Cook Medical’s Zilver PTX was a good stent, as stents go; and as stents go, it went. The Bloomington, Indiana company recalled the peripheral device worldwide last month after reports that it could become detached from its delivery system, and now the FDA has declared the recall class I, meaning that use of Zilver PTX is potentially lethal.
Given Cook's huge hopes this is a disaster, and stands in poignant contrast with the fanfare that had surrounded the US launch of the drug-eluting stent (DES), the only device of its kind, last November. The company’s insistence that the fault lies with the delivery catheter rather than Zilver PTX itself will go some way towards mitigating the reputational damage to the stent, but a global recall cannot be shrugged off.
The self-expanding stent is inserted into the narrowed region of the femoral artery using a catheter, and once in place leaches paclitaxel into the epithelium to prevent restenosis. It appears that the tip of the inner catheter can sometimes break off during implantation.
The class I label is justified: the problem appears to have led to one death already. Cook says it has received 13 complaints from doctors regarding breakage; in addition to the one patient death, another unspecified adverse event resulted from the breakage.
If the tip of the catheter breaks off inside a patient’s vein it can block the vessel or cause thrombosis, perhaps causing a heart attack or stroke, or necessitating retrieval surgery or even amputation of the leg. Cook says that the rate of failure is 0.043% and points out that patients already implanted with the device are not at any risk, but even without the recall the safety concerns would have hit sales. Since Zilver PTX was launched in the US at the end of last year 84 medical institutions have started using it.
The private company says it has altered its manufacturing to fix the problem, but it will take time to get the FDA to sign off on the new system. The recall will also put the kybosh on Cook's plans to roll out more sizes of the device throughout 2013.
One factor in Cook’s favour is the paucity of alternatives. The other possible options for treating the peripheral arterial disease include balloon angioplasty, bare-metal stents, drug therapy or surgical bypass (Cook has US peripheral drug-eluting stent market on a Zilver platter, November 16, 2012).
The interruption to sales of the stent will have a serious effect on Cook’s revenue, estimated at $2bn worldwide. The company had been expecting Zilver PTX to be one of its best selling products. Zilver PTX will almost certainly regain its place on the interventional cardiologist’s shelf, but for Cook yesterday is not soon enough.