Discussion Heart failure is rare in Myotonic

Dystrophy type 1 and often occurs late in the course of the disease. The clinical recognition of heart failure in muscular diseases is more difficult than in patients with a normal muscular function, as fatigue is inherent to the muscular weakness and exercise tolerance is already impaired by the muscular disease itself. In DM1, the conduction system is always more extensively affected than the contractile myocardium and high degree AV blocks requiring pacemaker Inhibitors,research,lifescience,medical therapy are a well known complication of the disease. The typical ECG of DM1 patients depicts complete LBBB (5 to 25%) with first-degree AV block (20 to 40%). According to ESC 2007 Guidelines for Cardiac Pacing, permanent pacemaker implantation is indicated in DM1 patients with acquired third-degree or second-degree atrioSNS-032 ventricular (AV) block (class Inhibitors,research,lifescience,medical I B). There is also a class II B indication for first-degree AV block in neuromuscular diseases, when a family history of sudden death is reported. However, neither a clear consensus about biventricular pacing nor the usage of implantable Inhibitors,research,lifescience,medical cardiac defibrillator for patients with Myotonic Heart Disease exists. Basing on

the progressive deterioration of the left ventricular function, progression of AV conduction disturbances and occurrence of ventricular tachyarrhythmia, Said et al. (12) hypothesized Inhibitors,research,lifescience,medical a role for biventricular ICD in DM1 patients who need a permanent pacemaker implantation. Kilic et al. (13) described the first case of beneficial cardiac resynchronization in one DM1 patient with heart failure, complete LBBB and ventricular asynchrony, who was not

implanted of an intracardiac defibrillator, because no serious life threatening ventricular arrhythmias were induced in the EPS. In our patient, the early onset of heart failure could be related to the electromechanical delay caused by both intra- and inter-ventricular asynchrony, that leads to regional molecular changes in a non coordinate contracting myocardium and accelerates the progression Inhibitors,research,lifescience,medical of the heart failure. The spontaneous ventricular tachycardia, occurred in our patient at twelve months medroxyprogesterone follow up, suggests that the improvement in ejection fraction may not reduce the arrhythmic risk in these patients. Conclusion ICD-CRT can be a useful therapy in DM1 patients presenting with heart failure, cardiac dilatation with low EF, complete left bundle block and inducible ventricular tachy-arrhythmias because it improves left ventricular function, induces reverse remodelling and relieves symptoms of heart failure. It can be considered as a life-saving treatment, especially in patients at high-risk of inducible malignant ventricular arrhythmias, although the improvement in ejection fraction seems to not reduce the arrhythmic risk.