Widespread electroanatomic alterations of right cardiac chambers in patients with myotonic dystrophy type 1

Introduction: Conduction disturbances and arrhythmias characterize the cardiac feature of myotonic dystrophy type 1 (MD1); a myocardial involvement has been suggested as part of the cardiac disease. The aim of our study was to investigate the underlying myocardial alterations using electroanatomic mapping (CARTO) and their possible correlation with genetic and neurological findings. Methods and Results: Right atrial and ventricular CARTO maps were obtained in 13 MD1 patients. Thirteen age-matched patients with paroxysmal supraventricular tachycardia and normal heart served as controls. Unipolar voltage (UNI-v), bipolar voltage (BI-v) amplitudes, bipolar potential duration (Bi-dur), and atrial propagation time (A-pt) were measured. UNI-v and BI-v in interatrial septum, anterolateral atrial wall, and right ventricle outflow tract were lower in MD1 patients than controls (P < 0.001). Bi-dur and A-pt were longer in MD1 patients than controls (P < 0.001, P = 0.046, respectively). A significant relationship was documented between CTG triplets and the percentage of Bi-v <0.5 mV in the atrial anteroseptal region (r = 0.6, P = 0.02). Conclusions: Altered electroanatomic patterns are present in the right cardiac chambers in MD1 patients. Widespread myocardial alterations, not necessarily limited to the conduction system, may support the presence of a cardiac myopathy as part of the disease.