Medtronic (NYSE:MDT) said its Symplicty renal denervation device failed to meet the efficacy endpoint in a U.S. pivotal trial, Symplicity HTN-3, prompting it to suspend enrollment in its other Symplicity trials around the world and to say that a writedown of its renal denervation assets is likely.

"Symplicity HTN-3 met its primary safety endpoint related to the incidence of major adverse events one month following randomization and renal artery stenosis to six months," co-principal investigator Dr. Deepak Bhatt, of Boston’s Brigham & Women’s Hospital, said in prepared remarks. "Importantly, however, the trial did not meet its primary efficacy endpoint."

"While it’s disappointing the trial did not meet its primary efficacy endpoint, this is the most rigorous renal denervation clinical trial conducted to date, and the first of its kind to include a sham-control group. We look forward to advancing these data into the peer-review process and will submit these findings for presentation and scientific discussion at an upcoming scientific congress," added co-principal investigator Dr. George Bakris of the University of Chicago Medicine.

Medtronic said it will assemble an independent panel to recommend next steps for its global hypertension program, "as well as provide advice on continued physician and patient access to the Symplicity technology in countries with regulatory approvals," according to a press release.

Enrollment in 3 other renal denervation trials – Symplicity HTN-4 in the U.S., HTN-Japan and HTN-India – will be suspended while the Fridley, Minn.-based medtech titan informs patients and physicians of the Symplicity HTN-3 results. Medtronic will still sell the Symplicity device in markets where it’s already won approval, according to the release. Post-market registry studies and trials investigating indications other than high blood pressure will continue, Medtronic said.

"We are disappointed that the clinical trial failed to meet its primary efficacy endpoint," chief medical officer Dr. Rick Kuntz said in prepared remarks. "We believe this course of action is the most prudent and will help us thoroughly evaluate these findings and determine the appropriate next steps for renal denervation therapy. We would like to thank the patients and investigators for their participation in the trial and their important contribution to the field of hypertension research."

Medtronic reiterated its outlook for fiscal 2014 for earnings per share of $3.80 – $3.85 on sales growth of 3% to 4% and adjusted EPS growth of 6% to 8%.

The implications of the Symplicity HTN-3 outcome are unclear for St. Jude Medical (NYSE:STJ), which called off the Enlightn IV trial of the next generation of its renal denervation technology last month, just a few months after it began. The trial of St. Jude’s multi-electrode Enlightn device was slated to enroll about 590 patients between the ages of 18 and 80 with high blood pressure that isn’t well-managed with drugs.

But concerns that Medtronic’s Symplicity device could reach the U.S. market led St. Jude to spike the Enlightn IV trial, which it launched in May. Having another technology on the market would make it tough to interest patients in the trial, which might see them enrolled in the sham arm of the study, a company spokeswoman told MassDevice.com at the time.

St. Jude did not immediately respond to a request for comment.