Abstract 9482: Coronary Spasm in a Patient With Argininosuccinic Aciduria

Abstract

Case presentation: A 39-year-old male patient was referred for the treatment of hypertension. The patient had been treated for argininosuccinic aciduria (ASA) since eight months of age. Therapeutic drugs including, L-arginine, sodium phenylbutyrate and antiepileptic drugs had been administered. A detailed medical history taking revealed that the patient sometimes complained of chest discomfort under psychological stress. A 12-lead electrocardiogram showed abnormal q waves in lead III and aVF. Transthoracic echocardiography showed hypokinesis of left ventricular posterior wall. Endothelial function was quantified with brachial artery flow-mediated dilatation (FMD). The patient’s FMD value was 2.4% (normal cut off value 7.0%). Coronary computed tomography angiography showed no significant coronary stenosis. Cardiac magnetic resonance revealed transmural late gadolinium enhancement in the mid-ventricular level of the left ventricular posterior wall. The patient was suspected to have prior myocardial infarction. The patient was started on amlodipine and irbesartan, however, he continued to complain of chest discomfort at rest. Cardiac catheterization was performed to make a definitive diagnosis. The acetylcholine spasm provocation test revealed diffuse left and right coronary vasospasm. Transient ST-segment elevation with chest discomfort was observed. The patient was diagnosed as having coronary spastic angina. Chest discomfort was disappeared after additional administration of isosorbide mononitrate. Discussion: ASA is a genetic disorder of the urea cycle, caused by deficiency of argininosuccinate lyase (ASL). Specific laboratory findings are hyperammonemia, argininosuccinic acidemia and low plasma arginine levels. ASL is required to utilize extracellular arginine for NOS-dependent NO synthesis in endothelial cell. Reduction of ASL enzymatic activity leads to decline in NO production even if arginine is supplemented. Efficacy of NO supplementation for treatment of long-term complications in ASA patients has been reported. The precise mechanisms of coronary spasm remain to be elucidated. Our case report might support the significance of endothelial function in the pathogenesis of coronary spasm.