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- Ralph J. Verdino, MD⁎ ()
- ↵⁎Reprint requests and correspondence:
Dr. Ralph J. Verdino, Hospital of the University of Pennsylvania, 3400 Spruce Street, 9th Floor, Founders Pavilion, Philadelphia, Pennsylvania 19104
When I think back on my decision to pursue a career in cardiac electrophysiology, I recall how much I enjoyed this field in which almost every disease state and its specific treatment seemed logical. I was fascinated by the physiology of electrophysiology, how arrhythmias were generated, and how an understanding of pathophysiology led to curative procedures. I recall the joy of my first catheter ablation of an accessory pathway, how the surface electrocardiogram normalized within seconds of applying radiofrequency energy and, more importantly, how the supraventricular tachycardia that had plagued the patient for years was no longer able to be induced by pacing maneuvers. I remember the first day that I ablated an atrial tachycardia with a combination of activation mapping and pace mapping and how an almost incessant arrhythmia was silenced and sinus rhythm reigned. And I recollect feeling confident that the chance of recurrent atrial flutter was very low when I confirmed bidirectional block in another patient for the first time after a tricuspid isthmus ablation.
When I learned that catheter ablation procedures were being developed as a curative treatment for atrial fibrillation (AF), I was intrigued but also suspicious. Sure, I ablated the His bundle for rate control of this increasingly prevalent arrhythmia, but using a catheter to forever silence the atrium from returning to a chaotic electrical storm seemed implausible. Cox et al. (1) reported high success rates of the surgical Maze procedure, but many patients required permanent pacemakers. I wondered about the meticulousness of the patient follow-up and recall seeing a patient or 2 in consultation who were no longer in AF but instead in an incessant atypical atrial flutter months or years after the procedure. I recall an abstract by Swartz et al. (2) who used catheters to replicate the knife of the surgeon creating a Maze but remember that the procedure was prohibitively long and fraught with complications and heard that long-term success rates were not outstanding. I remember the figure on the cover of the Journal of Cardiac Electrophysiology reporting the first successful catheter ablation of AF produced solely by a series of contiguous ablation lines in the right atrium (3). How could an arrhythmia caused by multiple wavelets of re-entry be cured by this procedure? The report by Haissaguerre et al. (4) of ablating triggers of AF most often found in the pulmonary veins brought back to me a sense of electrophysiological logic. It seemed reasonable to ablate the triggers in patients with paroxysm of AF rather than targeting the large area of atria responsible for its maintenance, and as the procedure evolved from ablating focal triggers to pulmonary vein isolation, it has become more successful with a smaller chance of recurrence.
Catheter ablation for the treatment of AF has become a very commonly performed and widely accepted procedure. In 2001, the American College of Cardiology/American Heart Association/European Society of Cardiology guidelines (5) listed non-pharmacologic treatment almost as a passing thought, reserved only for patients with AF and structurally normal hearts who failed multiple antiarrhythmic medications. In the 2006 revision of those guidelines (6), catheter ablation became the second-line therapy for all patients requiring treatment for AF, from patients with normal hearts to those with hypertension to those with coronary artery disease and congestive heart failure. At my hospital, catheter ablation for the treatment of AF is the most commonly performed procedure in our 5 electrophysiology laboratories, more commonly performed than ablation of all other supraventricular arrhythmias, including atrioventricular nodal re-entry tachycardia, Wolff-Parkinson-White syndrome, atrial tachycardia, and atrial flutter, combined. Published success rates and long-term freedom from AF with catheter ablation in patients with paroxysmal and non-paroxysmal AF have been reported as 70% to 80% in some centers. Yet due to our reliance on patient symptoms and arrhythmia-monitoring of relative short duration, recurrence of AF is likely much more common than that reported in the published data and quoted at national conferences. A recent report of long-term success in patients with paroxysmal and non paroxysmal AF ablated at a prestigious institution was dismal at 23% at 6 years of follow-up (7). The techniques for ablation continue to vary widely around the country and the world from primarily pulmonary vein isolation and ablation of non-pulmonary vein triggers to creation of lines of block to targeting complex fractionated electrograms.
In this issue of the Journal, Pokushalov et al. (8) describe their attempt to increase the success rate for catheter ablative treatment of AF by combining their standard procedure of pulmonary vein isolation and focal trigger ablation with renal artery denervation in patients with AF and drug-refractory systemic arterial hypertension. Renal artery denervation has recently been performed for the treatment of drug refractory hypertension, and the success rates after the application of radiofrequency energy into the renal arteries in decreasing systolic and diastolic blood pressure are impressive (9). By combining these 2 procedures in 13 patients randomized in the study, the authors more than doubled the success rates defined as <30 s of AF during 9 months of follow-up (from 3 months post-ablation to 1 year from the procedure). The authors found that the success rate for the combined procedure was achieved in 9 of the 13 patients (69%) treated with pulmonary vein isolation and renal artery denervation as compared with only 4 of 14 patients (29%) in those treated with only pulmonary vein isolation. As expected, there was also a significant decrease in both systolic and diastolic blood pressure in those treated with renal artery denervation. Although the study cohort is small and one can certainly question the comprehensiveness of documenting arrhythmia recurrence because continuous ambulatory monitoring was not used in this study, the findings are nevertheless impressive. One might wonder why the success rate of those 14 patients undergoing only cardiac ablation was so dismal with a single procedure. Many questions will arise with regard to the thoroughness of the atrial ablation procedure itself, and because many electrophysiology laboratories use different techniques, those who regularly ablate AF will likely find fault with some aspect of the procedure used in this study. Some might ask: should lines have been drawn, fractionated electrograms been targeted, isoproterenol or adenosine been administered, and other questions relating to the procedure. Yet, this same procedure was reportedly used in the 13 patients who had additional ablation lesions delivered in the renal arteries, and their success rates were markedly improved, certainly in line with or better than published results after a single procedure without the use of antiarrhythmic drugs.
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? This small study does not attempt to answer these questions; rather it offers more opportunity to return physiology to the electrophysiology of AF. Larger studies currently underway might help to answer some of these questions. However, this study actually raises other questions that I suspect will not be answered any time soon. Should renal artery denervation be performed instead of pulmonary vein isolation? And have we been targeting the wrong organ? This study also allows one to wonder whether improved pharmacologic control of hypertension can decrease AF recurrences after catheter ablation of AF or even instead of performing this procedure. Maybe with better control of hypertension, however we physiologically achieve it, we can indeed improve the success rates of catheter ablation of the atria or decrease the need to ever perform this procedure in many patients.
Dr. Verdino has reported that he has no relationships relevant to the contents of this paper to disclose.
↵⁎ Editorials published in the Journal of the American College of Cardiology reflect the views of the authors and do not necessarily represent the views of JACC or the American College of Cardiology
- American College of Cardiology Foundation
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- European Heart Rhythm Association, Heart Rhythm Society
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