Introduction: Since 2012, we have successfully implemented endocardial ablation procedures in patients with structural heart disease and ventricular arrhythmias (1). These are complex electrophysiology (EP) procedures that are used to treat recurrences of ventricular arrhythmias. However, in some patients endocardial ablation is unsuccessful, since the key substrate of arrhythmia is subepicardial.

Case report: We report a 20-year-old patient without previous medical history, who has survived out-of-hospital arrest, caused by ventricular fibrillation (VF). The patient was successfully defibrillated, and after the therapeutic hypothermia there was complete neurological recovery. Extensive cardiac work up followed: the 12-lead ECG did not show signs of electrical diseases, and the echocardiographic finding was completely normal. Coronarography showed no coronary artery disease and EP study excluded accessory pathway, Brugada and long QT interval syndrome. Before implanting cardioverter defibrillator (ICD), magnetic resonance was performed and a substrate of arrhythmia was found in the form of subepicardial scar zones in the left ventricle, probably a consequence of myocarditis. Despite multiple antiarrhythmic drugs, the patient had frequent recurrences of VF with multiple ICD shocks. As the substrate of arrhythmia was clearly epicardial, we opted for percutaneous endo/epi procedure. Procedure was performed in the EP room in general anesthesia with invasive hemodynamic monitoring and cardiac surgery on call in case of emergency. The subxiphoid epicardial approach was achieved using Tuohy needle with the help fluoroscopy and small contrast injections. The multipolar catheter was used for substrate mapping of the endocardial and epicardial surfaces. Hence, the target ablation zones were defined. Before epicardial ablation, coronarography was performed to confirm the absence of large arteries in the target zone. The procedure and postprocedural course were without complications, and in the 18 month follow-up the patient was without recurrence of arrhythmia, without specific antiarrhythmic therapy. Due to the high complexity of the procedure, so far these patients have been referred to colleagues overseas. Recently, epicardial ablation of ventricular arrhythmias is also possible in centers in the Republic of Croatia.