Focal right atrial tachycardia with three foci in a patient with polymyositis.

Cardiac involvement secondary to polymyositis is not infrequent. In addition, it sometimes presents various forms of arrhythmia, including atrial tachycardia (AT). A 72-year-old female who had 5-years history of polymyositis was referred to our clinic with symptomatic supraventricular tachycardia with 2:1 atrioventricular conduction. Electrophysiological study revealed a total of three focal AT in right atrium with the origin of the basal right atrial appendage (AT1), coronary sinus ostium (AT2), and low lateral right atrium (AT3), respectively. Endocardial bipolar voltage mapping showed low voltage area in the limited area, partially overlapping with the focus of AT3. We finally terminated AT2 targeting an early fractionated potential and AT3 at early activation site with a support of flexibly-bended deflectable sheath while accidentally eliminating AT3 with the bumping of a catheter. With the additional applications, we completely eliminated all AT. AT were never provoked by any inductions with isoproterenol infusion. <Learning objective: Polymyositis is a broad-spectrum inflammatory disease which could involve myocardium, sometimes leading to the arrhythmogenicity. We should recognize the possibility of arrhythmia occurrence with multiple foci in patients with polymyositis when performing catheter ablation even if there were no obvious structural and functional heart abnormality.>.