Atrial Fibrillation Management at HR 2010 June 23, 2010

I had an absolutely amazing experience at the Heart Rhythm Society’s 31^st Annual Scientific Sessions last month in Denver, Colorado. It seems that this meeting just continues to get better each year. This time, there were many new and provocative studies presented on atrial fibrillation (AF) management. Over the next few posts, I would like to share some of the studies that I think are most impactful.

First, I will provide results on two studies¹ that my team presented. These studies involved nearly 40,000 patients and addressed the long term outcomes of AF ablation within an entire healthcare system. It was certainly interesting to see the news outlets from around the world cover them, including Heartwire, Tehran Times, Ethiopian Review, and The Times of India. While it was great to have this kind of media attention after all of the hours of work that went into the studies, it was also very humbling to receive a few negative posts from the online versions of these papers.

By way of background, it is well known that AF is an important cause of premature death, strokes, heart failure, and dementia. A recently published observational study showed that AF appears to double the risk of Alzheimer’s disease. Although the mechanism is unknown, AF could potentially promote amyloid plaque formation in susceptible patients from hemodynamic alterations, through activation of systemic inflammation pathways (both AF and Alzheimer’s disease have been associated with elevated CRP levels), or even through micro emboli that cannot yet be imaged with current CT/MRI cranial imaging. It is also interesting to note that patients with both AF and Alzheimer’s disease have a particularly aggressive course resulting in rapid cognitive decline and premature death in comparison to Alzheimer’s disease patients without AF.²

In our two studies, my team evaluated 4,212 patients who have undergone an AF ablation procedure at one of the five hospitals within the Intermountain Healthcare System that perform the procedure. We included every patient at Intermountain Healthcare who has ever had this procedure. We then compared the three year outcomes of these AF patients with nearly 17,000 AF patients who were matched for age and gender at Intermountain Healthcare who remained on medical therapy for their AF. For a second control group, we looked at nearly 17,000 patients without AF (matched for age and gender) at Intermountain Healthcare.

The mean age of all three groups was 65. While atrial fibrillation patients were less likely to have diabetes, they were more likely to have hypertension, heart failure, or valvular heart disease than those patients who did not undergo ablation. 

Overall, 64% of all ablation patients were “cured” from their AF at three years (no recurrences and off of all anti-arrhythmic medications). We have not yet fully analyzed the AF burden in the 36% of the patients that did not get a complete “cure” but it appears that in these “unsuccessful ablations,” the AF burden had been reduced significantly.

Interestingly, catheter ablation of AF eliminated the increased risk of premature death, stroke, dementia, and Alzheimer’s disease compared to AF patients who remained, on what their individual physicians felt, was the best medical therapy. The study results are especially impactful because they have shown, in a large healthcare system, that patients who undergo AF ablation procedures have extremely favorable long-term clinical outcomes.

Certainly, there are many limitations to this observational study. One could argue that the medically treated patients did not receive the best medical therapy. However, Intermountain Healthcare consistently receives very high scores for providing patients with the best evidence-based medicine. Also, because our study included every AF ablation patient at Intermountain Healthcare, it also meant that it included very low volume ablation physicians. Referral bias certainly could have played a role. Patients who received ablation therapy had very symptomatic AF refractory to anti-arrhythmic drug therapy. In contrast, the medically treated patients were primarily minimally symptomatic or asymptomatic from their AF.

While we all await the long-term clinical outcomes of AF ablation from the prospective multi-center randomized controlled CABANA clinical trial, these studies represent some of the best data currently available that a potentially curative approach to AF management with catheter ablation may offer a potentially superior outcome to medical therapy.

1. Day, John, et al. Catheter ablation of atrial fibrillation reduces the risk of Alzheimer’s disease and dementia. Heart Rhythm Society 2010 Scientific Sessions; May 13, 2010; Denver, CO and Day, John, et al. Atrial fibrillation significantly reduces long-term mortality and strokes in a large patient population. Heart Rhythm Society 2010 Scientific Sessions, May 14, 2010;  Denver, CO.
2. Bunch, Jared T., Atrial fibrillation is independently associated with senile, vascular, and Alzheimer’s dementia. Heart Rhythm 2010;7:433-437