LAUSR

Circulation. 2020;141:e94. DOI: 10.1161/CIRCULATIONAHA.119.044066 Hiroshi Sugimoto, MD Yayoi Taniguchi, MD, PhD To the Editor: Lüker et al1 conducted the first randomized trial that compared external and internal cardioversion of atrial arrhythmias in patients with implantable cardioverter-defibrillators. They found that external cardioversion was more effective and noninferior to internal cardioversion in terms of safety. In addition, they made a valuable discovery that internal cardioversion could reveal silent lead malfunction. We read the results with great interest but came up with the following 2 concerns. First, the incidence of silent lead malfunction, 2.7% in their study, was higher than our clinical impression. We assume that silent lead malfunction is caused by the specific type of lead. Furthermore, we think that previous external shock can be the cause of silent lead malfunction. However, the authors did not mention such information in the article. Second, the authors concluded that external cardioversion was more effective than internal cardioversion (93% versus 65%). We think such a conclusion can be misleading because they compared the conversion rates obtained after single or multiple external cardioversion and the conversion rates obtained after single internal cardioversion. Although the study design was clinical, when it comes to the efficacy, comparison should be based on conversion rates obtained after single cardioversion. We appreciate the authors’ great efforts, although we are concerned about the lack of important information and misleading results as mentioned above.