It seems there is some controversy brewing about the true failure rate for Medtronic Inc.’s recalled Sprint Fidelis defibrillator lead. According to The Wall Street Journal, Medtronic says its own research shows the Sprint Fidelis leads survive for three years at least 95.4% of the time, for a failure rate of 4.6%. But data from some leading hospitals indicates the true rate could be much higher.

Medtronic Inc.’s Sprint Fidelis lead was removed from the market in October 2007, following reports of 5 deaths due to lead fractures. Before the recall, Sprint Fidelis leads had been implanted with 90% of Medtronic’s defibrillators.

In March 2009, Medtronic reported that the faulty wires were a “possible or likely contributing factor” in as many as 13 deaths. Four of the deaths occurred when doctors tried to remove defective Sprint Fidelis leads from patients. Now, The Wall Street Journal is reporting that according to the Food & Drug Administration (FDA) database, 12 additional deaths allegedly linked to the Sprint Fidelis have been reported to the agency since last March

According to The Wall Street Journal, a report from the University of Rochester published in the January issue of the American Journal of Cardiology said the three-year survival rate of 426 Medtronic leads inserted in patients there was 90.8%, meaning 9.2% failed. A report from the Mayo Clinic published last February in the journal HeartRhythm said the estimated rate of failure among 848 leads implanted there after three years of use was 12.1%.

In November, a separate Mayo Clinic study showed the failure rate for Sprint Fidelis leads after two years was 20.4% in patients younger than 50, while the rate in older patients was only 3.5%. Another HeartRhythm study published in October 2008 by the University of Ottawa found the risk of a Sprint Fidelis fracture “increased significantly with time.”