AS-022 Effect of Triple Antiplatelet Therapy on Small Coronary Artery Treated with Zotarolimus Eluting Stent

Abstract

Introduction: Congenital long QT syndrome (LQTS) is a potentially lethal cardiac channelopathy and one of the leading causes of sudden cardiac death in the young. Disease prevalence is estimated nearly 1 in 3000 people. There have been impressive advancements in pathogenic mechanisms for LQTS, which enable us to classify the disease into different types. Long QT syndrome type 1 is triggered by exercise, associated with mutations in KCNQ1 gene which is responsible for slow component of the delayed rectifier repolarizing current (IKS). We report the case of type 1 LQTS based on the result of epinephrine QT stress testing. Case: A 20-year old man has been presented with syncope and seizure like episodes since he was 3 years old. These episodes usually lasted for 5-10 minutes and spontaneously subsided. His EKG showed a sinus rhythm with prolong QTc interval of 476ms. Diagnosed with congenital LQTS, he took propranolol and atenolol, which were effective until 19 years of age. However, after that, he felt fluttering and dizziness again. In most cases, this symptom developed after exercise, especially running. His family history was not significant for syncope or premature sudden death. His lab findings, 2-D echo and holter EKG test results were also unremarkable. Thus we conducted an epinephrine infusion test according to the protocol of Shimizu and Antzelevitch. Immediately after the bolus injection of 0.1μg/kg of epinephrine, the EKG showed marked prolongation of QTc from 512ms to 617ms. When he was challenged with isoproterenol after head up tilt test, blood pressure decreased accompanied by dizziness and nausea and T-alterans EKG pattern, Putting together his clinical history and provocation results, we made the diagnosis of a long QT syndrome, probably type 1. He was advised to avoid strenuous exercise and ensure regular full doses of beta-blocker. Conclusion: In this case, the most likely cause of the QT prolongation is exercise, but his several holter EKG indicated no ventricular tachycardia. A provocative test using epinephrine showed the marked increase in QTc interval. Therefore, the diagnosis is LQTS type 1, but further genetic tests are required to confirm that.