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 clin ical im plications of ''strands'' on MMP in Late follow-up by a retrospective analysis of 320 consecutive patients who had undergone a transesophage al echocardiographic (TEE) examination under standardized conditions 7 +/- 6 years after mitral surgery. Twenty patients (6.25%) with ''stra nds,'' defined as highly mobile Linear echogenic densities, were ident ified. This group was compared with a control group of 38 patients, ma tched for age, sex, and interval between surgery and TEE study, select ed at random from this population. Patients with MMP dysfunction, were excluded. Type of prosthesis, echographic characteristics (left atria l diameter, spontaneous echo contrast, ejection fraction), and anticoa gulant status were not found to bear any relationship to the presence of strands. However, the prevalence of previous embolic events was sig nificantly higher in the ''strand'' group (10/20 [50%]) than in the co ntrol group (7/38 [18.4%]) (P < 0.05). The ''strand'' group also conta ined more patients with a prior history of mitral prosthesis thrombosi s (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 fo llow-up, strands are rare in patients with MMP (6%); and (2) strands w ere related to previous thromboembolic episodes.