Cardiovascular manifestations of myotonic dystrophy-1

Myotonic dystrophy (DM) is an inherited disorder transmitted in an autosomal dominant fashion and characterized by myotonia with dystrophic involvement of muscles and other multisystemic manifestations. It is the most common muscular dystrophy in whites. DM1, the most common type of DM, is associated with conduction defects, tachyarrhythmia, cardiomyopathy, and other cardiac disorders such as valvular diseases. The conduction defects in patients with DM1 are progressive; therefore, these patients should undergo careful work-up and follow-up, even if presenting with a benign conduction defect such as first-degree atrioventricular block. Atrial tachyarrhythmias are the most common arrhythmias in DM1, although ventricular tachycardia (VT) with a bundle branch re-entry mechanism can also occur. Interestingly, such VT can be cured by right bundle branch ablation with no need for an implantable cardioverter defibrillator. A significant portion of DM1 patients have heart failure, which is not clinically apparent, in part, because of the limited ability for exertion. Therefore, a low threshold should be used regarding when evaluating the heart by echocardiogram. Cardiovascular manifestations of DM1 have several important aspects that require careful attention and knowledge of the current evidence to make the best treatment decision. This article reviews the relevant DM1 literature and provides suggestions for diagnosis and treatment of patients with DM1.