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Renal Stenting Shows Potential for Marked BP Lowering in Uncontrolled Hypertension

By L.A. McKeown

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Trials of renal artery stenting in patients with uncontrolled hypertension have shown few positive results of late, leaving many to conclude that a conservative, medical therapy approach is best. However, a new study published in the September 2012 issue of Catheterization and Cardiovascular Interventions suggests that renal stenting benefits patients with the most severe hypertension by providing a greater reduction in blood pressure than possible with even the most complex medical therapy.

Investigators led by Michael R. Jaff, DO, of Massachusetts General Hospital (Boston, MA), conducted a multicenter, non-randomized study of 202 patients with substantial renal artery stenosis and uncontrolled hypertension who underwent renal stenting between August 2007 and October 2009. Patients were included if they had blood pressure values greater than 140/90 mm Hg despite maximal doses of at least 2 antihypertensive agents (average 3.4 agents per patient) and renal artery stenosis of at least 60%.

At 9 months, the rate of restenosis (the primary endpoint) as measured by duplex ultrasound and/or angiography, was 10.5%, much lower than the predetermined performance goal of 28.6% (P < 0.0001). In addition, there was a reduction in systolic blood pressure at 1 month that remained at follow-up. However, there was no decrease in the number of antihypertensive medications or change in renal failure, as measured by estimated glomerular filtration (eGFR) rates. Additionally, despite a reduction following renal artery stenting in brain natriuretic peptide (BNP) levels—measured at 24 hours and 30 days post stenting—preprocedure BNP levels were not predictive of improvements in postintervention systolic pressure (table 1).

Table1. Primary and Secondary Endpoints

 

Baseline

1 Month

9 Months

P Value

Systolic BP, mm Hg

162 ± 18

145 ± 21

145 ± 21

< 0.0001a

≥ 3 Medications

70%

68%

66%

0.61

eGFR, mL/min per 1.73 m2

58 ± 21

59 ± 21

57 ± 23

0.38a

BNP, pg/mL

181 ± 297

154 ± 235

–

0.01

a Compares baseline and 9 months only.

Additional analysis to measure change in BNP levels did not show any predictive trend.

Overall, there was 1 death and 2 cases of renal atheromatous embolization that resulted in kidney damage after renal stenting. The 30-day rate of the composite safety endpoint was 1.5%. The overall composite safety endpoint, which also included clinically driven TLR at 9 months, resulted in an event-free rate of 94.8%.

Apples vs. Oranges

Two randomized trials, ASTRAL and STAR have suggested that renal artery stenting offers no benefit compared with optimal antihypertensive therapy. But in a telephone interview with TCTMD, Dr. Jaff said the trials are not comparable to HERCULES.

“Both of those trials were of patients with chronic kidney disease and the goal was to show a reduction in worsening of kidney function,” he said. “We looked at patients with uncontrolled hypertension, so it’s a real apples-to-oranges comparison.”

Dr. Jaff said HERCULES should make clinicians more optimistic about renal stenting, unlike the ASTRAL trial, which had high enough complication rates to lead the study authors to question the widespread use of renal stenting.

“I think [they made] a generalized statement based on flawed data,” Dr. Jaff responded. “What our study suggests is that in patients with truly drug-resistant hypertension and significant renal artery stenosis, renal artery stenting by skilled operators can result in impressive reductions in blood pressure with extraordinarily low complication rates.”

In an editorial accompanying the study, William B. Hillegass, MD, MPH, of the University of Alabama at Birmingham (Birmingham, AL), added that both ASTRAL and STAR included patients not expected to benefit from renal stenting and specifically excluded those with high a priori likelihood of benefit. He argues that they “should be viewed as trials largely assessing extension of [renal artery stenting] therapy to off-target patient groups of unknown benefit.”

Better Than Anything Else Out There

Dr. Jaff contended that performed correctly, renal stenting in patients like those in HERCULES can lead to an almost 50 mm Hg reduction in blood pressure. “There isn’t a combination of medications in a trial I’m aware of that has shown a benefit like that,” he said. “Even the renal denervation trials that have been published don’t show that magnitude of reduction.”

In addition, Dr. Jaff said he is confident that 2-year data from HERCULES, scheduled for publication soon, will show sustained benefit of renal stenting beyond initial follow-up.

According to Dr. Hillegass, without properly conducted randomized trials, observational studies such as HERCULES play a role in helping to define characteristics that may predict which patients will benefit most. Despite some early promise for BNP however, Dr. Jaff said the HERCULES study shows “the predictive value of BNP is dead. So we don’t have a good biomarker, . . . we’re left with clinical clues.”

The best bet for randomized data in patients similar to the HERCULES cohort will likely come from the ongoing NHLBI-sponsored CORAL trial and a few small European trials similar to HERCULES, Dr. Jaff said.

Study Details

Renal stenting was performed using the RX Herculink Elite Renal Stent System (Abbott Vascular, Santa Clara, CA). All patients received aspirin 325 mg once daily and clopidogrel either 75 mg orally once daily for 4 days before the procedure or as a single loading dose of 300 mg orally within 24 hours before the procedure. Following stent placement, aspirin was continued for a minimum of 12 months and clopidogrel for at least 4 weeks.

 

Sources:
1. Jaff MR, Bates M, Sullivan T, et al. Significant reduction in systolic blood pressure following renal artery stenting in patients with uncontrolled hypertension: Results from the HERCULES trial. Catheter Cardiovasc Interv. 2012;Epub ahead of print.

2. Hillegass WB. Benefit of renal artery stenting: Is on-target therapy the observational bias? Catheter Cardiovasc Interv. 2012;Epub ahead of print.

 

 

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Disclosures
  • Dr. Jaff reports serving as a non-compensated advisor for Abbott Vascular, Cordis Corporation, Covidien/eV3, Medtronic, and VIVA Physicians.
  • Dr. Hillegass reports no relevant conflicts of interest.

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