Age vs. ablation efficacy and risk

LONDON, ONTARIO, CANADA. Current US guidelines for the management of atrial fibrillation (AF) recommend that catheter ablation only be considered after antiarrhythmic therapy has failed. A group of researchers from London Health Sciences and the University of Pennsylvania now suggests that ablation should be considered as first-line therapy in patients younger than 45 years. This suggestion is based on the results of a major study comparing efficacy and complications in various age groups. The study included 1548 consecutive procedures over an 8-year period. The study participants were divided into four groups:

  • Group 1 – 232 patients below the age of 45 years (77% male) undergoing a total of 309 procedures (33% repeat rate)
  • Group 2 – 438 patients between the ages of 45 and 54 years (85% male) undergoing a total of 583 procedures (33% repeat rate)
  • Group 3 – 570 patients between the ages of 55 and 64 years (77% male) undergoing a total of 768 procedures (35% repeat rate)
  • Group 4 – 308 patients age 65 years or older (65% male) undergoing a total of 378 procedures (23% repeat rate).

As expected, members of group 1 were generally healthier than the older members of group 4 and were also more likely to be male (77% vs. 65%) and to have paroxysmal AF (71% vs. 63%). Group 1 members also had a smaller left atrium diameter (4.2 cm vs. 4.5 cm average), a lower CHADS2 score (0.3 vs. 1.1 average), as well as a lower incidence of hypertension (22% vs. 63%), diabetes (3.0% vs. 7.1%), and heart failure (2.2% vs. 9.4%).

All patients underwent an antral pulmonary vein isolation procedure guided by intracardiac echocardiography (Natale protocol) with elimination of non-pulmonary vein triggers as required. Isoproterenol infusions and burst pacing were used to document complete isolation. Patients with a history of right atrial flutter prior to or during the procedure also underwent a cavotricuspid isthmus ablation.

All participants were followed-up through clinical visits and trans-telephonic monitoring. Twenty-eight to 32 months after the last ablation close to 90% of the ablatees had achieved control of their AF as shown below:

Groups
Complete Success(1)
Partial Success(2)
Rare Episodes(3)
Failure
Group 1
76%
7%
4%
13%
Group 2
68%
11%
9%
12%
Group 3
65%
17%
6%
12%
Group 4
53%
23%
6%
18%

(1) no afib, no antiarrhythmics
(2) no afib, but only with the aid of (previously ineffective) antiarrhythmics
(3) 6 or fewer afib episodes during follow-up or a more than 95% reduction in afib burden compared to pre-ablation.

Major complications were defined as stroke/TIA, pulmonary vein stenosis (70% or more), tamponade, atrioesophageal fistula, phrenic nerve injury, retroperitoneal bleeding, and severe anaphylaxis. Other complications included large hematoma, femoral fistula or pseudoaneurysm, asymptomatic stenosis, and deep vein thrombosis. Complication rates were as follows:

Groups
Major
Other
Group 1
0%
0.6%
Group 2
1.7%
2.3%
Group 3
2.0%
2.9%
Group 4
2.6%
4.5%

The only variable affecting success rate was type of AF with persistent afibbers having a 64% greater risk of AF recurrence when compared to paroxysmal afibbers.

The authors point out that most young afibbers would be reluctant to take antiarrhythmics for decades and suggest that catheter ablation should be first-line therapy for afibbers below the age of 45 years as for this age group the outcome is very favorable and complications rare.

In an accompanying editorial, Drs. Hugh Calkins and David Edwards disagree with this conclusion and maintain that antiarrhythmic therapy should be considered first-line treatment in all age groups.

Leong-Sit, P, et al. Efficacy and risk of atrial fibrillation ablation before 45 years of age. Circulation: Arrhythmia and Electrophysiology, Vol. 3, October 2010, pp. 452-57
Edwards, DN and Calkins, H. Should catheter ablation of atrial fibrillation be a first-line therapy in the young? Circulation: Arrhythmia and Electrophysiology, Vol. 3, October 2010, pp. 425-27

Editor’s comment: The suggestion that catheter ablation should be first-line treatment for afibbers below the age of 45 years is well supported by the data presented in the report. However, there is still no data as to how permanent the effects of a successful ablation are. Is a successfully ablated afibber likely to still be in sinus rhythm 10 years after the procedure? Nobody knows! On the other hand, there is now evidence that antiarrhythmic therapy is less effective than ablation in most cases (52% vs. 77%)[1] and it is also well established that antiarrhythmics, especially amiodarone can have serious long-term adverse effects. Nevertheless, I personally would be reluctant to jump straight to an ablation, even at age 45 years, without having thoroughly explored other options such as those outlined in my 12-step plan.

The complete success rate for afibbers 65 years or older is clearly inferior to that observed for younger individuals (45 years or younger). However, members of the older group had several disadvantages when compared to the younger group:

  • Higher percentage of females (success rates for females are notoriously lower)
  • Higher percentage of persistent afibbers
  • Higher incidence of hypertension, diabetes and heart failure
  • Less use of repeat procedures.

Thus it is quite possible that success rates for older afibbers with paroxysmal AF and without comorbid conditions would be very close to that found for younger individuals if the use of repeat procedures was equal in the two groups.
[1] Calkins, H, et al. Treatment of atrial fibrillation with antiarrhythmic drugs or radiofrequency ablation: two systematic literature reviews and meta-analyses. Circulation: Arrhythmia and Electrophysiology, Vol. 2, 2009, pp. 349-61