Study patients
This single-center retrospective study included consecutive patients with non-paroxysmal AF who underwent cryoballoon ablation with PVI between January 2016 and December 2018. Patients who underwent heart surgery were excluded because the surgery could have contributed to the AT occurrence. Patients who underwent LA roof-line ablation using a radiofrequency (RF) catheter were also excluded because the effect of the ablation was considered to vary between LA roof-line ablation performed with a cryoballoon and that performed with an RF catheter. Patients who did not undergo clinical follow-up of more than 3 months were excluded from the analysis. We hypothesized that LA posterior wall (LAPW) ablation, including cryoballoon ablation of the LA roof in addition to PVI, is effective in reducing the recurrence of persistent AF in patients with non-paroxysmal AF without inducing AT. To compare the effect of additional LAPW ablation with that of only PVI, only patients who did not undergo MI ablation were analyzed; those who underwent only LA roof-line ablation without LAPW bottom line ablation were excluded. All patients underwent three-dimensional computed tomography and transthoracic echocardiography before ablation. Paroxysmal AF was defined as AF terminating within 7 days according to the previously reported definition5; hence, non-paroxysmal AF was defined as AF persisting for more than 7 days. Baseline demographic characteristics, comorbidities, and medications were recorded. Written informed consent was obtained from all patients prior to the ablation procedure. This study was approved by our local ethics committees and conform to the guiding principles of the Declaration of Helsinki.