Drug Pipeline News Drug Pipeline List

Drug Pipeline News Drug Pipeline List

Medtronic Pulls Defibrillator Wires Off Market October, 2007

Medical-device maker Medtronic Inc. (MDT) is suspending sales of an electrical wire that connects the hearts of 235,000 patients world-wide to the defibrillators implanted in their chests, saying they may have contributed to five deaths.

The wire, called a lead, is prone to fracturing within patients' blood vessels and erroneously dispatching a massive electrical jolt, the Minneapolis company said. This jolt can be uncomfortable at best, and at worst may itself have contributed to one or more of the deaths.

However, Medtronic said it isn't recommending that most patients who have the lead - known as the Sprint Fidelis line of defibrillator leads - have them surgically removed. That is because the risk from the surgery to remove the wires from the veins that carry them to the heart could be more potentially dangerous than that of leaving the leads in, according to medical specialists.

The company is recommending patients who think they have the wires in their bodies should contact their doctors, who can reprogram their defibrillators to better monitor and warn of problems with the leads. While many details remain imprecise - and Medtronic largely refrained from discussing the death cases - this product removal could prove significantly larger in scope than the problems that arose in 2005 involving defibrillators and pacemakers made by Guidant Corp, now part of Boston Scientific Corp. (BSX).

In the wake of the Guidant case and similarly bad publicity concerning safety problems with Merck & Co.'s (MRK) Vioxx painkiller, Medtronic's move suggests how pharmaceutical and medical-device makers are increasingly eager to get out in front of potentially damaging issues.

In an interview, David Steinhaus, medical director of Medtronic's cardiac-rhythm disease management unit, said the company views the defects in the Sprint Fidelis leads "as a very low risk," but "we're being super-cautious and conservative about this."

Medtronic made its decision in consultation with the Food and Drug Administration and an outside group of doctors - including Bruce Lindsay, president of the Heart Rhythm Society, which represents specialists in the field.

"The bottom line is we'll have to follow this and see what the numbers show," said Daniel Schultz, director of the FDA's medical device center. "The difference from a few years ago is we've had a much more cooperative relationship with the company and with the Heart Rhythm Society."

Nevertheless, the admission could hurt Medtronic, which is the world's bigger seller of cardiac-electrical devices, such as defibrillators and pacemakers. It has about 50% of the $6-billion-plus defibrillator market. Although the company said it has yet to be sued over these flaws in the devices, lawsuits could follow as they have after earlier cardiac-device withdrawals.

Cardiologists have long known that leads are more fragile than the devices they're connected to, and in the past, recalls of similar devices have cost companies millions. For example, Medtronic has experienced malfunctions in its heart-device leads in the 1980s and again in 1991, when it issued a safety alert to 20,000 doctors about leads' gradually losing their ability to carry electricity.

There are 268,000 of the Sprint Fidelis leads that were implanted in patients, but it is believed that about 235,000 patients now have them in their bodies. The devices that would use the faulty leads also are known as ICDs (for implantable cardioverter-defibrillator) and CRT-Ds (for cardiac resynchronization therapy-defibrillators). This latter form of complex, hybrid device not only can deliver the massive shock but can also provide extra pumping power in the hearts of patients with congestive heart failure.

Heart defibrillators, along with the electrical leads, are designed to sense when a patient's heart has begun beating too fast, often in the lethal fast-quivering state called fibrillation. The device senses that the heartbeat has gone haywire and the shock, when appropriate, can save a patient's life by propelling the heart back into normal rhythm.

When a Medtronic Sprint Fidelis lead fractures, three things can happen. It can simply beep, alerting the patient to consult his physician immediately. Or it can cause a massive, unnecessary shock akin to getting kicked in the chest by a horse. Third, it can cause the defibrillator battery to deplete, which could cause the device to fail to deliver a necessary life-saving shock.

Medtronic's Sprint Fidelis leads are used only in cardiac defibrillators - or complex devices with defibrillation capacity - and not in conventional pacemakers. Some patients with congestive heart failure use devices that include this defibrillation ability, and those would be among the machines that use the Sprint Fidelis lead.

Medtronic said it plans Monday to send a letter to more than 13,000 physicians world-wide. In part the letter will alert doctors that "we have identified five patient deaths in which a Sprint Fidelis lead fracture may have been a possible or likely contributing factor."

Regarding the deaths, Medtronic officials said some involved inappropriate shocks, without specifying the cause of death. Other of the deaths, the officials said, involved battery depletion such that the defibrillator failed to dispatch an electrical shock when it was necessary to save a patient's life.

The company said it has learned through 30-month performance data that the Sprint Fidelis had begun to fail at a greater rate than that of another top Medtronic lead, called the Sprint Quattro. The company's data showed the Sprint Fidelis maintained 97.7% "viability" at 30 months, compared with 99.1% in the Sprint Quattro. Medtronic said the numbers aren't yet statistically significant, but that "if the current lead fracture rates remain constant, it will become so over time."

Even with a failure rate of 2.3% the problem could far exceed the risk factor in the case of the Guidant heart devices, which was generally expressed in terms of 1 in 1,000, or 1 in 5,000. Medtronic medical director, Steinhaus, said most of the 2.3% failure rate relates to fractures as opposed to other causes. He said that historically fractures have been a concern in leads and that there have been other cases of defibrillators going off inappropriately. In the cases where a beep alerts patients to a problem with the leads, Medtronic says doctors could install a second lead. If there isn't room for a second lead, Medtronic says the doctors could then remove and replace the original lead.

That is a risky operation. Two years ago, a number of heart-rhythm doctors- known as electrophysiologists - recommended patients seriously consider leaving in their Guidant devices. The thinking then was that a small risk of a device failing to work was outweighed by the possibility that removing a defibrillator could also mean in some cases having to surgically remove the lead. Removing a lead is a far more major concern than removing a defibrillator.

Defibrillators are matchbox-sized canisters placed under the skin in the shoulder area. Normally, extracting them isn't difficult. But the wire leads, made of thin polyurethane- or silicone-coated metal alloy, are deployed in a vein and connect the device to the heart. The human body often forms scar tissue around the lead. Thus, removing the lead often means tearing at the scar tissue to remove it. This can lead to what some doctors estimate as a 1% possibility of a tear in the vein or the heart itself, and the possibility of dangerous or lethal bleeding.

In 2004, a Dutch study found that major complications occurred in six out of 82 lead-extraction cases, including two patients who died.

Drug Pipeline News archive:

Drug Pipeline Copyright © 2005- 2018 All Rights Reserved.