Atrial Fibrillation Treatment Success Rate More Than Doubles When Renal Artery Denervation Is Added To Afib Catheter Ablations
By Peggy Noonan
September 25, 2012
- Summary: New research shows that when a procedure called renal artery denervation is added to atrial fibrillation catheter ablation, treatment success more than doubles.
- Reading time is approximately 4-5 minutes
Atrial fibrillation treatment success more than doubled when patients with medication-resistant high blood pressure and symptomatic (not asymptomatic) atrial fibrillation were treated with a procedure called “renal artery denervation,” according to a research report in the Journal of the American College of Cardiology.
Renal artery denervation is a minimally invasive catheter procedure that uses radiofrequency energy to zap two types of nerves in the kidney that affect the nervous system.
“Atrial fibrillation is the most common arrhythmia,” says study coauthor Jonathan S. Steinberg, MD, director of the Valley Health System Arrhythmia Institute and Professor of Medicine at Columbia University College of Physicians & Surgeons, in New York. It can lead to debilitating symptoms and is the most common cardiac cause of stroke. But afib “is very difficult to control with medications” and some subsets of afib patients, “such as those with persistent arrhythmia, are much more difficult to treat.”
Why attack kidney nerves to help heart function?
Because “the nerves that help control renal [kidney] function are also involved in blood pressure control,” Steinberg explains, and because “hypertension [high blood pressure] is the most common cardiovascular cause of atrial fibrillation.”
He and his coauthors knew from other recent studies focusing on people with drug-resistant chronic high blood pressure that when those renal nerves were targeted for treatment with renal artery denervation, the procedure worked to bring blood pressure under control.
They also knew that high blood pressure increases atrial stretching, which promotes atrial fibrillation. Since the same nerves that renal artery denervation targeted for blood pressure control also play a role in arrhythmia, could the same procedure that worked to bring chronic high blood pressure under control also work for afib?
To test that theory, 27 patients with drug refractory (not responsive to medication) hypertension and paroxysmal or persistent atrial fibrillation were enrolled. For this study, drug refractory was defined as:
- in Hypertension — despite having taken three or more blood pressure medicines, including a diuretic, patients’ systolic (top number) blood pressure reading remained at 160 mm Hg or higher.
- in Atrial fibrillation — despite having taken two or more rhythm control drugs, the patient still had afib and had been referred for catheter ablation.
Traditional catheter ablation for afib, called pulmonary vein isolation (PVI), is an attractive and effective treatment for afib that does not respond to medication, especially with experienced operators and centers, Steinberg says. But not all patients respond to this treatment, and some need to have the procedure repeated.
For this small randomized clinical trial, 14 patients were treated with pulmonary vein isolation alone and 13 were treated with the same PVI procedure plus renal artery denervation (at the same time).
Over a year of follow-ups, “we found a substantial incremental benefit when renal artery denervation was performed as opposed to standard ablation alone,” Steinberg says.
The renal artery denervation group’s success rate was more than twice as high as the PVI ablation-only group. The study reports these statistics:
- 69% of the PVI plus renal artery denervation group (9 of the 13 patients) were afib-free, compared to
- 29% of the PVI-only group (4 of the 14 patients)
Hypertensive patients had “markedly improved blood pressure control,” Steinberg notes, and “no complications occurred.”
Patients who were treated with PVI alone had a high risk of afib recurrence. The researchers noted that this was likely due to atrial remodeling from persistent afib and hypertension. Since optimized blood pressure control could impact the substrate and prevent afib recurrence, they reasoned that renal artery ablation “could influence the recurrence rate of AF after PVI.”
This offers the “potential for an antiarrhythmic effect superior to medications,” they add. And the results show that the effect high blood pressure has on afib is “partially reversible” if patients also have PVI.
“We believe that renal artery nerves may be involved in the development of atrial fibrillation,” Steinberg says. “Denervation may be an exciting and highly innovative new treatment technique.”
In an accompanying editorial, University of Pennsylvania electrophysiologist Ralph Verdino, MD, poses some interesting questions for his fellow electrophysiologists to ponder:
Should renal artery denervation be part of ablation for all patients undergoing catheter ablation for the treatment of AF? Or should it be limited to those with hypertension or only those with drug-refractory hypertension? Should renal artery denervation be performed instead of pulmonary vein isolation? And have we been targeting the wrong organ?
These are important questions that this small study was not set up to answer, however Verdino says other larger studies in progress now may help provide some answers.
One pivotal study in final preparations now will test the use of renal artery denervation alone to treat atrial fibrillation. This large-scale, multicenter, randomized clinical trial will be coordinated and directed by Steinberg’s institution. Its goal is development of renal artery denervation as an alternative and less invasive treatment for Afib, says Steinberg.
Keep in mind that this was only a small study and only had one year of follow up, so we don’t really know the long-term impact of such a procedure.
But Verdino’s questions are quite interesting and compelling, and are something that patients and caregivers may want to consider in the future. If the studies do prove that renal artery denervation alone (without PVI catheter ablation) works, then this could be a promising way to treat atrial fibrillation as well as hypertension. And if this new approach of attacking afib via the kidneys instead of the heart works, we may also wonder what other organs or other novel approaches might work.
Another really interesting question posed by Verdino was whether better control of hypertension using medications could actually decrease afib recurrence after catheter ablation, or even substitute for catheter ablation. That’s certainly food for thought for those with afib and high blood pressure.
For more information, see:
- A Randomized Comparison of Pulmonary Vein Isolation With Versus Without Concomitant Renal Artery Denervation in Patients With Refractory Symptomatic Atrial Fibrillation and Resistant Hypertension, Journal of the American College of Cardiology, published online September 5, 2012
- Catheter Ablation for the Treatment of Atrial Fibrillation. Have We Been Targeting the Wrong Organ?, Editorial Comment, Journal of the American College of Cardiology, published online September 5, 2012
- Renal Denervation Shows Surprising Promise in Patients with Atrial Fibrillation, EP Lab Digest, September 7, 2012
- Renal Denervation Achieves Significant and Sustained Blood Pressure Reduction, Study Suggests, ScienceDaily, August 7, 2012
- Catheter-based renal denervation, European Society of Cardiology