Myocardial fibrosis and ventricular tachycardia in myotonic dystrophy type 1

Lithey C. Poveda-Conde, Unidad de Cardiología, Servicio de Cardiología Clínica, Clínica Universitaria Colombia; Facultad de Medicina, Fundación Universitaria Sanitas, Bogotá, Colombia
Nelson L. Moreno-Ruíz, Unidad de Cardiología, Servicio de Cardiología Clínica, Clínica Universitaria Colombia; Facultad de Medicina, Fundación Universitaria Sanitas, Bogotá, Colombia
Ingrid C. Rojas-Chaverra, Unidad de Cardiología, Servicio de Cardiología Clínica, Clínica Universitaria Colombia; Facultad de Medicina, Fundación Universitaria Sanitas, Bogotá, Colombia
Jesús A. Cotes-Millan, Facultad de Medicina, Fundación Universitaria Sanitas; Unidad de Radiología, Servicio de Imágenes Diagnósticas, Clínica Universitaria Colombia. Bogotá, Colombia

Myotonic dystrophy type 1 is a neuromuscular disorder associated with an increased risk of arrhythmias and sudden cardiac death, for which risk stratification remains a clinical challenge. We report the case of a 45-year-old woman with genetically confirmed myotonic dystrophy type 1 who presented with palpitations and dyspnea. Electrocardiography revealed sinus bradycardia and first-degree atrioventricular block, while Holter monitoring demonstrated a high burden of premature ventricular complexes and episodes of both non-sustained and sustained ventricular tachycardia. Cardiac magnetic resonance imaging showed late gadolinium enhancement involving 29% of the left ventricular mass, with a non-ischemic intramyocardial and subepicardial pattern consistent with extensive myocardial fibrosis. Based on the overall arrhythmic risk profile, an implantable cardioverter-defibrillator was implanted for primary prevention. During follow-up, no syncope, ventricular arrhythmias, or device therapies were documented. This case highlights the value of a multimodal approach to optimize arrhythmic risk stratification and guide individualized management.

Keywords: Myotonic dystrophy. Ventricular tachycardia. Magnetic resonance imaging. Implantable defibrillator. Sudden cardiac death.