P1736 An unexpected cause of ventricular tachycardia in a young patient

Introduction Hypoplastic coronary artery disease (HCAD) refers to a congenital underdevelopment of one or more coronary arteries, which are greatly reduced in diameter or length. It is a rare congenital abnormality which has rarely been documented in living patients and which may lead to myocardial infarction (MI) and sudden cardiac death (SCD). This case describes an otherwise healthy young male, which was admitted in the emergency department (ED) for repeated sustained ventricular tachycardia (VT) and was thereby diagnosed with an isolated hypoplasia of the left circumflex coronary artery (CX). Investigations revealed scar-related tachycardia, due to a prior silent myocardial infarction caused by HCAD. These findings were suggested by echocardiography and coronary angiography and were later confirmed by magnetic resonance and 3D cardiac mapping. Case Report A 34-year-old male patient was admitted to the intensive care unit with recurrent sustained VT causing hemodynamic instability. After receiving two electric shocks and amiodarone in the ambulance, the patient became hemodynamically stable. There was no remarcable medical history besides a syncopal fall 5 years before and no symptoms prior to the current event. Initial physical examination, ECG and laboratory testing were normal. Echocardiography revealed a dilated left ventricle with akynesia of the lateral wall and a mildly reduced ejection fraction (EF = 45%), moderate mitral regurgitation due to restriction of the posterior mitral leaflet. A subsequent emergent coronary angiography was therefore performed, which showed no sign of atherosclerotic lesions, yet it revealed a hypoplastic CX, without compensatory collateral vessels supplying the lateral wall. Cardiac MR demonstrated delayed enhancement with transmural necrosis and no viability in the lateral wall of the LV, suggesting a long-standing MI. Therefore, the final diagnosis was scar-related VT, due to a prior silent MI caused by HCAD. The management of this patient included implantation of an ICD in the secondary prevention of SCD. Moreover, we performed an EPS, which identified a scar at the level of the lateral and inferolateral LV walls as a substrate for VT (electroanatomic 3D voltage mapping) and of the critical istmus (3D activation mapping). The next step was radiofrequency ablation of the critical isthmus, with no inducibility of the VT after the procedure. After 6-months follow-up, there was no recurrence of the VT. Conclusion Finding the cause of myocardial infarction in a young patient with VT can be very challenging. We emphasise the role of imaging for the diagnosis and management of these patients. HCAD is a rare congenital anomaly, which can lead to progressive fibrosis in the territory with poor blood supply, MI and SCD. Although it is a rare condition, it should be considered in young adults who present with MI and/or SCD. Abstract P1736 Figure. Investigations