Background: Ablation for atrial fibrillation (AF) has emerged as an effective method of rhythm control. This exploratory analysis aimed to determine how various measures of recurrence would influence the definition of treatment success. Methods: Using an EHR dataset from 01/2007-06/2019 linked with Medtronic cardiac implantable electronic device (CIED) data, patients who underwent a first AF ablation procedure following CIED implantation were identified. Data were analyzed for recurrence of AF stratified by varying definitions of successful ablation. Performance of various simulated external AF monitoring strategies was assessed. Results: A total of 665 patients were analyzed including 248 with paroxysmal AF (mean age 66.2±9.3 years, 73.0% male) and 417 patients with persistent AF (mean age 67.3±9.0 years, 73.6% male). Patients with paroxysmal AF, survival free from recurrence at 1 year ranged from 28.2% to 72.1% (>6 min and >23 hours thresholds, respectively) with an overall median percentage of time in AF reduction of 99.6%. Patients with persistent AF, survival free from recurrence at 1 year ranged from 24.9% to 60.0% (>6 min and 7 consecutive days >23 hours thresholds, respectively) with an overall median percentage of time in AF reduction of 99.3%. A single 7-day monitoring strategy had a sensitivity of < 50% for detecting AF > 6 min in patients with paroxysmal and persistent AF. Conclusion: In this real-world dataset of AF patients with CIEDs undergoing catheter ablation, treatment success varied substantially with different definitions of minimally required AF duration and is significantly impacted by the method of recurrence detection.