had A.FIB; had chest pain; I had shortness of breath/ could not breath; On 28Jan2021 after my 2nd dose same things happened could not lay down flat and slept in chair for days; I have myocarditis; I have pericarditis; This spontaneous case was reported by a consumer and describes the occurrence of ATRIAL FIBRILLATION (had A.FIB), MYOCARDITIS (I have myocarditis) and PERICARDITIS (I have pericarditis) in a 54-year-old male patient who received mRNA-1273 (Moderna COVID-19 Vaccine) (batch no. 030L20A) for COVID-19 vaccination. The occurrence of additional non-serious events is detailed below.     No Medical History information was reported.  On 28-Jan-2021, the patient received second dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) 1 dosage form. On 28-Jan-2021, the patient experienced ATRIAL FIBRILLATION (had A.FIB) (seriousness criterion medically significant), CHEST PAIN (had chest pain), DYSPNOEA (I had shortness of breath/ could not breath) and POOR QUALITY SLEEP (On 28Jan2021 after my 2nd dose same things happened could not lay down flat and slept in chair for days). In 2021, the patient experienced MYOCARDITIS (I have myocarditis) (seriousness criterion medically significant) and PERICARDITIS (I have pericarditis) (seriousness criterion medically significant). At the time of the report, ATRIAL FIBRILLATION (had A.FIB), CHEST PAIN (had chest pain) and DYSPNOEA (I had shortness of breath/ could not breath) had not resolved and MYOCARDITIS (I have myocarditis), PERICARDITIS (I have pericarditis) and POOR QUALITY SLEEP (On 28Jan2021 after my 2nd dose same things happened could not lay down flat and slept in chair for days) outcome was unknown.     For mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular), the reporter did not provide any causality assessments.   On unknown date, Patient underwent MRI  lab test and results are unknown.  Patient was not able to lay down flat and slept in chair for days.  For Dose 1 symptoms, patient took steroids and experienced GI bleed from the medicine which is an old anti-inflammatory.  Patient takes medicines on regular basis and concomitant medication details were not provided.  No treatment information for symptoms after Dose 2 were provided.  Company Comment - This is a regulatory case concerning a 54 years old, male patient with no clinical history who experienced the unexpected events of ATRIAL FIBRILLATION, MYOCARDITIS, PERICARDITIS (AESIs events), CHEST PAIN and DYSPNOEA and other non-serious event. The events occurred the same day after the second dose of mRNA-1273 vaccine The rechallenge is not applicable" as the events occurred after the second dose and no details were provided about the first dose The benefit-risk relationship of mRNA-1273 vaccine is not affected by this report.   This case was linked to MOD-2021-384402 (Patient Link).; Sender's Comments: This is a regulatory case concerning a 54 years old, male patient with no clinical history who experienced the unexpected events of ATRIAL FIBRILLATION, MYOCARDITIS, PERICARDITIS (AESIs events), CHEST PAIN and DYSPNOEA and other non-serious event. The events occurred the same day after the second dose of mRNA-1273 vaccine The rechallenge is not applicable" as the events occurred after the second dose and no details were provided about the first dose The benefit-risk relationship of mRNA-1273 vaccine is not affected by this report.