Mechanical valve thrombosis: a tailored approach for a multiplex disease

Over the years, progress in the design and structure of mechanical prostheses has led to a considerable improvement in their hemodynamic features and durability, such that they are now preferable to bioprostheses in most cases (1,2). However, the use of mechanical prostheses remains burdened with the risk of complications, amongst which thrombosis is the most dreaded (1). Valve thrombosis is still associated with a high mortality, even if emergency medical or surgical treatment is promptly established (3). The reported mortality rate of redo surgery is dependent upon the patient’s status at presentation, and ranges from 8 to 20% for urgent cases up to 37 to 54% for critically ill patients (1,4,5). With the advent of new-generation prosthetic valves and improvements in surgical techniques, the perioperative mortality rate and longterm results have been improved (6,7). Because of the high surgical risk associated with valve replacement, during the 1980s thrombolysis was proposed as an alternative to surgery (4,8,9). Although the initial results for thrombolysis were encouraging, studies conducted in larger series of patients showed a significant risk of neurological complications and recurrent thrombosis, and consequently surgery remained the treatment of choice (8,9). Numerous studies have been carried out to identify the risk factors for prosthetic thrombosis (1,3), and the most frequently reported is inadequate or discontinued anticoagulant therapy (3). Other risk factors include previous endocarditis and the prosthetic valve model used, and while many authors have reported a major incidence of thrombosis in tilting-disc valves (2), few data exist regarding the mechanisms of this obstruction (10). Obstruction is most often thought to result from valve thrombosis, but the role of chronic pannus formation in causing obstruction is less well established (1,3) and the relationship between thrombus and pannus formation has not been fully elucidated. In this study, we reviewed the outcome of a series of consecutive patients suffering from mechanical valve thrombosis who had been treated either with surgery or thrombolysis. This investigation was carried out to better define the indications for surgery or thrombolysis in the treatment of prosthetic valve thrombosis