Aims Radiofrequency ablation (RFA) is frequently used to treat sustained arrhythmias. One major complication is pericardial effusion-tamponade. Therefore, many centres perform echocardiography after interventions, but data on necessity of such routine procedures are scarce. Methods and results We included 510 patients with RFA and compared echocardiographic results acquired before and ,24 h after intervention. We defined pericardial effusion as 'small', if ,10 mm in diastole, 'moderate' if .10

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... m, 'large' if .20 mm, or tamponade (.20 mm with haemodynamic compromise). Age was 55 + 16 years, 40% were females. Thirty-five percentage underwent RFA for atrioventricular nodal re-entrant tachycardia (AVNRT), 28% for atrial flutter, 15% for atrial fibrillation (AF), 12% for Wolff-Parkinson-White (WPW) syndrome, and 10% for different other arrhythmias. In 16 patients (3.2%), small asymptomatic effusions were detected. The only moderate effusion was suspected due to procedure circumstances. Radiofrequency ablation for AF had a higher incidence compared to AVNRT and flutter (P ¼ 0.001 and ,0.0001, respectively) or to WPW syndrome (P ¼ 0.06). Conclusion Numbers of significant pericardial effusion as detected by routine echocardiography were low (3.6%) and clinically relevant effusions absent. We thus recommend performing echocardiography after RFA only, if effusion is suspected clinically or if RFA was performed for AF, due to the high incidence of effusions with this type of ablation. ---