Firms in a race to treat high blood pressure

With more than a billion people suffering from hypertension worldwide, companies large and small, from Minnesota to Ireland, are racing to develop devices that treat drug-resistant high blood pressure.

Among the most promising is a system that essentially burns the nerves in the renal arteries and eliminates the need for medicine, a technology known as renal denervation.

Fridley-based Medtronic, the world's largest medical-device maker, was first out of the gate with the system, and is now enrolling patients in a first-ever U.S. trial that includes area hospitals. But St. Jude Medical, based in Little Canada, and Boston Scientific, which has 5,000 Minnesota employees, also have jumped on this technology.

Renal denervation involves a catheter snaked through the femoral artery up to the renal arteries, where it uses heat to deactivate the renal nerves. Analysts say the system is a global market that will reach $3 billion within 10 years.

"It is arguably the biggest market that we have seen in decades for devices," said Thom Gunderson, a senior analyst for Piper Jaffray & Co. "Yet, it appears to be a relatively simple device and relatively simple procedure."

This month, St. Jude Medical announced that its EnligHTN renal denervation system safely and effectively lowered blood pressure at six months. Boston Scientific also announced it will pay as much as $425 million for a California company that has developed a renal denervation system that has been approved for use in Europe and Australia. Medtronic's Symplicity system is on its third trial overall, first in the U.S., and has won European and Australian market approval. It has been used on more than 4,000 patients.

About 1.2 billion people worldwide suffer from high blood pressure; up to one-third of those have hypertension that does not respond to multiple medications.

A key to that happening, Gunderson said, will be whether it continues to be proven safe and effective, whether its effects last over time and whether it proves to be more cost-effective than the sometimes three, four and five medications people take simultaneously for their hypertension.

Hypertension is the most common risk factor for cardiovascular disease and leads to long-term health problems. Treatment-resistant hypertension -- having high blood pressure despite taking three or more medications -- affects about 120 million people worldwide and is connected to heart attack, stroke, heart failure, kidney disease and death.

Hyperactivity of the sympathetic nervous system has been shown to play a role in hypertension. The sympathetic nervous system connects the brain, heart, blood vessels and kidneys and each plays a role in regulating blood pressure.

Doctors have found that reducing the hyperactivity of the sympathetic nervous system may reduce hypertension. Renal denervation does that using a catheter inserted into an artery in the thigh that is snaked up to the renal arteries. The tip of the catheter delivers radio-frequency energy that uses heat to deactivate the renal nerves.

One treatment, no implants

Prof. Stephen Worthley, a cardiologist from the Royal Adelaide Hospital in Australia, has worked on clinical trials for the St. Jude EnlighHTN system. St. Jude's device, which uses multiple electrodes to "shut off" renal nerves, "is very promising," he said.

So promising, he said, that it may someday be studied as a way to treat more patients with hypertension -- even those for whom medication is effective. For now, though, studies have been limited to those whose high blood pressure resists medication.

The procedure has proven to be safe and lowered blood pressure for four out of five people in the study, he said. Not only did it reduce blood pressure within 24 hours of treatment, but St. Jude's study showed that improvement continued after six months. Worthley said the data from Medtronic's study shows results lasting even longer.

Good news, indeed, he said. Still, "even if we find at five years that there was some loss of the effect and maybe we need to repeat the treatment, I don't think that it has to be enduring for us to use this."

When compared to the ongoing cost and potential side effects of using multiple medications, Worthley said, using renal denervation for a broader range of people in earlier stages of hypertension may be worth a look.

More questions

Danielle Antalffy, an analyst who focuses on medical devices for Leerink Swann, acknowledged there is "a lot of excitement" about renal denervation. But, as yet, there is no U.S. market. And the market for the three approved products in Europe -- by Medtronic, Ireland-based Covidien and St. Jude -- really hasn't developed yet, she said.

Part of the reason is a lack of awareness. The European Union also has been slow to agree to pay for it. Antalffy said reimbursement in Germany is set to improve in late 2013, allowing sales to accelerate. More information about which patients receive the greatest benefit from the device should help.

"The reality is, we don't have long-term data," she said.

Still, there is little doubt that medical technology companies large and small see it as having huge potential. Antalffy and Gunderson said there are at least dozens of companies working on such projects right now.