br Methods br Results br Discussion The results of

Methods
Results
Discussion The results of this study demonstrate that (1) low-dose landiolol (0.5μgkg−1min−1) prevent heart rate elevation after AF ablation; (2) prophylactic administration of low-dose landiolol successfully prevented immediate AF recurrence within 3d after AF ablation without any adverse effects. RF ml calculator applications to the LA evoke an inflammatory response, which can cause subsequent AF recurrence shortly after AF ablation. Oral et al. performed PV isolation in 110 consecutive AF patients, and found that early AF recurrence occurred in 35% of patients at a mean of 3.7±3.5d after the procedure. The recurrence of AF was most frequently observed within 3d of the procedure in approximately 70% of cases [3]. The transient use of small amounts of corticosteroids, such as intravenous hydrocortisone the day of the procedure and oral prednisolone for 3d afterward, was reported to prevent immediate AF recurrences [16]. Recently, anti-inflammatory treatment by colchicine to reduce early recurrences after AF ablation was reported by Deftereos et al. [17]. These effects seem to be associated with decreased levels of inflammatory mediators, including body temperature, CRP, and interleukin-6 levels. Earlier reports demonstrated that relatively high-dose landiolol (2–5μgkg−1min−1) exerted an anti-inflammatory effect and could prevent AF after cardiac surgery [8,9]. Even though low-dose landiolol (0.5μgkg−1min−1) did not suppress CRP levels after AF ablation, AF recurrence was less frequent in the landiolol group. Landiolol may be superior to corticosteroids and colchicine for the prevention of immediate AF recurrence. Corticosteroids cause several side effects such as infections, rise in blood glucose level, and gastric ulcer. In particular, upper gastrointestinal side effects are a common risk in patients after AF ablation [18]. In addition, compared with oral anti-inflammatory drugs, landiolol is safer when side effects occur. Intravenously administered landiolol has an extremely short half-life (4min) compared with oral drugs. Cardiac sympathetic nerve over-activity is also associated with AF occurrence after cardiac surgery [19]. Sympathetic nerve disintegrity enhances automaticity or triggered activity, stimulating the fibrillation process, and shortens atrial refractoriness in a non-uniform fashion that favors AF perpetuation [19]. High washout rate of iodine-123-metaiodobenzylguanidine imaging and enhanced cardiac sympathetic tone were independently associated with AF recurrence after catheter ablation [6]. Landiolol suppresses the postprocedural heart rate and AF onset without lowering CRP levels, which suggests that controlling excessive sympathetic activity might be the most plausible reason for the effectiveness of landiolol in the present study. We administered a low-dose infusion of landiolol (0.5μgkg−1min−1) [15] at a rate lower than those described in other studies to minimize the incidence of side effects. Fujiwara et al. reported that infusion of landiolol (1.5–2.5μgkg−1min−1) for 2d after coronary artery bypass grafting had a preventive effect on the appearance of AF without suppressing cardiac function [10]. In a study published by Sezai et al., administration of landiolol at 2μgkg−1min−1 from the time of central anastomosis during coronary artery bypass grafting and for 2 subsequent days was associated with a lower incidence of AF [8]. Because RF catheter ablation is a relatively non-invasive procedure, low-dose landiolol may have been effective for preventing immediate AF recurrence. Interestingly, our subgroup analysis revealed that landiolol was more effective among patients not taking oral β-blockers compared to those taking oral β-blockers. Prophylactic low-dose landiolol therapy may be more suitable for patients not taking oral β-blockers. In addition, none of the patients developed hypotension or bradycardia, indicating the safety of low-dose landiolol administration after AF ablation.