Medical Device Daily Associate Managing Editor

Medtronic (Minneapolis) said that it has received FDA approval for the Micro-Driver coronary stent system, a bare metal system designed specifically to perform in small vessels and tortuous anatomies.

This cobalt alloy stent is the first bare metal stent for small vessels with an indication for new or untreated vessels (a de novo indication), addressing an important need in the treatment of coronary artery disease.

Why keep rolling out bare-metal stents when the drug-eluting stent systems seem to have claimed the lion's share of the stent space?

“There are some physicians who simply prefer bare metal stents,” said Medtronic Vascular (Santa Rosa, California) spokesperson Scott Papillon.

And there are many patients “for whom bare metal actually is a preferred stent,” he told Medical Device Daily. “Some patients can't tolerate the dual antiplatelet therapy that's required with drug-eluting stents.”

Sean Salmon, vice president and general manager of Medtronic Vascular's coronary business, noted the specific benefit of this stent. “A stent can be effective only if it gets to the lesion. Micro-Driver is highly deliverable and is designed specifically for ease-of-use in these types of patients,” he said. “We believe there always will be an important role for bare metal stents, especially when they can address specific clinical needs as this stent does.”

Papillon noted that the Driver stent is already being used in Europe as part of the company's next-generation Endeavor DES, and includes the smaller sizes of the Micro-Driver which have been available in Europe since June 2003 (Medical Device Daily, June 18, 2003).

Based on the Medtronic Driver stent platform, the Micro-Driver stent has a rounded, modular design for excellent deliverability. The ultra-low crossing profile helps physicians access the difficult-to-reach lesions often encountered in patients with small vessels. These patients otherwise could have limited treatment alternatives, according to Michael Ball, MD, St. Vincent Hospital (Indianapolis) and the Heart Center of Indiana.

“This stent fulfills an essential need that we have in cardiology,” said Ball, a clinical investigator in the Micro-Driver clinical trial and study's top patient enroller. “When you do small vessel stenting, you want the stent to be small and you want it to be flexible. That's the whole idea behind Micro-Driver. It conforms well to the anatomy and allows you to take care of more lesions. I think more patients should be able to benefit from this technology.”

Made from an advanced cobalt alloy that is more radiopaque than stainless steel, the Micro-Driver stent will replace the Medtronic S660 stainless steel model. Micro-Driver is available in diameters of 2.25 mm, 2.50 mm and 2.75 mm, and lengths of 8, 12, 14, 18, and 24 mm, and on both over-the-wire and Medtronic MX(2) delivery platforms.

Even with the rapid acceptance of drug-eluting stents (DES) during the last three years, bare metal stents still play a critical role in the medical practice of interventional cardiologists. Many physicians choose bare metal stents for patient care in small-vessel cases, and the Micro-Driver stent offers them an important treatment option, the company said.

In October 2005, Medtronic reported that it had filed its first premarket application (PMA) module for Endeavor with the FDA (MDD, Oct. 12, 2005). This was the first of four PMA modules the company will submit to the FDA, leading to what it anticipates will be U.S. approval of the Endeavor DES in 2007.

While Papillon could not comment on whether the Micro-Driver technology would be incorporated into the U.S. launch of the Endeavor system, he did note that there is definitely a need for the smaller sized stents associated with the product.

“Some doctors need [these smaller devices], especially for patients who have really tortuous anatomy or diabetes. There's a very definite need in this size area."