Mechanism, underlying substrate and predictors of atrial tachycardia following atrial fibrillation ablation using the second-generation cryoballoon.

BACKGROUND: Data regarding atrial tachycardia (AT) following second-generation cryoballoon ablation (CBA) of atrial fibrillation (AF) are limited.

AIM: To describe the incidence, mechanisms, and clinical predictors of ATs following CBA.

METHODS AND RESULTS: In this retrospective single-center study 238 patients undergoing CBA for treatment of paroxysmal (91/238; 38.2%) or persistent AF were analyzed. During a mean follow-up of 11.9 ± 5.5 months recurrence of AF occurred in 49/238 patients (20.6%) and AT in 27/238 (11.3%). Twenty-six patients with AT and 14 with AF only underwent a redo ablation. The prevailing mechanism of AT was macroreentry [typical atrial flutter (AFL) (n = 10), left atrial macroreentry (n = 14), focal left-AT (n = 2)]. Non-cavotricuspid-isthmus-dependent macroreentry right-AT was mapped and ablated in 3 patients after initial AFL ablation. In a multivariate regression model, persistent type of AF (HR = 3.3; CI = 1.2-9.4), cardiomyopathy (HR = 3.5; CI = 1.5-8.4), treatment with beta-blockers (HR = 0.3; CI = 0.1-0.6), and pulmonary vein-abnormality (HR = 4.6; CI = 2.1-10.4) were independent predictors of AT. Substrate analysis revealed a significantly higher number of low voltage areas in the left atrium in patients with left-AT in comparison to patients with AF recurrence only (2.0; IQR=2.0-4.0 vs. 0.5; IQR = 0.0-2.25; p = 0.005).

CONCLUSION: In this study, AT after CBA occurred in 11.3% of patients with macroreentry being the prevalent mechanism. All patients with left-AT presented with low voltage areas in the left atrium, suggesting a more progressive underlying fibrotic disease in these patients.