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Arrhythmia Management in Myotonic Dystrophy Type 1

Arrhythmia Management in Myotonic Dystrophy Type 1 To the Editor: Dr Wahbi and colleagues1 concluded that sudden death mortality was improved in patients with myotonic dystrophy type 1 (DM1) and moderate conduction abnormalities on electrocardiogram who underwent an invasive strategy consisting of an electrophysiological study followed by prophylactic pacing if the HV interval exceeded 70 milliseconds. In our opinion, there are uncertainties in how the retrospective observational trial was conducted and reported that limit the ability to determine if their invasive strategy was associated with a survival advantage. It is not clear how patients were selected for the invasive strategy group or for the noninvasive strategy comparison group. The authors excluded patients receiving pacing devices based on electrocardiogram criteria alone who should have been included in the noninvasive strategy group. None of the 145 noninvasive strategy patients received a pacing device during follow-up. Conduction disease is progressive in DM1 and it would be atypical that none of the patients would have developed severe electrocardiogram abnormalities or bradycardia for which implantation of an antiarrhythmia device would have been prudent.2 It seems as if the noninvasive strategy group was merely observed rather than treated for arrhythmia risk and therefore does not form an appropriate comparison cohort despite the propensity score risk adjustment. Procedures requiring anesthesia, including the electrophysiological study, are not low risk in patients with DM1.3 Based on the forced vital capacity data, many of the patients had severe respiratory muscle involvement. The authors did not report procedural complications such as unplanned intubation or respiratory failure requiring prolonged hospital stay. The authors downplayed the fact that conduction disease in patients with DM1 is not only associated with a risk for complete heart block but also with a risk for ventricular tachyarrhythmias.4 It is not evident why only 14 patients received implantable cardioverter-defibrillators (ICDs) when 26 patients had inducible sustained ventricular tachyarrhythmias on the electrophysiological study. In nearly half of the pacemaker patients who died suddenly, ventricular fibrillation was the observed rhythm, raising the question of whether the ICD would be a more appropriate antiarrhythmia device in many patients with DM1. Back to top Article Information Conflict of Interest Disclosures: The authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Dr Groh reported receiving grants from the Muscular Dystrophy Association. Dr Bhakta reported no disclosures. References 1. Wahbi K, Meune C, Porcher R, et al. Electrophysiological study with prophylactic pacing and survival in adults with myotonic dystrophy and conduction system disease. JAMA. 2012;307(12):1292-130122453570PubMedGoogle ScholarCrossref 2. Bhakta D, Shen C, Kron J, Epstein AE, Pascuzzi RM, Groh WJ. Pacemaker and implantable cardioverter-defibrillator use in a US myotonic dystrophy type 1 population. J Cardiovasc Electrophysiol. 2011;22(12):1369-137522035077PubMedGoogle ScholarCrossref 3. Mathieu J, Allard P, Gobeil G, Girard M, De Braekeleer M, Bégin P. Anesthetic and surgical complications in 219 cases of myotonic dystrophy. Neurology. 1997;49(6):1646-16509409361PubMedGoogle ScholarCrossref 4. Merino JL, Carmona JR, Fernández-Lozano I, Peinado R, Basterra N, Sobrino JA. Mechanisms of sustained ventricular tachycardia in myotonic dystrophy: implications for catheter ablation. Circulation. 1998;98(6):541-5469714111PubMedGoogle ScholarCrossref http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png JAMA American Medical Association

Arrhythmia Management in Myotonic Dystrophy Type 1

JAMA , Volume 308 (4) – Jul 25, 2012

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Publisher
American Medical Association
Copyright
Copyright © 2012 American Medical Association. All Rights Reserved.
ISSN
0098-7484
eISSN
1538-3598
DOI
10.1001/jama.2012.6807
Publisher site
See Article on Publisher Site

Abstract

To the Editor: Dr Wahbi and colleagues1 concluded that sudden death mortality was improved in patients with myotonic dystrophy type 1 (DM1) and moderate conduction abnormalities on electrocardiogram who underwent an invasive strategy consisting of an electrophysiological study followed by prophylactic pacing if the HV interval exceeded 70 milliseconds. In our opinion, there are uncertainties in how the retrospective observational trial was conducted and reported that limit the ability to determine if their invasive strategy was associated with a survival advantage. It is not clear how patients were selected for the invasive strategy group or for the noninvasive strategy comparison group. The authors excluded patients receiving pacing devices based on electrocardiogram criteria alone who should have been included in the noninvasive strategy group. None of the 145 noninvasive strategy patients received a pacing device during follow-up. Conduction disease is progressive in DM1 and it would be atypical that none of the patients would have developed severe electrocardiogram abnormalities or bradycardia for which implantation of an antiarrhythmia device would have been prudent.2 It seems as if the noninvasive strategy group was merely observed rather than treated for arrhythmia risk and therefore does not form an appropriate comparison cohort despite the propensity score risk adjustment. Procedures requiring anesthesia, including the electrophysiological study, are not low risk in patients with DM1.3 Based on the forced vital capacity data, many of the patients had severe respiratory muscle involvement. The authors did not report procedural complications such as unplanned intubation or respiratory failure requiring prolonged hospital stay. The authors downplayed the fact that conduction disease in patients with DM1 is not only associated with a risk for complete heart block but also with a risk for ventricular tachyarrhythmias.4 It is not evident why only 14 patients received implantable cardioverter-defibrillators (ICDs) when 26 patients had inducible sustained ventricular tachyarrhythmias on the electrophysiological study. In nearly half of the pacemaker patients who died suddenly, ventricular fibrillation was the observed rhythm, raising the question of whether the ICD would be a more appropriate antiarrhythmia device in many patients with DM1. Back to top Article Information Conflict of Interest Disclosures: The authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Dr Groh reported receiving grants from the Muscular Dystrophy Association. Dr Bhakta reported no disclosures. References 1. Wahbi K, Meune C, Porcher R, et al. Electrophysiological study with prophylactic pacing and survival in adults with myotonic dystrophy and conduction system disease. JAMA. 2012;307(12):1292-130122453570PubMedGoogle ScholarCrossref 2. Bhakta D, Shen C, Kron J, Epstein AE, Pascuzzi RM, Groh WJ. Pacemaker and implantable cardioverter-defibrillator use in a US myotonic dystrophy type 1 population. J Cardiovasc Electrophysiol. 2011;22(12):1369-137522035077PubMedGoogle ScholarCrossref 3. Mathieu J, Allard P, Gobeil G, Girard M, De Braekeleer M, Bégin P. Anesthetic and surgical complications in 219 cases of myotonic dystrophy. Neurology. 1997;49(6):1646-16509409361PubMedGoogle ScholarCrossref 4. Merino JL, Carmona JR, Fernández-Lozano I, Peinado R, Basterra N, Sobrino JA. Mechanisms of sustained ventricular tachycardia in myotonic dystrophy: implications for catheter ablation. Circulation. 1998;98(6):541-5469714111PubMedGoogle ScholarCrossref

Journal

JAMAAmerican Medical Association

Published: Jul 25, 2012

References