Extended period rhythm outcomes of posterior box isolation of left atrium during pan-spectrum of atrial fibrillation catheter ablation in 4 randomized clinical trials

Abstract Background Catheter-based electrical posterior box isolation (POBI) in addition to circumferential pulmonary vein isolation (CPVI) did not improve rhythm outcome of atrial fibrillation (AF) catheter ablations (AFCA). We analyzed the long-term rhythm outcomes of previously conducted our 4 randomized controlled trials (RCTs) comparing CPVI vs. additional POBI by intention to treat. Methods We analyzed 575 AF patients who were included in 4 RCTs (PAF [paroxysmal AF], PEACEFUL [persistent to paroxysmal AF]; POBI [persistent and long-standing persistent AF]; and RILI [repeat procedures] trials) comparing the usefulness of additional POBI after further long-term protocol-based rhythm follow-up. We compared the primary endpoint as clinical recurrence after index procedure and major adverse cardiac event, and the secondary endpoint as procedure time, procedure-related complication rate, recurrence as atrial tachycardia (AT), and cardioversion or repeat procedure rates. We also conducted Cox regression analysis to evaluate the efficacy of POBI. Results After a median follow-up of 48months, there was no significant difference in the clinical recurrence (42.9% vs. 41.3%; log-rank P=0.855) and major adverse cardiac event (4.5% vs. 3.7%; log-rank P=0.675). Procedure time was significantly longer (p=0.003) and AT recurrence rate was higher (6.6% vs. 12.6%; log-rank P=0.014) in the additional POBI group. In patients who experienced clinical recurrence, there were no significant differences in the rates of cardioversion (33.9% vs. 46.6%, P=0.059) or the need for a repeat procedure (30.4% vs. 31.7%, P=0.955) between the two groups. Catheter-based POBI did not improve AFCA outcomes (HR 1.07 [0.81~1.40], P=0.655), regardless of paroxysmal, persistent to paroxysmal, persistent AFs, or the 2nd procedures. In the redo mapping after RCTs (n=64), PV reconnection rate did not differ, but reentrant AT was more common in POBI than in CPVI alone group (46.7% vs. 10.7%, P=0.007), while extra-PV trigger was more common in CPVI alone than in POBI group (29% vs. 3.0%, P=0.012). Conclusions Additional-POBI to CPVI did not improve long-term rhythm outcomes. Additional-POBI to CPVI is related to the increase of AT recurrence and the decrease of extra-PV trigger.