Background-Intermittent rhythm monitoring (IRM) to detect atrial fibrillation (AF) recurrence is employed to evaluate the success of therapeutic interventions. In a large population of patients with continuous monitoring (CM), we investigated the sensitivity of various frequencies and durations of IRM strategies on the detection of AF recurrence, the dynamics behind AF recurrence detection, and we describe measures to evaluate temporal AF recurrence. Methods and Results-Rhythm histories of 647 patients (mean AF burden, 0.12±0.22; median, 0.014; 687 patient-years) with implantable CM devices were reconstructed and analyzed. With the use of computationally intensive simulation, the sensitivity of IRM of various frequencies and durations on the identification of AF recurrence was evaluated. Prolonged-duration IRM was superior to shorter IRM (P<0.0001). However, even with aggressive IRM strategies, AF recurrence was not detected in a great proportion of patients. The temporal AF burden aggregation (AF density) was directly related to IRM sensitivity (P<0.0001). Even at similar AF burdens, patients with high-density AF required higher-frequency or prolonged-duration IRM to achieve the same sensitivity as in low-density AF (P<0.0001). Patients with high-density, low-burden AF benefit the most from CM for detection of AF recurrence. Conclusions-IRM follow-up is significantly inferior to CM. IRM strategies will not identify AF recurrence in a great proportion of patients at risk. Temporal AF characteristics play a significant role in AF recurrence detection with the use of IRM. For the scientific, evidence-based evaluation of AF treatments, CM should be strongly recommended. Prospective studies are required to evaluate whether CM to guide clinical management can also improve patient outcomes. Clinical Trial Registration-URL: http://www.clinicaltrials. gov. Unique identifier: NCT00806689.