ECG Predictors for New-Onset Atrial Fibrillation Within a Year After Radiofrequency Ablation of Counterclockwise-Rotating Atrial Flutter.

New-onset atrial fibrillation (AF) after ablation of typical atrial flutter (AFL) is not rare. This study aimed to investigate the predictive value of electrocardiographic parameters on new-onset AF post-typical AFL ablation. A total of 158 consecutive patients (79.1% males, mean age 57.8 ± 14.3 years) with typical AFL were enrolled between January 2012 and August 2017 in this single-center study. Patients with a history of AF before ablation were excluded. ECGs during sinus rhythm (SR) and AFL were collected. The duration of the negative component of flutter wave in lead II (D), proportion of the D of the total circle length of AFL (D%), amplitude of the negative component of flutter wave in lead II (A), duration (D), and amplitude (A) of negative component of the P wave in lead V1, and P wave duration in lead II (D) during sinus rhythm were measured. During a median follow-up of 26.9 ± 11.8 months, 22 cases (13.9%) developed new-onset AF. D was significantly longer in patients with new-onset AF compared to patients without AF (114.7 ± 29.6 ms vs. 82.7 ± 12.8 ms, < 0.0001). A was significantly lower (0.118 ± 0.034 mV vs. 0.168 ± 0.051 mV, < 0.0001), D (144.21 ± 23.77 ms vs. 111.46 ± 14.19 ms, < 0.0001), and D was significantly longer (81.07 ± 16.87 ms vs. 59.86 ± 14.42 ms, < 0.0001) in patients with new-onset AF. In the multivariate analysis, D [odds ratio (OR), 1.428; 95% CI, 1.039-1.962; = 0.028] and D (OR, 1.429; 95% CI, 1.046-1.953; = 0.025) were found to be independently associated with new-onset AF after typical AFL ablation. Parameters representing left atrial activation time under both the SR and AFL were independently associated with new-onset AF post-typical AFL ablation and may be useful in risk prediction, which needs to be confirmed by further prospective studies.