Discussion
Given the rising proportion of elderly patients with AF, the utilization
of CA in elderly patients is growing. Numerous studies have investigated
the outcomes of CA of AF in elderly patients, and the mean age of the
included patients is variable4-13. To the best of our
knowledge, ours is the first study from the US to compare the outcomes
of CB vs. RF AF ablation in elderly patients. The main findings of our
study are: (1) The safety and efficacy of index CB vs. RF AF ablation in
the elderly patients are similar; (2) LA diameter is an independent
predictor of arrhythmia recurrence after AF ablation in the elderly
patients, regardless of index ablation modality.
Our findings are in line with the previous studies from Asia, which also
reported comparable safety and efficacy of CB vs. RF ablation of AF in
elderly patients4,5.
The mean age of included patients was 78 years in these studies, similar
to our study. However, our success rate at one year follow up are lower
as compared to the previous studies. This may be due to a greater
proportion of PsAF patients and higher average LA diameter in our
cohort, as these factors have been reported to be associated with lower
success rate of an ablation
procedure4,14,15.
We also demonstrated that higher LA diameter is an independent predictor
of arrhythmia recurrence in elderly patients after CA of AF. This
finding consolidates the evidence of the pathologic role of dilated LA
in initiation and maintenance of AF in elderly patients and suggests
that dilated LA has independent poor prognostic value regardless of the
ablation modality and presence of other comorbidities such as OSA and
PsAF, which contributes to arrhythmia recurrence.
Our complication rates are lower in comparison to the rate reported in
previous
studies4,5.
Transient phrenic nerve palsy (PNP) has been reported to be the most
commonly associated complication with CB ablation16,17.
Ikenouchi et al., in their study of patients >75 years old,
reported transient PNP as the most common complication following CB
ablation5. However, we
did not observe any incidence of PNP in our study. This could be due to
effective phrenic nerve monitoring; however, it could also reflect the
small size of the CB cohort in our study. We also observed a lower
incidence of cardiac tamponade as compared to previous studies. Over-all
the safety data from our small study suggest that CA of AF is a
relatively safe procedure in patients > 75 years old with
appropriate patient selection.
Our study has several limitations, including those inherent to a
single-center, non-randomized, retrospective study with a small sample
size. The choice of ablation technique was left to the discretion of the
operator. In addition, only patients enrolled after 2014 were treated
with contact force sensing catheters, which are associated with an
improved success rate. This could have introduced some bias. Finally,
the lack of continuous ECG monitoring after ablation could have resulted
in underestimation of arrhythmia recurrence.
In conclusion, based on our study, the safety and efficacy of index CB
vs. RF AF ablation in patients > 75 years of age is
comparable, and LA diameter is a significant predictor of arrhythmia
recurrence independent of index ablation modality. Further prospective
randomized studies are required to confirm our findings.