Internal medicine

Heart failure

Ejection fraction

Cardiology

Left bundle branch block

Cardiac resynchronization therapy

Myotonic dystrophy

Medicine

The American Journal of Cardiology

Patients with type 1 myotonic dystrophy show reduced left ventricular systolic function in the presence of left bundle branch block due to electromechanical dys-synchrony. Our prospective study tracked a cohort of 64 type 1 myotonic dystrophy patients that demonstrated a high burden of atrial and ventricular arrhythmias and conduction delays. Of these patients, 12 (19%) patients had left bundle branch block, which was associated with reduced left ventricular systolic function. Eight of these patients received cardiac resynchronization therapy devices resulting in reduction of median QRS complex duration from 173 to 166 ms (p = 0.04), and improvement in median left ventricular ejection fraction from 37% to 46% (p = 0.007).

Comparison of Usefulness of Cardiac Resynchronization Therapy in Patients With Type 1 Myotonic Dystrophy With Versus Without Left Bundle Branch Block