Silzone Mechanical Valves: Is the Story on Silzone Over?

Dallas, TXJust because the St. Jude Silzone mechanical heart valves were voluntarily recalled, that does not mean that the story about the St. Jude Silzone valves is entirely over. During the Silzone valve recall, which was announced in January 2000, St. Jude recommended that not all patients undergo surgery to remove and replace the valves. Of approximately 36,000 St. Jude mechanical Silzone valves implanted worldwide, around 10,500 valves were implanted in patients in the US. Some are likely still implanted.

The St. Jude Silzone valves were reportedly fine, mechanically. The problem was not with how the valve worked but with the Silzone coating on portions of the valve. The Silzone was made with silver to reduce the risk of patients developing an infection; however, that silver reportedly leaked (a condition known as paravalvular leakage), which made the patient's heart less effective and could result in heart failure.

In addition to the risk of heart failure, a trial called the Artificial Valve Endocarditis Reduction Trial (AVERT) reportedly showed an increased risk of stroke, valve thrombosis and reversible ishaemic neurological deficits in patients who had the Silzone valves implanted. Although the risk was not considered statistically significant, the study further showed a 2.76 percent incidence of paravalvular leakage in patients who had the Silzone valve implanted, compared to 1.02 percent incidence of paravalvular leakage in patients without the Silzone valve.

Because of these factors, the AVERT trial was halted early, at the same time the Silzone recall was announced.

In 2003, a study, published in the journal Heart (9/03), was conducted to study patients with St. Jude Silzone valves and determine adverse effects of the valves. Although researchers found that patients with the Silzone mitral valves had no excess paravalvular leak, they did find a high rate of early postoperative embolism as compared with standard St. Jude valves, which had no Silzone component.

A lawsuit was filed against St. Jude in British Columbia regarding the Silzone mechanical heart valve. In 2009, a settlement was announced between the members of the class action and St. Jude Medical. The settlement involved payments to patients who received the Silzone implant and did not suffer an adverse event, and those who did suffer an adverse event.