Worsening LV function; Non-sustained ventricular tachycardia; This literature-non-study case was reported in a literature article and describes the occurrence of MYOCARDITIS (Worsening LV function) and VENTRICULAR TACHYCARDIA (Non-sustained ventricular tachycardia) in an 18-year-old male patient who received mRNA-1273 (Moderna COVID-19 Vaccine) for COVID-19 vaccination.      No Medical History information was reported.   On an unknown date, the patient received second dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) 1 dosage form. On an unknown date, received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) dosage was changed to 1 dosage form. On an unknown date, the patient experienced MYOCARDITIS (Worsening LV function) (seriousness criteria hospitalization and medically significant) and VENTRICULAR TACHYCARDIA (Non-sustained ventricular tachycardia) (seriousness criteria hospitalization and medically significant). The patient was treated with METOPROLOL SUCCINATE for Adverse event, at an unspecified dose and frequency; COLCHICINE for Adverse event, at an unspecified dose and frequency and IBUPROFEN for Adverse event, at an unspecified dose and frequency. At the time of the report, MYOCARDITIS (Worsening LV function) and VENTRICULAR TACHYCARDIA (Non-sustained ventricular tachycardia) outcome was unknown.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On an unknown date, Blood pressure measurement: 110/59 mmHg (Inconclusive) 110/59 mmHg. On an unknown date, Body temperature: 101 °F (High) 101 °F on presentation to hospital. On an unknown date, C-reactive protein: 74.2 (High) 74.2 mg/L (reference range: <10 mg/L). On an unknown date, Computerised tomogram coronary artery: normal (normal) normal; No coronary artery disease or anomalies. On an unknown date, Echocardiogram: lv systolic function was normal (normal) LV systolic function was normal (initial) and mild reduction in lvef to 50% (abnormal) mild reduction in LVEF to 50% (subsequent). On an unknown date, Ejection fraction: 59-50 (Inconclusive) 59-50 percent, 53 (Inconclusive) 53 percent and 49 (Inconclusive) 49 percent. On an unknown date, Electrocardiogram: demonstrated diffuse st elevations (abnormal) demonstrated diffuse ST elevations. On an unknown date, HIV test: negative (Negative) Negative. On an unknown date, Heart rate: 120 (Inconclusive) 120 beats per minute. On an unknown date, Influenza virus test: negative (Negative) Negative. On an unknown date, Laboratory test: elevated high-sensitivity troponin (abnormal) elevated high-sensitivity troponin. On an unknown date, Magnetic resonance imaging heart: mild hypokinesis of the mid lateral wall (abnormal) mild hypokinesis of the mid lateral wall; sub epicardial delayed enhancement in the lateral wall, sub epicardial enhancements (abnormal) sub epicardial enhancements in the same areas of T1 and T2 elevations, 1089-1097 (High) High and 64-72 (High) High. On an unknown date, Physical examination: unremarkable (normal) unremarkable. On an unknown date, Red blood cell sedimentation rate: 29 (High) (reference range: <15 mm/hour). On an unknown date, Respiratory syncytial virus test: negative (Negative) Negative. On an unknown date, SARS-CoV-2 test: negative (Negative) Negative. On an unknown date, Troponin: 7,206 - 32,140 (High) 7,206 - 32,140 ng/L (reference range: <15 ng/L). On an unknown date, Ventricular internal diameter: 4.8 (normal) Normal RV size and function; No valvular disease.     For mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular), the reporter considered MYOCARDITIS (Worsening LV function) and VENTRICULAR TACHYCARDIA (Non-sustained ventricular tachycardia) to be possibly related.    On an unknown date lab test included were LVEDVi: 101 mL/m 2 ; RVEDVi: 118 mL/m 2  Concomitant medications were not provided by the reporter. Action taken with the mRNA-1273 in response to the event is not applicable.   The patient's hospital course was complicated by brief episodes of non-sustained ventricular tachycardia.  Company Comment  Based on the current available information and temporal association between the use of the product and the start date of the events, a causal relationship cannot be excluded. Very limited information has been reported at this time.  Myocarditis is an AESI  which is included in the acute cardiac injury for mRNA vaccine. Continuous monitoring of this event is  expected.; Sender's Comments: Based on the current available information and temporal association between the use of the product and the start date of the events, a causal relationship cannot be excluded. Very limited information has been reported at this time.  Myocarditis is an AESI  which is included in the acute cardiac injury for mRNA vaccine. Continuous monitoring of this event is  expected.