Medtronic issued the recall of leads in October, amid mounting evidence that a small percentage of the leads were fracturing.
Those fractures caused some patients to receive unneccessary shocks from their defibrillators, while other patients did not receive a lifesaving shock when they had a slow heart rhythm. The lead failures may have contributed to five deaths.
At the time of the recall, Medtronic took great pains to underscore that the Fidelis leads had a 2.3 percent failure rate after 30 months of implantation. That compared to a 1 percent failure rate among the company's Quattro leads, which have been around longer and are wider in diameter.
On a conference call with analysts Monday, Medtronic's president of Cardiac Rhythm Disease Management, Pat Mackin, said the company erred on the side of caution by pulling the Fidelis lead.
"We made a very conservative call with this lead. There is no statistically significant difference between Fidelis and Quattro, but we figured it would become so over time, which is why we made the action we did," said Mackin.
"We have a rule of thumb, and that is if you see three of the same thing at one center, you'd better pay attention to it, because it's likely not due to chance," said Dr. Robert Hauser, a cardiologist at the Minneapolis Heart Institute.
Hauser's clinic stopped using Medtronic's Fidelis lead in January after tracking six incidences of injuries from it.
In March, Hauser and his colleagues submitted an article about the problems they saw to the journal Heart Rhythm. That same month, Medtronic issued a letter to patients and doctors advising them of concerns about the Fidelis lead.
Hauser says Medtronic was actually very cooperative in addressing his worries about the product. And he believes Medtronic's claim that the company had to collect more data before it made sense to pull the leads from distribution.
But Hauser takes a less generous view of how the Food and Drug Administration handled things.
"When Medtronic sent a letter to physicians stating they 'may' have a problem, from that point on, in my view, the ball was in the FDA's court," Hauser says. "In retrospect, what might've been done was for the FDA to say simply, 'Look, if you think you have a problem, why don't you stop implanting until you figure out what the problem is.'"
Sid Wolf of the watchdog group Public Citizen thinks both the FDA and Medtronic moved too slowly. He says that their responses remind him of Guidant's device problems in 2005.
Minneapolis Heart Institute doctors, including Hauser, had alerted Guidant to device failures, and the doctors later accused the company of refusing to acknowledge the problems publicly.
Wolf sees a similarity in the events prompting Fidelis leads to be taken off the market.
"When I saw the announcement that this was being taken off, and the horrible self-congratulatory statements that were being made both by the FDA and Medtronic, 'We've done a much better job here than we'd done with Guidant,' I said to myself, I doubt that that's the case. And the more that one looks into this, it starts smelling like the Guidant thing," says Wolf.
But both the FDA and Medtronic say it's not realistic to pull thousands of products from the marketplace with limited data.
Medtronic spokesman Rob Clark says the company did hear reports from such individuals that had stopped using the Fidelis leads, because they had seen a number of injuries.
But Clark says Medtronic also looked at other medical centers, which had done hundreds of Fidelis lead implantations without a hitch. The overall picture wasn't clear.
"Often when a design issue or a manufacturing issue is associated with a product, you will see that playing out across all centers, and not just pockets of centers," Clark says.
That's an assessment with which a number of experts agree. Dr. William Maisell is director of the Medical Device Safety Institute at Beth Israel Deaconess Medical Center. He says what was important for Medtronic to ascertain was not the number of failures on its hands, but the rate of failures.
Maisel favored a recall for the Medtronic leads. But in some ways, he thinks letting patients and doctors make informed choices about using the product is even more important than the recall itself. He gives this example.
"With the Fidelis, the fracture rate is 2.3 percent, but it's also one of the smallest and thinnest leads on the market," says Maisel. "So I can imagine a clinical situation where I might be willing to accept a higher fracture rate on a lead in exchange for its very thin and small, size, if I had a patient or a vessel that was very thin, and that was the only lead I could fit down there."
Daniel Schultz, the director of the FDA's device center, says in the end, a lot of factors have to be considered in any recall. He says in the Medtronic case, the dramatic tipping point was hard to find.
"It's not always black and white, where you get to a line and say 'Aha, it's clear, it's crystal clear,'" says Schultz. "Many times it's going from white through this gray zone, of weighing the various consequences and deciding when to make the decision."
Schultz says one way to make that decision easier going forward is for companies like Medtronic to gather better data on leads implanted in patients, so that problems can be identified at an earlier stage.
Some observers say that's something the FDA itself should mandate. Schultz gave no indication that's likely.