Arrhythmia Detection after Atrial Fibrillation Ablation: Value of Incremental Monitoring Time ANTON A.W. MULDER, M.D., MAURITS C.E.F. WIJFFELS, M.D., PH.D., ERIC F.D. WEVER, M.D., PH.D., JOHANNES C. KELDER, M.D., and LUCAS V.A. BOERSMA, M.D., PH.D. From the Department of Cardiology, St. Antonius Hospital, Nieuwegein, The Netherlands Background: After pulmonary vein isolation (PVI), patients need to be followed to analyze the effect of the treatment. We evaluated the influence of the duration of Holter monitoring on the detection of arrhythmia recurrences after a single PVI at 12 months. Methods: Consecutive patients with paroxysmal atrial fibrillation (AF) underwent successful PVI with phased radiofrequency and pulmonary vein ablation catheter. Follow-up was performed with electrocardiogram at 3, 6, and 12 months and 7-day Holter at 12 months. Symptomatic patients received additional event recording. The 7-day Holters at 12 months were evaluated for documented left atrial tachyarrhythmia recurrences, and each individual day with AF was categorized. Results: At 12 months after the procedure, 21 of the 96 (22%) patients had AF on their 7-day Holter. In the patients with AF recurrence, there was an increase in sensitivity from 53% of a 1-day Holter up to 88% with 4-day Holter, and 100% of a 7-day Holter. Monitoring with duration of less than 4 days resulted in significantly less detection of patients with AF compared to 7-day Holter. Conclusions: A 4-day Holter at 12 months has an 88% sensitivity for arrhythmia detection, and appears to provide a sufficient monitoring time. Prolonging the monitoring time to 7 days does not significantly increase the yield. (PACE 2012; 35:164–169) Holter, atrial fibrillation, catheter ablation, pulmonary vein isolation Introduction After ablation of the pulmonary veins (PVs) for atrial fibrillation (AF), patients need to be followed to assess the effect of the treatment. In the consensus statement of 2007, it was recommended to perform a 24-hour Holter monitoring between 3- and 6-month intervals after ablation for 1–2 years following ablation. 1 However, relying only on such short duration of monitoring may overestimate the number of patients truly free from AF after ablation. Adding traditional 12- lead electrocardiogram (ECG) or event recording, especially in symptomatic patients, may increase AF detection but will still miss asymptomatic episodes. Alternatively, continuous monitoring with implantable loop recorder, transtelephonic monitoring, or multiday Holter monitoring may be performed. Such extended monitoring strategies, however, are expensive, invasive, or uncom- Disclosures: Dr. Boersma is a consultant for Medtronic and a prior stockholder of Ablation Frontiers. The Cardiology Department has received grant support for research from Ablation Frontiers, Inc. Drs. Wijffels, Wever, Kelder, and Mulder have no conflict of interest. Address for reprints: Anton A.W. Mulder, M.D., Cardiology Department, St. Antonius Hospital, PO Box 2500, 3430 EM, Nieuwegein, The Netherlands. Fax: 31-30-6092274; e-mail: a.mulder@antoniusziekenhuis.nl Received April 13, 2011; revised June 6, 2011; accepted July 10, 2011. doi: 10.1111/j.1540-8159.2011.03202.x fortable. The main question arises, how much monitoring is really needed to be able to determine freedom of AF, and whether this is acceptable to health care providers and patients. In a prior study on the efficacy of PV isolation (PVI) with single- tip catheter ablation, it was concluded that Holter monitoring with a duration of less than 4 days significantly underestimated the number of AF recurrences. 2 In the present article, we reevaluated the influence of the duration of Holter monitoring on the detection of arrhythmia recurrences after a single PVI with PV ablation catheter (PVAC)- phased radiofrequency (RF), and explore new concepts to evaluate the diagnostic yield Holter durations. Methods Patients The subjects of this study were patients with symptomatic paroxysmal AF (PAF). PAF was defined as recurrent AF (two or more episodes) that terminates spontaneously within 7 days. 1 Ninety-six consecutive patients were treated at the St. Antonius Hospital, Nieuwegein, The Netherlands. All patients were treated with the PVAC, a ring-shaped multielectrode ablation catheter using alternating unipolar- and bipolar- phased RF energy. 3 All patients who underwent a 7-day Holter at 12 months after a single PVI between April 2007 and December 2008 were included in the study. The St. Antonius Hospital Ethics Committee review board gave approval for C 2011, The Authors. Journal compilation C 2012 Wiley Periodicals, Inc. 164 February 2012 PACE, Vol. 35