Thursday, May 10, 2007

Atrial Fibrillation Ablation: What's Missing?

"Did you attend the AFib Sumnmit?"

"Yeah," I said.

"So what's the answer?"

I paused. What was this person from industry trying to ask me? I pondered his question a bit not sure where he was going. So I gave him my honest answer:

"I dunno," I said, in my most professional tone.

"I don't either," he said. "I mean, we've been hearing about the same thing for the past two years now. All these approaches to afib ablation, lots of these guys getting up there telling us how we should do this: pulmonary vein altral isolation, ganglionic plexus targetting, ablating every little small, fractionated potential everywhere in the left atrium... I mean, what are we doing?"

"I dunno," I said again. "But it does work sometimes..."

"Yeah, but no one has the answer to how to make this procedure easy, reliable, and safe, do they?"

"Well, we're getting better at it - I still have trouble knowing an endpoint to ablation though."

"Exactly. I mean, even the consensus statement for ablation of afib states that terminating afib does not mean you were not effective at ablation saying 'in patients with longstanding persistent atrial fibrillation ... an endpoint of noninducibility of AF does not appear to be feasible or even necessary.' I mean, when do you quit? When all of the atrium is destroyed?"

That got me thinking. I knew that not all of the atrium had to be 'destroyed' to achieve success, but is a carpet-bombing approach or precise creation of an ablation line what is needed? Do we need both approaches, or will one suffice?

These questions are important, in part because industry thinks we need fancy new robots and things to drive catheters around inside the heart. They want us to spend considerable financial, spacial, and temporal commitments to buy theit gizmos to help us drive around in the atrium, yet we still don't know where to go, or what lesion sets we need to achieve the best outcomes. All the "Gee-Wizardly" gizmos in the world will never substitute for careful observation and prospective randomized multi-center trials.

Dr. Eric Prystowsky, in his introductory remarks at the beginning of the AF Summit yesteday, estimated that there will have been 8,473,000 catheter ablation procedures for atrial fibrillation performed in the world between 2000 and 2007. Yet as of now, guidelines have already been published jointly by the Heart Rhythm Society, European Heart Rhythm Asociation, and the European Cardiac Arrhythmia Society that admit that only five randomized clinical trials with different endpoints and comparisons have been performed on a TOTAL of 605 patients. Furthermore, there are wide variations in the reported efficacy and complication rates, and the duration of follow-up has been less than 12 months in all of the studies performed so far.

Fortunately, at least one large, multi-center NIH-sponsored trial, the Catheter Ablation vs Antiarrhythmic Drug Therapy for Atrial Fibrillation (CABANA) Trial, is underway to determine the mortality benefit of catheter ablation compared to drug therapy in a population similar to the AFFIRM population in over 4000 patients. Unfortunately that study is estimated to take five years to complete. But at least it's a step in the right direction.

I just hate saying "I dunno" all the time.


Addendum (5:30 PM MST): I met briefly with Dan Starks from St. Jude Medical briefly today and asked him what he thought about Dr. Prystowky's estimate regarding the number of atrial fibrillation ablation procedures being performed. He stated that last year, St. Jude estimated that about 55,000 atrial fibrillation procedures were performed in the United States. If one assumes approximately 100,000 procedures were perfomed in the world, then the MOST procedures performed from 2000-2007 would likely be closer to 500,000-600,000. Still the point remains, we need more prospective randomized clinical trials, especially trials evaluating the safety, efficacy, and mortality benefit of afib ablation.

1 comment:

Anonymous said...

Please Take Dan Starks word with a grain of salt. Did he hand you a $1000 bill for asking him a question?