A Broken Heart: Cardiac Arrest As the Initial Presentation of Myasthenic Crisis

Abstract

SESSION TITLE: Wednesday Medical Student/Resident Case Report Posters SESSION TYPE: Med Student/Res Case Rep Postr PRESENTED ON: 10/23/2019 09:45 AM - 10:45 AM INTRODUCTION: Myasthenic crisis (MC) is a life-threatening condition commonly associated with respiratory failure. MC is typically preceded by the worsening of myasthenia gravis (MG) symptoms, including limb, ocular and bulbar muscle weakness. However, MC may present in unusual ways. Isolated respiratory failure in MC without preceding symptoms of MG has been described in several case reports. There is paucity in the literature about the cardiac manifestations of MG. To our knowledge, we are the first to report MC manifesting with isolated cardiac arrest with PEA and a shortened PR interval. CASE PRESENTATION: A 61 year old male presented to the emergency room with upper respiratory infection symptoms including cough, fever, myalgia for three days prior to presentation. The patient admitted to having sick contacts at home. He did not any endorse limb, ocular or bulbar weakness.On initial physical exam patient had stable vital signs and no muscle weakness.Initial EKG showed normal sinus rhythm, shortened PR interval 96ms (120-200ms). Shortly after presentation patient was found to be unresponsive and was in cardiac arrest with pulseless electrical activity (PEA) on telemetry monitor. He was intubated and underwent CPR with the achievement of return of spontaneous circulation in 7 minutes and admitted to ICU. EKG post ROSC showed sinus tachycardia with shortened PR interval as before. Pulmonary embolism and pneumonia were highly suspected, but a CT angiogram of the chest and bronchoscopy were negative. Sepsis workup was noncontributory. Pre-exitation syndrome was ruled out by electrophysiology, it was suggested that the shortened PR could be due to enhanced AV node conduction. A diagnosis remained unclear until the patient’s prior history of myasthenia gravis was verified by his primary care provider. Treatment with plasmapheresis and methylprednisolone was initiated resulting in significant improvement of the patient’s condition. The patient fully recovered and was discharged to regular follow up and has remained stable. DISCUSSION: There is growing body of literature pointing towards cardiac involvement in myasthenia gravis (1). Striatial antibodies, including Anti-titin, Anti-RYR and Anti-Kv1.4 are present in 47% of the patients with MG. These antibodies cross-react between skeletal and cardiac muscles, and trigger inflammation and conduction abnormalities. Anti-Kv1.4 antibodies associated with EKG abnormalities, including QT prolongation and T-wave inversion in 60% of patients in one study (2). Association between MG and myocarditis, arrhythmia and heart failure has been described in retrospective studies and case reports.(3) CONCLUSIONS: Myasthenic crisis presenting as a cardiac arrest without other accompanying typical symptoms of MG is rare, and diagnostically challenging to providers. Clinicians should be aware of the possibility of cardiac manifestations in MG and be proactive in their approach. Reference #1: Limaye K, Vallurupalli S, Lee RW. Myasthenia of the Heart. Am J Med. 2016 Jun;129(6):e19-21. Epub 2016 Feb 1. Reference #2: Suzuki S. Cardiac involvements in myasthenia gravis associated with anti-Kv1.4 antibodies. Eur J Neurol. 2014 Feb;21(2):223-30. Epub 2013 Jul 5. Reference #3: Shivamurthy P, Parker MW. Cardiac manifestations of myasthenia gravis: A systematic review. IJC Metab Endocr. 2014 3-6 DISCLOSURES: No relevant relationships by Alexander Andreev, source=Web Response No relevant relationships by Farhana Begum, source=Web Response No relevant relationships by Sonu Sahni, source=Web Response No relevant relationships by Anjuli Singh, source=Web Response