The Silzone effect: how to reconcile contradictory reports?

OBJECTIVE To attempt to reconcile reports containing contradictory findings with the St. Jude Medical Silzone heart valve. METHODS Major leak and thromboembolism data were extracted from available Silzone valve studies. Linearized rates were used to summarize and compare the events rates among the studies. RESULTS The Artificial Valve Endocarditis Reduction Trial (AVERT) study reported significant higher rate of major leak and the Cardiff Embolic Risk Factor Study (CERFS) reported significant higher rate of thromboembolism with Silzone compared to non-Silzone valves. But, current updates of these studies show a diminution of these differences. Three other comparative studies reported no difference between Silzone and non-Silzone valves, and three single arm studies reported acceptable results with Silzone valves. CONCLUSION The contradictory findings could be partly due to clinical and technical reasons. No new events have been reported since the original AVERT (major leak) and CERFS (mitral thromboembolism) publications.