Endovascular Renal Nerve Ablation Safely Reduces BP During Exercise

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After showing for the first time in a randomized trial that catheter-based radiofrequency (RF) ablation of the renal nerves substantially lowers blood pressure in patients with treatment-resistant hypertension, an extension of the same study has shown that the renal denervation procedure also reduces blood pressure during exercise without affecting exercise response. The results appear in the September 6, 2011, issue of the Journal of the American College of Cardiology.

Findings from the main randomized Symplicity HTN-2 multicenter trial were released simultaneously in November 2010 at the American Heart Association Scientific Sessions in Chicago, IL, and online ahead of print in the Lancet. Those results showed that in 106 patients with treatment-resistant hypertension randomized to existing treatment with or without the RF procedure, renal denervation substantially lowered blood pressure (BP) without excess risk of adverse events or serious complications.

Focus on Exercise

In an extension of the same trial, researchers led by Christian Ukena, MD, of University Hospital Saarland (Homburg, Germany), took 28 patients from Symplicity HTN-2 plus an additional 18 with the same inclusion/exclusion criteria and randomized them 4 to 1 to existing treatment with (n = 37) or without (n = 9) renal denervation. The difference between the main trial and the newer extension study was that in the latter trial, researchers assessed the effects of the ablation procedure on physical exercise capacity. Therefore, cardiopulmonary exercise testing was performed in all patients upon randomization (baseline) and after 3 months.   

At 3 months, reductions in systolic BP at rest, at peak exercise, and at recovery were all greater in the renal denervation group than in controls, as was the improvement in heart rate recovery (table 1).

Table 1. Change in Resting and Exercise Measurements at 3 Months

In the renal denervation group, achieved work rate increased by 5 ± 13 work units from baseline (P = 0.029), while peak oxygen uptake remained unchanged. In addition, BP 2 minutes after exercise was significantly reduced by 29 ± 17 mm Hg for systolic BP (P < 0.001) and 8 ± 15 for diastolic BP (P = 0.002). Meanwhile, heart rate at rest decreased after renal denervation (4 ± 11 bpm; P = 0.028), while maximum heart rate and the extent of heart rate increase during exercise were not different.

Controls saw no significant changes in blood pressure, heart rate, maximum work rate, or ventilator parameters after 3 months.

It had been theorized that because sympathetic nerve activity physiologically regulates the response to physical stress, cardiovascular response during exercise might be impaired by renal denervation, the authors write.

However, “our study showed for the first time that renal nerve ablation significantly reduces blood pressure during exercise with improvements in [heart rate recovery] without blood pressure dysregulation, ventilator effects, or chronotropic incompetence,” they conclude. “Our results support the efficacy and safety of [renal denervation] in the treatment of resistant hypertension.”

 

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Source:
Ukena C, Mahfoud F, Kindermann I, et al. Cardiorespiratory response to exercise after renal sympathetic denervation in patients with resistant hypertension. J Am Coll Cardiol. 2011;58:1176-1182.

Disclosures:

• Dr. Ukena reports receiving support from the Ministry of Science and Economy of the Federal State of the Saarland and working at a center that receives per-patient payment for study involvement as part of the Symplicity HTN-1 or HTN-2 study.

 

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• Novel Catheter-Based Treatment Reduces Resistant Hypertension