Reports of frequent fracturing of Sprint Fidelis leads on Medtronic implantable defibrillators had been piling up for months, but the company only chose to withdraw the defective leads earlier this week. According to new reports, by January 2007, the Food & Drug Administration (FDA) knew of hundreds of cases where the Sprint Fidelis lead fractured and caused serious injuries in people with Medtronic implantable defibrillators, yet neither the agency nor Medtronic took any action at that time.
Earlier this week, Medtronic suspended sales and recalled the Sprint Fidelis lead used in its implantable defibrillators after an analysis of the company's data showed that the lead had a continuing fracture problem. According to Medtronic's own estimate, approximately 2.3%, or 4,000 to 5,000 people with a Sprint Fidelis lead will experience fracture within 30 months of having a defibrillator implanted.
The Sprint Fidelis lead is a wire that runs through a blood vessel and attaches a defibrillator to the heart. Lead wires are usually one of the more fragile components of a defibrillator, but that seems to have been especially true in the case of the Sprint Fidelis lead. Since it was introduced to the market in 2004, the FDA had received 599 reports of lead fractures as of January 2007. And it seems as though the fracture problems became worse over time. In the first two months of 2006, there were 27 reports of the Sprint Fidelis lead fracturing. But in the first two months of 2007, there were 152 reports. And since January 10, 2007, the FDA has received a staggering 1,030 reports of fractures. So far, 5 patient deaths have been linked to fractures of the Sprint Fidelis lead.
And lead fractures involve far more than a damaged wire. When a defibrillator lead fails, it can cause the device to emit unnecessary and massive painful shocks to the heart. One researcher has described this event as akin to being "kicked in the chest" by a horse. Or even worse, the fractured lead can cause the defibrillator to fail to emit a life saving shock when needed. Even when a lead fracture is detected before either of those things happen, patients must undergo a dangerous and life-threatening surgery to have the wire replaced.
Despite having so many reports of Sprint Fidelis lead fractures, the FDA did not start monitoring the component until February, after the Minneapolis Heart Institute published a study of lead failures in the Sprint Fidelis models compared to the Sprint Quattro models, another type of Medtronic lead. The researchers in Minneapolis found that the thinner Sprint Fidelis lead had a higher chance of fracturing than the Sprint Quattro. As a result of those findings, the Minneapolis Heart Institute quit using the Sprint Fidelis lead, and the study authors informed the FDA that the defective Sprint Fidelis lead was "significantly less reliable" than its predecessor. While Medtronic did write a letter to doctors in March 2007 warning them of the lead's possible problems, the company maintained that the fractures were partly the result of the leads not being properly implanted. For its part the FDA did nothing further in response to the Minnesota Heart Institute's report.
Even now, the FDA insists that there was no early evidence that the Sprint Fidelis lead was more apt to break than other defibrillator lead wires. But Medtronic's decision to pull the Sprint Fidelis lead from the market has prompted the FDA to re-examine other models of similarly sized defibrillator leads.