ATRIAL FIBRILLATION AS INITIAL PRESENTATION OF SMALL CELL LUNG CANCER

Abstract

SESSION TITLE: Monday Medical Student/Resident Case Report Posters SESSION TYPE: Med Student/Res Case Rep Postr PRESENTED ON: 10/21/2019 02:30 PM - 03:15 PM INTRODUCTION: Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia characterized by irregular, disorganized and rapid atrial activation leading to an irregular ventricular rhythm. The left atrium (LA) is highly susceptible to compression by extra-cardiac structures. Almost any cardiovascular condition can predispose to AF, common causes being hypertension, coronary artery disease, heart failure, valvular heart disease, cardiomyopathy, pericarditis. Extra-cardiac causes include thyrotoxicosis, chest trauma, thoracic surgery, obstructive sleep apnea, pulmonary embolism, medication use, alcohol excess, and withdrawal etc. We present a unique case of atrial fibrillation leading to a diagnosis of small cell lung cancer (SCLC). CASE PRESENTATION: We present a 74-year-old Caucasian female with significant past medical history of chronic obstructive pulmonary disease, coronary artery disease, sick sinus syndrome, hypertension, hyperlipidemia, and 70 pack-year tobacco abuse who presented with dyspnea and intermittent chest pain for last 3 days. Initial workup revealed a negative troponin trend, EKGs with non-ischemic changes. On the night of admission, patient's telemetry monitor revealed episodes of ventricular tachycardia. Subsequently, her pacemaker was interrogated and revealed runs of AF. Transthoracic echo was ordered which showed possible left atrial thrombus or mass in the LA. Interestingly enough, her previous echo just three months did not reveal any mass. A transesophageal echo was done for further evaluation which showed a large mass impinging on the LA and pulmonary veins. Computer Tomography (CT) scan of the heart revealed a 5.6 x 5.8 x 5.1cm subcarinal mass impinging on the left atrium and compressing the right pulmonary vein. The patient was taken for an endo-bronchial ultrasound with fine needle aspiration of the mass, and the pathology revealed SCLC. DISCUSSION: Though rare and often difficult to establish, there are several case reports that show an association between external compression of the LA and AF. Our patient interestingly had a benign echo just 3 months prior not showing any structurally normal heart. Previous imaging with CT Chest one year prior did not reveal subcarinal mass compressing the LA. As so, this highlights the aggressive nature of SCLC. SCLC is commonly seen in about 10-15% of lung cancers. It is a rapidly growing cancer most often seen in smokers. It typically presents as a large hilar mass with lymphadenopathy or in central airways narrowing the bronchial lumen. CONCLUSIONS: In patients with high-risk factors of lung malignancy, it is important to maintain a broad differential of their presenting symptoms. It is important to arrange a close follow up with the care team, especially in those patients with chronic diseases that may mask an underlying malignancy. Reference #1: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5129693/ Reference #2: National Cancer Institute. Scientific Framework for Small Cell Lung Cancer (SCLC). June 2014. Available online: http://deainfo.nci.nih.gov/advisory/ctac/workgroup/SCLC/SCLC%20Congressional%20Response.pdf. Accessed April 29 2016. Reference #3: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5627048/ DISCLOSURES: No relevant relationships by Machaiah Madhrira, source=Web Response no disclosure on file for Ranjit Nair; No relevant relationships by Harsh Patel, source=Web Response no disclosure on file for Muhammad Tola