An evaluation of 24 h Holter monitoring in patients with myotonic dystrophy type 1.

Aims: To evaluate the clinical effectiveness of routine 24 h Holter monitoring to screen for conduction disturbances and arrhythmias in patients with myotonic dystrophy type 1 (DM1).
Methods and Results: A retrospective two-centre study was conducted including DM1-affected individuals undergoing routine cardiac screening with at least one 24 h Holter monitoring between January 2010 and December 2020. For each individual, the following data were collected: Holter results, results of electrocardiograms (ECGs) performed at the same year as Holter monitoring, presence of cardiac complaints, and neuromuscular status. Holter findings were compared with the results of cardiac screening (ECG + history taking) performed at the same year. Cardiac conduction abnormalities and/or arrhythmias that would have remained undiagnosed based on history taking and ECG alone were considered de novo findings. A total 235 genetically confirmed DM1 patients were included. Abnormal Holter results were discovered in 126 (54%) patients after a mean follow-up of 64 ± 28 months in which an average of 3 ± 1 Holter recordings per patient was performed. Abnormalities upon Holter mainly consisted of conduction disorders (70%) such as atrioventricular (AV) block. Out of 126 patients with abnormal Holter findings, 74 (59%) patients had de novo Holter findings including second-degree AV block, atrial fibrillation/flutter and non-sustained ventricular tachycardia. Patient characteristics were unable to predict the occurrence of de novo Holter findings. In 39 out of 133 (29%) patients with normal ECGs upon yearly cardiac screening, abnormalities were found on Holter monitoring during follow-up.
Conclusion: Twenty-four hour Holter monitoring is of added value to routine cardiac screening for all DM1 patients.
Competing Interests: Conflict of interest: B.G.M.V.E. reports grants from Spieren voor Spieren, grants from Prinses Beatrix Spierfonds, grants from Dutch FSHD foundation, grants from Marigold foundation, grants from Netherlands Organisation for Scientific Research (NWO), grants from The Netherlands Organisation for Health Research and Development (ZonMw), grants from Association Francaise contre les Myopathies, grants and personal fees from Fulcrum, personal fees from Facio, personal fees from Arrowhead, all payed to the institution and outside the submitted work. C.G.F. reports grants from European Union’s Horizon 2020 research and innovation programme Marie Sklodowska-Curie grant for PAIN-Net, molecule-to-man pain network (grant no. 721841), grants from Grifols and Lamepro for a trial on IVIg in small fibre neuropathy, grants from Prinses Beatrix Spierfonds, Steering committtees/advisory board for studies in small fibre neuropathy of Biogen/Convergence, Vertex, Lilly and OliPass, outside the submitted work. K.V. reports grants from Medtronic, Abbott and Biotronik, and a consultancy agreement with Medtronic, outside the submitted work. All remaining authors have declared no conflicts of interest.
(© The Author(s) 2022. Published by Oxford University Press on behalf of the European Society of Cardiology.)