Original article: cardiovascularParavalvular leak and other events in silzone-coated mechanical heart valves: a report from AVERT
Section snippets
Study protocol
Details of the hypothesis, study design, and sample size determination have been presented previously [4]. Briefly, the AVERT trial was developed to determine whether Silzone coating of prosthetic valve sewing rings reduces the risk of PVE. The study assumed that for uncoated prostheses, the rate of early PVE (less than 60 days) is 1%, and the subsequent risk of late PVE is 0.5% per year. To detect a 50% reduction in risk of PVE (80% power, p < 0.05), the trial would have to randomize
Patient characteristics
Patients were on average 61 years old, and 41.1% were women. Five percent of patients had active, treated, or suspected endocarditis at the time of operation. Most study patients had New York Heart Association functional class II (40.9%) or III (42.4%) at the time of implant; 8.7% were class I, and 8% were class IV. History of myocardial infarction was reported in 8.9%, history of diabetes in 14.3%, and congestive heart failure within 2 weeks of operation in 22.6%. Coronary artery disease,
Comment
These results confirm and extend the interim analysis of AVERT that led to discontinuation of enrollment and voluntary withdrawal of the Silzone valve because of an unacceptably high risk of explant due to major paravalvular leak. The increased risk of major PV leak was observed for patients with aortic valve replacement, mitral valve replacement, and double valve replacement.
The mechanism responsible for development of PV leak in patients receiving the Silzone prosthesis is unclear. In
Addendum
As of December 5, 2001 follow-up on Silzone patients in the study had increased to 686 valve-years and included 277 patients reporting 2-year follow-up. No additional instances of valve repair or explant due to PV leak have been reported.
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