Purpose: Patients undergoing cavotricuspid isthmus (CTI) ablation for typical flutter (AFL) have a high incidence of new onset atrial fibrillation (AF). We aimed to analyze the incidence and predictors for new onset AF in this subset of patients to stratify thromboembolic risk. Methods: Between 2016 and 2019, 70 patients without history of AF but with high-risk for developing AF, based on a recent AFL ablation or a high PACE score for AF risk, were prospectively included. All patients were monitored continuously by implantable loop recorder and followed by remote monitoring.Results: Overall 48 patients were included after CTI ablation and 22 patients were included based on a high PACE score. New onset AF rate at 12 months was significantly higher in the AFL group compared to PACE group (56.3% vs 22.7%, p=0.011). History of AFL was the only independent predictor for new onset AF (HR:3.82; 95% CI:1.46-10.03; p=0.006) at a median follow-up of 12 months (Q1-Q3:4-19 months). In the AFL group, two very strong independent predictors for new onset AF were a PACE score ³30 (HR:6.9; 95% CI:1.71-27.91; p=0.007) and HV interval ³55 (HR:11.86; 95% CI:2.57-54.8; p=0.002).Conclusions: AFL is the most important predictor for new onset AF. In patients undergoing AFL ablation, a high PACE score and/or long HV interval predict even higher risk, and may be useful in decision for empiric long-term anticoagulation.
