Myotonic dystrophy and cardiac conduction system abnormalities: How physician awareness affects the patient outcome?

摘要

In this case series, we present 7 consecutive patients with myotonic dystrophy presenting with recurrentlightheadedness, dizziness, near-syncope and fatigue. All had EKG evidence for intraventricular conductiondelay but only 5 had first-degree atrioventricular block. The HV intervals were greater than 72 msec in 5patients. Four had inducible sustained ventricular tachycardia during electrophysiology studies requiringimmediate cardioversion and received ICD. Two underwent permanent pacemaker placement due to completeheart block and infra-Hissian block. These electrophysiological findings are typical in patients with myotonicdystrophy.Five out of 7 patients were referred for arrhythmia evaluation in the last 2 years, suggesting an unusualsurge of referrals, which may be attributed to an increased awareness on the part of primary care physicians tothe cardiac manifestations of myotonic dystrophy.Since one-third of the cardiac deaths in these patients are sudden, prophylactic pacemaker placement isrecommended, despite minimal conduction system abnormality. However, the common practice is to identifypatients at high risk of conduction abnormalities by electrophysiology studies and to then provide those patientsat increased risk with prophylactic invasive strategies.There is a clear need for identifying the subgroup of patients with myotonic dystrophy and to interveneon behalf of those at high-risk of cardiac death with prophylactic invasive strategies. Identifying such patientsmay be difficult unless there is an increase in awareness among our primary care physicians.