Medtronic released the updated survival rates on Tuesday for its Sprint Fidelis lead models 6949, 6948, 6931, 6930, using its CareLink network and System Longevity Study (SLS) data.
In October 2007, the company voluntarily suspended worldwide distribution of its Sprint Fidelis family of defibrillation leads because of the potential for lead fractures. Medtronic also recommended against new implants of the leads of Sprint Fidelis models: 6930, 6931, 6948 and 6949. Since that time, the company has endured considerable scrutiny and mounting lawsuits over the faulty leads.
According to the Minneapolis-based company, the data show 42-month survival rate of 96.2 percent for CareLink network and 93.7 percent for SLS data. The statistics compare to one-year survival rates of 99.8 percent for CareLink network and 98.7 percent for SLS data.
The company noted that the estimated survival probability of the SLS survival curve may change over time due to the limited accuracy associated with small sample sizes. Smaller study populations can artificially skew results, as small data movements in smaller samples can bring about disproportionately large percentage changes, according to Medtronic. For example, a single event in a population with an effective sample size of approximately 50 leads can change the estimated survival probability by 2 percent.
“As the implanted population ages and the sample size increases for each time interval, the accuracy of the estimated survival probability will increase as shown by tighter confidence intervals,” they wrote.
In a letter to patients, the company informed them that the “chance that there will be a problem with your Sprint Fidelis lead remains small.”