The feasibility of a Box isolation strategy for non-paroxysmal atrial fibrillation in elderly patients

Background: Catheter ablation of non-paroxysmal atrial fibrillation (non-PAF) is a therapeutic challenge especially in elderly patients. This study describes the feasibility of a posterior left atrium isolation as a substrate modification in addition to pulmonary vein isolation, the so-called Box isolation, for elderly patients with non-PAF. Methods: Two hundred twenty-nine consecutive patients who underwent Box isolations for drug refractory non-PAF were divided into two groups according to their age; younger group comprising 175 patients aged < 75 years and elderly group comprising 54 patients aged >= 75 years. Results: During 23.7 +/- 12.0 months of follow-up, the arrhythmia-free rates after one procedure were 53.1% in younger group versus 48.1% in elderly group (p = 0.50). Following the second procedure, all patients had electrical conduction recoveries along the initial Box lesion. However, a complete Box re isolation was highly established in both age groups (87.1% vs. 92.9%, respectively; p = 1.00). Recurrence of macro-reentrant atrial tachycardia was mainly associated with the gaps through the initial Box lesion in both age groups (25.8% vs. 21.4%, p=1.00), but typical cavo-tricuspid isthmus (CTI) dependent atrial flutter was significantly observed in the elderly patients' group only (all events were observed within 6 months after the initial procedure; 3.2% vs. 28.6%, p = 0.009). After two procedures, the arrhythmia-free rates increased to 73.1% in younger group versus 66.7% in elderly group (p = 0.38). The occurrence rate of procedural-related complications did not differ between the two age groups, and there were no life threatening complications even in elderly patients. Conclusions: Box isolation of non-PAF is effective and safe even in elderly patients. A prophylactic CTI ablation combined with Box isolation might be feasible to improve the long-term outcome. (C) 2016 Japanese Heart Rhythm Society. Published by Elsevier B.V.