Which patients recur as atrial tachycardia rather than atrial fibrillation after catheter ablation of atrial fibrillation?

Introduction: The ablation gaps have been known as the main mechanism of recurrence as atrial tachycardia (AT) rather than atrial fibrillation (AF) after AF catheter ablation. However, AF organization due to reduction of critical mass or focal trigger may also be the mechanism of AT recurrence. We sought to find out the main clinical factors of recurrence as AT rather than AF after AF ablation in the absence of antiarrhythmic drug effect. Methods: We analyzed 521 patients (70.8% men, 64.1% paroxysmal AF) who experienced AT or AF recurrence without antiarrhythmic drug effect during 44.7 ± 25.4 months follow-up. Results: Among 521 patients with recurrence, 42.0% (219 of 521) recurred with AT. The proportion of AT recurrence was not different between the pulmonary vein isolation only group and additional linear ablation group (45.1% vs. 38.1%, p = 0.128). The absence of hypertension (odds ratio [OR] 0.49, 95% confidence interval [CI] 0.29–0.83, p = 0.007), small left atrial (LA) volume index (OR 0.89 per 10 mL/m², 95% CI 0.79–1.00, p = 0.049), and high mean LA bipolar voltage (OR 2.03 per 1 mV, 95% CI 1.30–3.16, p = 0.002) were independently associated with AT recurrence, whereas additional linear ablation was not. Among 90 patients who underwent repeat ablation procedure, rates of PV reconnection (p = 0.358) and gap in prior linear ablations (p = 0.269) were not significantly different between AT recurrence group and AF recurrence group. Conclusion: The degree of LA remodeling is significantly associated with recurrence as AT after AF ablation, irrespective of potential ablation gap in linear lesion.