Discussion
The main finding of this study is the higher propensity of athletes
population of remaining free from AF recurrences after a single AF
ablation procedure compared with Non-athletes population, especially
when CTI ablation was associated with PVI. Furthermore, the majority of
our athletes population quickly resumed competitive sport activity.
Data from the literature suggest that freedom from AF is between 50-80%
in patients with either persistent or paroxysmal
AF5-10. However, there are few and conflicting
long-term data available in athletes and no difference in long-term
freedom from AF has been observed between athletes and NA.
In 2008 Furlanello et al. reported in a small population of 20 athletes
(mean age 44.4±13 years) 90% freedom from AF at 36.1±12.7 months after
PVI11. Another study including 182 subjects undergoing
PVI reported similar arrhythmia-free survival at one year in the lone AF
sport group versus controls (59% vs 48%, p=0.44), and similar rates of
procedure related complications (7.1% vs. 4.3%; p=0.45). The frequency
of redo PVI procedures was similar between the lone AF sport group and
controls (40.5% vs 37.3%, p=0.5)12. Koopman et al.
studied 94 endurance athletes and reported similar AF recurrence after
first PVI procedure13: both groups showed similar
arrhythmia free survival at 3 years (87 vs. 85%, p=0.88).
More recently, the case-control study by Decroocq et
al.14 showed the same AF recurrences rates at 1-year
follow-up after CA between 73 athletes and 73 matched sedentary
patients. After 5-year follow-up, AF recurrences rates did not differ
statistically between 38 (52%) athletes and 35 (47.9%) NA who
recurred. Finally, Mandsager et al.15 reported no
difference in arrhythmia recurrence between athletes and a matched
cohort of NA who underwent PVI. Single-procedure freedom from arrhythmia
was 75%, 68%, and 33% at 1 year for paroxysmal, persistent, and
long-standing persistent AF, respectively. Multiple-procedure freedom
from arrhythmia off antiarrhythmic drugs was 86%, 76% and 56% in
respective group at the end of follow-up (mean 1.4 ± 0.7 ablation per
athletes).
In our study, after a median follow-up of 787 days, 62.5% of athletes
were free from recurrences after one CA procedure and mostly without
antiarrhythmic drugs (87%), while after a redo procedure the overall
freedom from recurrences was 84%. However, in contrast with previous
data, our study showed a higher propensity of athletes of remaining free
from AF recurrences after a single AF ablation procedure compared with
NA population. After the first year of follow-up, athletes had, in fact,
a 48% reduced risk of recurrences than NA, especially in an age-related
analysis. Young athletes had a risk of AF recurrences 4 times lower than
young NA, while elderly athletes had a 46% reduced risk of AF
recurrences than elderly NA. These differences were not statistically
significant due to low sample size, but showed a positive trend in
athletes.
Different reasons may explain a better outcome of CA in athletes
compared to NA. First of all, athletes were slimmer than NA and the
correlation between BMI and AF is clearly
demonstrated16-18. Moreover, in NA LA volume was
significantly higher and persistent AF significantly more prevalent,
suggesting the presence of atrial remodelling and more advanced electric
LA disease. It has been demonstrated, in fact, that even small
difference in LA volume is an independent predictor of increased odds of
AF recurrence19. The negative trend showed in
endurance athletes may be correlated with atrial remodelling described
in this subpopulation of athletes20. Endurance
training leads to a harmonic enlargement of all four cardiac chambers as
an adaptation to exercise conditioning; however, the atrial walls are
significantly thinner than the ventricular walls and the higher stress
during episodes of training-related volume overload may contribute to
progressive LA enlargement and remodelling. Repetitive episodes of
atrial stretching and chronic inflammation secondary to excessive
endurance training may be contributing factors for atrial fibrosis and
AF, especially in aging athletes21,22.
Furthermore, in our study concomitant CTI ablation in athletes seemed to
be associated with an additional positive trend in terms of freedom from
recurrences, regardless previous documentation of typical AFL. AFL often
precedes or coexists with AF in athletes as a consequence of
exercise-induced enlargement of the atria23 and it may
also be life-threatening during exertion due to 1-to-1 conduction to the
ventricles under high sympathetic tone. Our results are in contrast with
available data from literature in NA population showing that
prophylactic CTI ablation irrespective of the previous documentation of
typical AFL is not associated with improvement in recurrence of atrial
arrhythmia compared with PVI alone. After the small randomized
controlled trial by Pontoppidan et al. in 200924, more
recently Mesquita et al.25 compared the outcomes of
patients without any previous documentation of typical AFL who underwent
PVI alone vs. PVI + prophylactic CTI ablation using a registry dataset
of more than 1900 consecutive patients who underwent a first AF CA. CTI
ablation remained unassociated with AF-free survival. The same results
were obtained by Lee et al. in 2019 in their retrospective study of 139
patients26 and they were confirmed also by the
meta-analysis by Romero et al. in 202027. Ongoing
randomized control trials in general population may give further
evidence to support or refuse prophylactic CTI ablation. Increased vagal
tone and structural atrial changes (i.e. fibrosis) associated with high
intensity sport practice may have a causative role in the development of
typical AFL in athletes and it may explain our results. However, further
data are requested. Recent recommendations for participation in
leisure-time physical activity and competitive sports suggest that in an
athlete presenting with AFL, there should be a very low threshold to
ablate the CTI, given the efficacy and safety of the procedure versus
the risk for recurrences during sports. European recommendations even
advice that CTI should be ablated prophylactically in athletes with AF
who want to engage in intensive exercise, especially when drug treatment
is considered or concomitantly with PVI28.
Lastly, the high success rate of AF CA obtained in our study confirmed
the possibility to permanently abolish AF in athletes, offering a unique
option for resume competitive sport. Most of our athletes were, in fact,
declared eligible to competitive sport activity after at least 3 months
from the CA as per Italian sport protocol.