Atrial Fibrillation: 3 Notable Studies, 3 Important Questions
In treating atrial fibrillation (AF), this year has witnessed some real excitement. And not all the good news has to do with new pills. Recently, there has been a flurry of encouraging and objective news on ablating AF. Here are some comments on three notable studies that address three important questions:
1. What are the “long-term” success rates of AF ablation?
On this important question comes an American Heart Association (AHA) abstract from the highly-regarded lab of Dr. Karl-Heinz Kuck in Hamburg. They report on a relatively young cohort of 161 patients who underwent AF ablation (using standard pulmonary vein isolation techniques) in 2003-2004. At an average of five years of follow up, more than 80 percent were either AF-free or “clinically improved.”
Real-world impression: Although late recurrences of AF years after successful ablation have been reported, my impression (having started with AF ablation in 2004) is that most who are AF-free off drugs after one year have remained AF-free thus far.
2. Should AF ablation be offered as first-line therapy to younger patients?
Presently, the guidelines (circa 2006) for AF treatment recommend ablation as second-line therapy for those who have failed at least one trial of drug treatment. These “ancient” guidelines were conceived in an era when AF ablation was done laboriously and mostly in arrhythmia “institutes.” Times have changed, and it isn’t just one blogger’s opinion that AF ablation is getting easier.
In the good-news-for-AF-patients’ bucket goes this 1,500-patient Circulation publication from the University of Pennsylvania on the efficacy and risk of AF ablation in young patients. They analyzed AF-ablation results on the basis of age quartiles. Remarkably, all age groups had success rates in the 80 percent range, but the quartile of patients less than 45 years old also had no major complications — as in zero.
Incorporating the well known fact that young AF patients tolerate drug therapy poorly, these well-regarded researchers concluded that in the younger AF patient, ablation may be considered as a first-line option.
Real-world impression: This is a similar experience as ours. Since younger patients with AF frequently have low resting blood pressure and heart rate , they often do not tolerate the rate-slowing effects of most AF-drugs. Additionally, young patients tend to have smaller atria with less structural disease and more often than not, have focal drivers of AF. Less intrinsic atrial disease (like dilation of heart chambers) means less risk of procedural complications. More focality of AF “nests” means more chance of isolating the drivers with encircling RF lesions. These facts, in conjunction with the favorable long-term data from Hamburg, argue strongly that ablation should be considered a reasonable first-line option in young, otherwise healthy AF patients.
3. In patients with long-standing atrial fibrillation and congestive heart failure (CHF), how does AF ablation compare to amiodarone?
As background, it is well known that AF worsens outcomes in CHF. And this combination is common: AF and CHF are two of the most frequently cited in-patient cardiac diagnoses. It is also known that AF ablation is less successful in patients with long-term AF. So, in treating this common scenario (CHF and AF), there are two schools of thought in cardiology. As is often the case with emerging novel therapeutics, there are the old-schoolers, who in this example cling to the 1990s-vintage, once-daily amiodarone, and there are the new-agers, who believe catheter ablation deserves consideration.
Although one abstract does not unequivocally bury the rotary-phone guys, this amiodarone-versus-ablation study provides an early glimpse into the future. From the well-endowed “Italy-in-Texas” arrhythmia institute comes preliminary results of the AATAC trial. The trial randomized 105 patients with CHF, previously implanted ICDs and permanent or long-standing persistent AF to either amiodarone or AF ablation(s). (Having ICDs allowed researchers a window on true AF-suppression as ICDs have reliable AF-detection algorithms.) At only 10 months of follow-up, 75 percent of the ablation group (“after two ablation procedures”) versus 46 percent of amiodarone group were AF-free.
Real-world impression: Way back in 2004 in the New England Journal of Medicine (NEJM), it was shown that restoration and maintenance of sinus rhythm by catheter ablation in patients with CHF was beneficial — at least in Bordeaux. The question now, though, is whether AF ablation has progressed sufficiently to supplant drug therapy in advanced cases of AF and heart disease. AF ablation has come a long way in half a decade — it’s easier, but not easy. But neither is taking anti-arrhythmic drugs long term.
As for approaching AF with catheter ablation, I see us in a similar transition that we went through in the 1990s when ablation for SVT moved to first-line. Since ablating AF is much harder than SVT, the transition to non-drug therapy will be longer than it was with the one-burn-and-done SVT.
For sure, in climbing the AF-ablation mountain we are getting closer to the top, but there are still some steep pitches left.
JMM
*This blog post was originally published at Dr John M*
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