The aim of the study is to evaluate if the electrophysiological study (EPS) guided therapy, including the prophylactic implantation of implantable cardioverter defibrillator (ICD), in inducible patients, is able to improve survival in comparison with conventional therapy (CONV strategy) in Myotonic Dystrophy type 1 patients with conduction disorders.

Trial design:

This is a double-arm prospective observational study.

Patient population:

To be included in the study, DM1 patients had to have at least 18 years old, LVEF >35% on two-dimensional echocardiography, permanent pacing indication after non-invasive electrocardiographic evaluation or invasive EPS evaluation, according to the current guidelines. The following exclusion criteria were applied: electrolyte imbalance, thyroid disorders, prior cardiac surgery, prior cardiac arrest, prior spontaneous sustained ventricular arrhythmias, absuntion of antiarrhythmic drugs or medication known to affect cardiac conduction. All eligible DM1 patients underwent EPS for programmed ventricular stimulation; those in whom a sustained ventricula arrhythmia was inducible underwent subsequently ICD implantation. Non-inducible DM1 patients did not receive an ICD and underwent pacemaker implantation.

Endpoints:

The primary endpoint was all-cause mortality. Secondary end-points were sudden death (SD), death due to cardiac arrhythmias, ICD interventions and arrhythmic events in implanted patients.

Inclusion Criteria:

• MD1 diagnosis genetically confirmed
• LVEF >35% on two-dimensional echocardiography
• Permanent pacing indication according to the current guidelines

Exclusion Criteria:

• Electrolyte imbalance
• Thyroid disorders
• Prior cardiac surgery
• Prior cardiac arrest
• Prior spontaneous sustained ventricular arrhythmias

MD1 patients with permanent pacing indication and needed of sudden cardiac death screening.