This spontaneous case, reported by other health professional to Regulatory Authority and initially retrieved on 19-Oct-2018 by Seqirus from Regulatory Authority (regulatory reference number: IT-GLAXOSMITHKLINE-US2018GSK179262), concerns a patient of unspecified gender and age. The patient's historical condition included upper respiratory tract infection (reported as vague history of upper respiratory tract infection (URI) symptoms during the previous month), lightheadedness (reported as history of lightheadedness and fogginess with standing up too quickly or after eating), heart block first degree, Epstein-Barr virus infection, benign positional vertigo (reported as history of vertigo during the past 3 years which was thought to be consistent with Benign positional vertigo). The current conditions included sleep apnoea syndrome, allergic rhinitis, hypertension (reported as 5-years history). The patient's concomitant medications included acetylsalicylic acid, AMBIEN, lisinopril, Ibuprofen and hydrochlorothiazide for unknown indications. On 05-Feb-2014, the patient was administered FLUCELVAX (TIV) [dose: 0.5 ml, route of administration: intramuscular, batch number: 007021A, expiry date and anatomical location: not reported]. Seqirus reported that the provided batch number (007021A), does not match FLUVIRIN batch numbers and confirmed the suspect product as FLUCELVAX (TIV). Hence, the suspect vaccine was coded as FLUCELVAX (TIV). The co-suspect vaccine included Dtap (route of administration: intramuscular, dose, anatomical location, batch number and expiry date: not reported). On 07-Feb-2014, heart rate was found to be irregular. An electrocardiogram was performed (did not show significant changes from an unspecified date in 2010 unknown). On 19-Feb-2014, electrocardiogram, nuclear magnetic resonance imaging of heart, cardiac telemetry, CT angiography and Holter monitoring were performed (results were not reported). On the same day, 14 days after vaccination, the patient experienced atrioventricular block second degree/cessation of ventricular activity/Mobitz type II, myocardial oedema, viral myocarditis, arrhythmia, lymphadenopathy mediastinal and systolic dysfunction. On 20-Feb-2014, electrocardiogram and electrocardiogram ambulatory were performed (results were not reported). The creatine kinase-muscle/brain (CK-MB) test was found to be 8.9 and 5.8 (unit unspecified). Borrelia test performed showed absence of borrelia burgdorferi. The ejection fraction was 60-65 percent, cardiac troponin T was 0.15 and 0.13 (units and normal range unspecified). On 21-Feb-2014, the cardiac troponin T was 0.19, CK-MB was 4.2 (units and normal range unspecified), ejection fraction was 53 percent (mildly depressed, normal range unspecified). On 22-Feb-2014, the Cardiac troponin T was 0.14, CK-MB was 2.3 (units and normal range unspecified). On 23-Feb-2014, the Cardiac troponin T was 0.26, CK-MB was 1.8 (unit unspecified). On 24-Feb-2014, Hepatitis A antibody test was performed was negative (Hepatitis A Virus Ab, IgM, non-reactive). Hepatitis B core antibody was performed and the result showed Hepatitis B Virus Core antibody, IgM (reactive). Hepatitis B surface antigen test and Hepatitis C antibody test was non-reactive. Herpes virus test (reported as not detected), Influenza A virus test and influenza B virus test performed were negative. Computed tomography (CT) angiography, Epstein-Barr virus antibody, parvovirus B19 serology, cytomegalovirus antibody test and Coxsackie virus test were performed (results were not reported). On 25-Feb-2018, Hepatitis A antibody test and Hepatitis B Virus Core antibody were negative. The hepatitis B DNA assay were negative (result was reported as 'not detected'). Hepatitis B surface antibody, hepatitis B surface antigen and hepatitis C antibody were performed, and the results were non-reactive. The outcome of the events was unknown. The reporter assessed the case as serious (medically significant and hospitalized).