selected at random from this population. Patients with MMP dysfunction were excluded. Type of prosthesis, echographic characteristics (left atrial diameter, spontaneous echo contrast, ejection fraction), and anticoagulant status were not found to bear any relationship to the presence of strands. However, the prevalence of previous embolic events was significantly higher in the "strand" group (10/20 [50%]) than in the control group (7/38 [18.4%]) (P < 0.05). The "strand" group also contained more patients with a prior history of mitral prosthesis thrombosis (7/20 [35%] vs 1/30 [2.6%]; P < 0.05). However, long-term follow-up (1-4 years) was uneventful. These results suggest that: (1) in late follow-up, strands are rare in patients with MMP (6%); and (2) strands were related to previous thromboembolic episodes. (ECHOCARDIOGRAPHY, Volume 13, May 1996)