Symplicity Studies Support Safety, Efficacy of Percutaneous Renal Denervation

AMSTERDAM, The Netherlands—Blood pressure reductions in patients who undergo renal denervation for treatment-resistant hypertension persist through 3 years, according to data from Symplicity HTN-1 presented on September 3, 2013, at the European Society of Cardiology Congress. Findings from the Global Symplicity Registry, presented on September 2, provide further evidence that the procedure is safe and effective.

Positive Long-Term Results from HTN-1

In all, 88 of 150 patients in Symplicity HTN-1 completed the full 3-year follow-up, said investigator Henry Krum, MBBS, PhD, of Monash University (Melbourne, Australia). Compared with patients with incomplete follow-up, this group was more likely to have hyperlipidemia at baseline (71% vs. 48%; P = 0.007), but other clinical characteristics were similar.

At baseline, systolic BP was 175 ± 17 mmHg and diastolic BP was 98 ± 15 mmHg in the 3-year follow-up group. Improvements seen early after renal denervation were sustained through 2 and 3 years (P < 0.01 vs. baseline for both; table 1).

Table 1. Symplicity HTN-1: Change in Office BP Over Follow-up (n = 88)

By 3 years, approximately half of patients had reached the systolic BP target of < 140 mmHg. Greater than 10 mmHg reduction in systolic BP was seen in 93% of patients.

Baseline renal function did not predict response to renal denervation at 2 and 3 years, nor did age or diabetes status. Heart rate did not change over time, Dr. Krum reported, “remembering that this in the setting of a 30-mmHg drop in blood pressure.” Renal function changed over time, he said, but the change is possibly due to the natural history of the disease.

Safety events over 3 years included 4 possible renal artery stenoses: 2 hemodynamically stable and requiring no intervention (during months 0-6 and > 6-18), 1 nonsignificant and requiring no intervention (during months > 6-18), and 1 stented without sequelae (during > 18-36 months). Thirteen patients required hospitalization for hypertensive episodes, and 4 had hypotensive episodes. There were 3 deaths, including 1 fatal MI, 1 sudden death, and 1 cardiorespiratory arrest.

Nerve Regrowth Not a Problem

The durability of BP lowering with percutaneous renal denervation “suggests that nerve regrowth and functional reinnervation do not translate into a clinically significant loss of blood pressure-lowering efficacy of the procedure (at least at this time point and indeed if it occurs),” Dr. Krum concluded. “Certainly further longer-term study of these patients is required.”

Discussant Thomas R. Lüscher, MD, of University Hospital Zurich (Zurich, Switzerland), said that based on transplant patients and experimental studies “there was always a concern that there may be nerve regrowth after a while, and this seems not to occur up to 3 years. This is extremely encouraging.” Moreover, the treatment effect seems consistent across studies, he added.

Global Registry Also Positive

Michael Böhm, MD, PhD, of the University of Saarland (Homburg, Germany), presented an oral abstract on 1,158 patients enrolled in the Global Symplicity Registry.

According to a Medtronic (Minneapolis, MN) press release, major complications or serious adverse events related to delivery of radio frequency energy included 1 procedural dissection (0.09%) and 1 reintervention at 6 months (0.09%). Patients with systolic BP ≥ 180 mmHg at baseline saw improvements at 6 and 12 months, as did those with systolic BP ≥ 160 mmHg ( ≥ 150 mmHg with diabetes) at baseline (table 2).

Table 2. Global Symplicity Registry: Changes in Office BP vs. Baseline

Average reductions in ambulatory blood pressure measurements (n = 132) were -10/-5 mmHg from baseline to 6 months (P < 0.0001).

 

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Sources:
1. Krum H. Symplicity HTN-1: Catheter-based renal artery denervation provides safe and durable blood pressure reduction: Complete 3 year results from Symplicity HTN-1. Presented at: European Society of Cardiology Congress; September 3, 2013; Amsterdam, The Netherlands.

2. Böhm M. The blood pressure lowering effects of renal denervation in a real-world population of patients with uncontrolled hypertension: Early outcomes from the Global Symplicity registry. Presented at: European Society of Cardiology Congress; September 2, 2013; Amsterdam, The Netherlands.

3. Medtronic reports strong safety and sustained clinical efficacy results of the Symplicity Renal Denervation System from the Global Symplicity Registry [press release]. Published: September 2, 2013. Accessed: September 2, 2013.

 

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