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Friday, Aug 13, 2004

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International

When stents fail, surgeons scramble

By Jeffrey Krasner

It was a routine operation to unclog a patient's coronary artery using one of the hottest products ever to hit the market. But moments after the insertion of a Taxus stent, the surgery became a desperate, failing race to save the patient's life.

The tiny balloon used to position the stent would not deflate. The patient, awake through the procedure, began to suffer severe chest pain. His doctors scrambled to improvise. Working through an incision in the groin, they tried to over-inflate the balloon, hoping it would pop. They snaked 20 different wires through the body to try to burst it, but that failed, too. At one point, they yanked on the equipment so hard a piece broke off, leaving the balloon trapped inside.

Blood flow became so weak doctors performed cardiopulmonary resuscitation and put the patient on a heart-lung machine. Still improvising, they manoeuvred a second balloon inside the stent and inflated it, rupturing the first. But it was too late. "The patient's blood pressure started to drop and the decision was made with the family present to withdraw all life support. The patient was declared dead... " according to a May 24 report in a database maintained by the U.S. Food and Drug Administration (FDA).

Recalls begin

Five weeks later, Boston Scientific Corp. began the first of three recalls of its Taxus stent; the most recent was on August 5. Malfunctions have led to three deaths and 47 serious injuries. The patient's story is one of 186 FDA reports which are filed by doctors, hospitals, or the device maker when there is a malfunction.

The reports, which cover the period between April and mid-July, show that in numerous cases of stent balloon failures, physicians worked around the problem without hurting the patient.

The Taxus stent had fuelled Boston Scientific's growth into a big life sciences company. The distress has been clear and swift. Since the first recall, on July 2, its stock price has fallen 22 per cent, reducing its market value by about $8 billion. The recall, when an additional 3,000 Taxus stents were pulled, can only further undermine investor and doctor confidence in the company. What has not been as visible is the human cost of the malfunctions.

A review of these cases provides a rare glimpse at the drama inside the operating room when the stent balloons malfuntioned and how routine procedures turn suddenly into painful life-and-death struggles.

"It can be very bad when the balloon won't deflate," said a cardiologist . "It's a catastrophic event." He said that in nine years he has never seen a stent balloon failing to deflate. But while the incidence of such malfunctions is rare, they have already affected many people because the use of stents to treat heart disease has skyrocketed. In 2002, some 1.2 million patients in the U.S. had operations to remove blockages from coronary arteries and implant stents, according to the National Centre for Health Statistics. By contrast, only 329,000 appendectomies were performed the same year, and 193,000 hip replacements.

Addressing concerns

Boston Scientific's chief executive, James Tobin, on August 6 met FDA officials in an effort to allay concerns about the stents and reassure the government watchdog that the stents still on the market are safe. "Patient safety is our paramount priority at Boston Scientific, and we make every effort to ensure that our products are of the highest quality," said a company spokesman.

Stents are tiny wire mesh tubes that are used to keep blood vessels open. Doctors thread the stents into the tiny arteries supplying blood to the heart muscle through an opening in the patient's groin, which gives them access to the large leg artery. The patient is conscious throughout, under a local anaesthetic and mild sedative. When the procedure goes well, it is less invasive and less costly than a coronary bypass, in which veins taken from the leg are grafted on.

Introduced in March, the Taxus stent is coated with a drug that deters tissue growth inside the blood vessel, a problem with older stents that often ended up reclogging the artery and leading to repeat procedures. With this innovation, Taxus rapidly gained 70 per cent of the $4 billion worldwide market for drug-coated stents.

Plagued by a problem

Boston Scientific was poised to dominate its archrival, Johnson & Johnson, which earlier had problems with its new Cypher drug-coated stent. Last year, the FDA issued an advisory warning doctors that the stent was associated with sudden blood clots that caused 60 deaths. For Taxus, the most serious problems have occurred when balloons fail to deflate. But Taxus stents have also been plagued by a problem where the balloons deflate properly, but stick to the drug coating.

That also makes the balloons hard to remove, but it has not created the same medical emergencies because the deflated balloons do not completely block blood flow. In some cases, doctors have had to rush patients into open-heart surgery to remove the inflated balloons, though it is not clear how many. -- New York Times News service

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