FROM NOSE BLOCK TO HEART BLOCK: A CASE OF INFLUENZA A CAUSING COMPLETE HEART BLOCK

Abstract

SESSION TITLE: Medical Student/Resident Cardiovascular Disease Posters SESSION TYPE: Med Student/Res Case Rep Postr PRESENTED ON: October 18-21, 2020 INTRODUCTION: Influenza is associated with cardiac complications such as myocarditis, congestive heart failure, and sudden death in hospitalized patients. It is also known to cause conduction blocks and cardiac arrest secondary to asystole and ventricular fibrillation. This is often overlooked as a cause of rhythm disorders due to the paucity of knowledge, and the rarity of the condition. CASE PRESENTATION: A 58-year-old female with a history first-degree atrioventricular block (AVB) presented with shortness of breath and cough for 3 days. On admission, she was febrile with a temperature of 100.5 degrees F and a normal chest x-ray. She tested positive for influenza A H1 N1. Her electrocardiogram (EKG) showed first-degree AVB with a PR interval of 300ms. However, on day 2, she had a syncopal episode and the telemetry strip revealed bradycardia with a 4.5-second pause. Her EKG showed a second-degree Mobitz type II that degenerated into a complete heart block. Electrophysiology was consulted, she underwent transvenous pacing. Her echocardiogram showed normal systolic function and chamber size, with no valvular abnormalities. She had an FDG positive emission tomography-cardiac sarcoidosis study which found no increased uptake to suggest an inflammatory/infiltrative process. She also had negative ischemia work up 6 months before hospitalization. The AVB was attributed to influenza after ruling out other causes. She subsequently underwent implantation of a dual-chamber his pacemaker with non-selective His bundle pacing. DISCUSSION: The pathogenesis of conduction disorders in influenza is believed to be secondary to myocarditis and inflammatory infiltrates pressing the conduction pathway with consequent necrosis in experimental models. It has also been hypothesized that inflammatory cytokines alter the electrical properties of endothelial cells which could explain why our patient had a complete heart block, without evidence of myocarditis (1). Hypoxia can cause AVB however, our patient was not hypoxic when the syncopal episode occurred. Hence, it is important to keep a close eye on patients admitted with influenza with an already compromised conduction system as there is a risk of potential worsening due to the inflammatory cytokines. Although the treatment of influenza is relatively simple, delay in initiating treatment may be fatal. Epidemiological studies have demonstrated decreased cardiovascular mortality in high-risk patients following influenza vaccination, so it is vital to educate patients about the importance of vaccination (2). CONCLUSIONS: Patients with an already compromised conduction system are at risk of worsening conduction blocks when faced with an inflammatory trigger. Most cases of conduction blocks secondary to influenza are temporary and resolve without a permanent pacemaker, however, cases with high degree block/complete heart block may warrant implantation of a permanent pacemaker. Reference #1: Warren-Gash C, Smeeth L, Hayward AC. Influenza as a trigger for acute myocardial infarction or death from cardiovascular disease: a systematic review. Lancet Infect Dis. 2009;9(10):601-10. Reference #2: Mamas MA, Fraser D, Neyses L. Cardiovascular manifestations associated with influenza virus infection. Int J Cardiol. 2008;130(3):304-9. DISCLOSURES: No relevant relationships by Ayesha Azmeen, source=Web Response No relevant relationships by Dimitrios Drekolias, source=Web Response No relevant relationships by Naga Vaishnavi Gadela, source=Web Response No relevant relationships by Jason Jacob, source=Web Response No relevant relationships by Mahati Paravathaneni, source=Web Response