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.