Cardiovascular System - CDM


  • DM1-related cardiac pathology manifests predominantly as arrhythmias due to progressive abnormalities in the conduction system of the heart. Clinical presentations may include: presyncope, syncope, palpitations, dyspnea and, rarely, chest pain or sudden death from cardiac arrest.

  • Bradyarrhythmias (arrhythmias that cause a slowing of the heart rate) are not reported in literature under the age of ten years. Rarely, life-threatening tachyarrhythmias have been reported as young as ten. Although exact numbers of sudden cardiac death in children with DM1 or CDM are not known, they are thought to be very low.


  • Symptoms representing arrhythmias, sinus bradycardia, heart block, atrial fibrillation and flutter, orventricular tachycardia on ECG and systolic dysfunction on echocardiogram.

  • Symptom change, abnormal cardiac imaging, abnormal ECG.

  • Palpitations, dizziness, syncope, non–sinus rhythm.


  • Discuss the following tests with your doctor:

    • Evaluation of severity of cardiac rhythm disturbance via a 12-lead electrocardiogram (ECG), and long-term ambulatory ECG monitoring.

    • Serial ECG studies are useful to follow progression of conduction system abnormalities over time, as they are often asymptomatic.

    • Transient arrhythmia via 24-48 hour ambulatory holter ECG monitoring. Longer monitoring if the 12-lead ECG is abnormal or if symptoms are suggestive of an arrhythmia.

    • Cardiology evaluation with examination, ECG, echocardiogram, and ambulatory electrocardiographic monitoring should occur at the time of DM diagnosis, regardless of symptoms.

    • For individuals with normal LV ejection fraction and no evidence of the symptoms described prior, it is reasonable to reassess by examination, ECG, and ambulatory electrocardiographic monitoring annually and by echocardiogram every 2 to 4 years.


  • Use of emergency medical alert devices to identify DM1 diagnosis and risk of arrhythmia.

  • Be informed about the risks of arrhythmias and cardiac dysfunction and the importance of prompt medical attention if symptoms are observed (i.e. palpitations, pre-syncope, syncope, dyspnea, chest pain, unexplained fatigue).

  • Serial periodic clinical cardiology evaluation; specialist cardiology consultations are essential with abnormal electrocardiograms or cardiac symptoms.

  • Refer to:

    • In-hospital cardiac monitoring to detect arrhythmias if admitted for longer duration than typical following surgical procedures.

    • In-hospital cardiac monitoring if admitted due to severe illness or infection.