Two-Year Data for Medtronic's Symplicity HTN-1 Data Presented at TCT

October 22, 2012—Medtronic, Inc. (Minneapolis, MN) announced new results from the Symplicity HTN-1 clinical trial that is investigating the safety and efficacy of renal denervation. The expanded 2-year cohort data were presented for the first time at the TCT 2012: Transcatheter Cardiovascular Therapeutics conference in Miami, Florida.

According to Medtronic's press release, Symplicity HTN-1 was a series of pilot studies at 19 centers in Australia, Europe, and the United States. The open-label cohort study enrolled 153 patients with systolic blood pressure ≥ 160 mm Hg while taking ≥ 3 antihypertensive drugs at optimal dosages, including a diuretic. Most patients will be followed to 1 year and a subgroup of patients is being followed semi-annually to 3 years after renal denervation with the Symplicity system.

As summarized by Medtronic, the data showed patients who received renal denervation treatment with the Symplicity system experienced a mean blood pressure reduction of -29/-14 mm Hg [P < .01] at 24 months (n = 105). These data expand the total number of patients from the number previously reported at 24 months (n = 59) from this clinical trial. The safety of renal denervation with the Symplicity system was also maintained at 24 months. The Symplicity system is available only for investigational use in the United States, the company advised.

Responder rates (defined as a ³10 mm Hg reduction) among patients completing follow-up increased from 69% at 1 month to 82% at 24 months. Safety follow-up at 24 months demonstrated continued stable renal function with no new episodes of hypotension, orthostasis, or renal artery stenosis related to the renal denervation procedure; adverse events due to comorbid diseases such as infection and nonrenal surgical complications were reported.

Pulse pressure improved significantly following treatment with the Symplicity system, with a reduction of -15 mm Hg [P < .01] from baseline for the expanded patient cohort (n = 105) at 24 months. The company noted that pulse pressure, which is the numeric difference between systolic and diastolic blood pressure, may have independent predictive value beyond absolute blood pressure measurements alone in terms of cardiovascular complications, especially in older patients. It may be important to evaluate changes in pulse pressure as well as systolic and diastolic blood pressure when assessing the efficacy of antihypertensive therapy.

Additionally, Medtronic stated that in this same analysis, there were 34 patients available for follow-up at 36 months versus 24 patients available at 3 years in the previously reported data. These 34 patients experienced a mean blood pressure reduction of -31/-16 mm Hg [P < .01] at 36 months. For the patients in this analysis who were available for follow-up at 36 months, there was a -16 mm Hg [P < .01] reduction in pulse pressure after treatment with the Symplicity system. Responder rates among patients completing follow-up increased to 94% at 36 months.

The Symplicity renal denervation system was launched commercially in April 2010 and is currently available in parts of Europe, Asia, Africa, Australia, and the Americas. It is not approved by the US Food and Drug Administration (FDA) for commercial distribution in the United States. In August 2011, the FDA granted Medtronic approval for the protocol for SYMPLICITY HTN-3, the company's United States-based clinical trial of the Symplicity renal denervation system for treatment-resistant hypertension.

Markus Schlaich, MD, who is head of Hypertension & Kidney Disease at the Baker IDI Heart and Diabetes Institute in Melbourne, Australia, commented about the data in the company's announcement.

“These clinical trial results provide important evidence and confidence for physicians that renal denervation with the Symplicity system continues to be safe and effective in reducing blood pressure over time in patients with treatment-resistant hypertension, who are at high risk for various cardiovascular events,” stated Dr. Schlaich. “These data in nearly twice the number of patients previously reported at 2 years in this trial provide us with a better understanding of the patient response over time and add to the growing body of evidence supporting the safety and sustained blood pressure reduction of renal denervation treatment with the Symplicity system.”