Nice, France - Minimally invasive surgical ablation of atrial fibrillation (AF), also known as epicardial ablation, is emerging as a viable alternative to conventional catheter ablation of AF in certain niche patient populations. At Cardiostim 2008 here last month, experts discussed the early experience with epicardial ablation and the importance of electrophysiologists and surgeons working side by side on this.

As cardiothoracic surgeon Dr Vigneshwar Kasirajan (Medical College of Virginia, Richmond) explained: "We are doing more cath ablations, but some people are not good candidates for this—for example, obese patients in whom we see poor fluoroscopic imaging with catheter ablation and a high risk of vascular complications."

Another niche area for epicardial ablation could be nonparoxysmal, persistent (chronic) AF, he noted, which still has a high recurrence rate when treated with radiofrequency catheter ablation. Other possible candidates include the very elderly, those at high embolic risk, those with scar tissue from previous cardiac surgery, and those with reduced ejection fraction.

Minimally invasive surgical approaches to treat AF use small incisions of just 2 to 3 cm between the ribs—which don't need to be spread—and are performed on the beating heart and so do not require bypass; the average length of hospital stay is only three days. And in some institutions, surgeons are adopting an entirely thoracoscopic approach, which further reduces the procedure time and length of hospital stay required.

The surgeon places a bipolar clamp on the left atrium near the pulmonary veins, and ablation is performed using radiofrequency, much like a catheter ablation. In addition, the ganglionic plexuses are usually ablated, and the ligament of Marshall is often disconnected (this is a vestige of a vein that was required during fetal development but is no longer needed) and the left atrial appendage amputated. The latter is thought to be the area in which most clots form, thereby potentially reducing the long-term likelihood of stroke even if AF were to return.

In many institutions, the surgeon and the electrophysiologist work closely together, with the latter monitoring mapping to ensure that the ablation is complete and that the overactive nerves are no longer a problem.

At Cardiostim, Kasirajan said epicardial ablation "is a significant step forward for many patients who would not be offered anything else," such as the elderly, and he noted that it was important "to focus on the difficult-to-treat patients."

He reported his team's experience with 46 patients and explained that although there have been blips—for example, "we dramatically increased our success rate after we started to dissect the fat off the atrium, starting in June 2007"—two-year follow-up now shows a success rate of almost 80% (although this included some patients who underwent additional procedures). "They do have a lot of AF immediately after the operation but then it disappears," he noted.

This is feasible and safe for experienced surgeons, and the results are quite good.

A recently published literature review of the experience has also shown reasonable results [1], he noted, with success rates of 83.7% in patients with paroxysmal AF and 56.5% in those with persistent/long-standing AF.

Meanwhile, Dutch surgeon Dr Wim Jan van Boven (St Antonius Hospital, Nieuwegein, the Netherlands) reported his center's experience with a totally thoracoscopic approach, which takes around one to one and a half hours compared with the three to four hours needed for the minimally surgical approach, he said.

His center treated 38 patients with the thoracoscopic approach between 2005 and 2006, with an overall success rate of 78% and an average in-hospital stay of just 1.5 days, he noted.

"This is feasible and safe for experienced surgeons, and the results are quite good even in those with prior cath ablation," he noted.

Electrophysiologist Dr Warren Jackman (University of Oklahoma Health Sciences Center, Oklahoma City) spoke at Cardiostim of the importance of the electrophysiologist and surgeon working together to perform epicardial ablation. Afterward, he told heartwire: "My perception is that both of these procedures [epicardial and catheter] ablation are evolving, and we are going to learn that the minimally invasive surgical approach is good for certain groups and that catheter ablation is good for others."

Jackman feels that epicardial ablation holds most promise for long-standing persistent AF, something that "often requires multiple procedures and has proven difficult to treat with catheter ablation. I think this patient population is going to turn out to have the best overall results for one-procedure success [with epicardial ablation]."

Expanding upon his reasoning, he said that with catheter ablation, "we can make a series of points next to the line of ablation, and we can make the line and test it, but it may be blocked because that muscle is stunned but not killed, and then [AF] may recur. It's also hard to get to some areas to perfectly complete the line with a catheter.

"Surgically, you are going to be a little more selective in the lines you make because your access is going to be limited, but where you do have access you can create an area of full-thickness damage all the more easily." So "with epicardial ablation you can be more assured, with proper testing, that you can make ablation lines in the left atrium that are going to be permanently blocked," he explains.

And Jackman said he could not stress enough how important it is for the electrophysiologist and surgeon to work together to maximize the chances of success: "The results will be better if you have an electrophysiologist to perform mapping at the start and the end of the procedure to confirm that the line has been successfully ablated. Mapping is becoming key."