Appropriate timing of electrophysiological study in myotonic dystrophy type 1: unsolved question—Authors’ reply

We thank Russo and Wahbi for their important comment.1 To be highly succinct, the 2021 ESC guidelines on cardiac pacing2 mention in the respective table only the indications for permanent pacing in patients with neuromuscular disease that are beyond general pacemaker indications. The table refers to neuromuscular disease in general, with myotonic dystrophy (MD) in particular. The guidelines clarify that any infrahisian atrioventricular (AV) conduction defect such as AV block second- or third-degree represents a class I indication for permanent pacing, even first-degree AV block, as long as it can be demonstrated that there is an infrahisian component. The reason for this is firstly that in many neuromuscular diseases there is an increased risk of very rapid progression to complete heart block without escape rhythm posing a vital risk to the patient, namely bradyarrhythmic sudden cardiac death. Secondly, complete heart block is in some neuromuscular diseases such as...