Paroxysmal atrial fibrillation; Patient presented with syncope; Tako-Tsubo cardiomyopathy; This spontaneous case was reported by a health care professional and describes the occurrence of ATRIAL FIBRILLATION (Paroxysmal atrial fibrillation) and SYNCOPE (Patient presented with syncope) in a 67-year-old female patient who received mRNA-1273 (Moderna COVID-19 Vaccine) (batch nos. 012F21A, 025A21A and 030M20A) for COVID-19 vaccination. The occurrence of additional non-serious events is detailed below.     No medical history was provided by the reporter.  Concomitant products included APIXABAN (ELIQUIS), PRAMIPEXOLE, PRAVASTATIN, EMPAGLIFLOZIN, METFORMIN HYDROCHLORIDE (SYNJARDY) and DULAGLUTIDE (TRULICITY) for an unknown indication.   On 18-Feb-2021, the patient received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) 1 dosage form. On 22-Mar-2021, received second dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) dosage was changed to 1 dosage form. On 23-Oct-2021, received third dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) dosage was changed to 1 dosage form. On 01-Nov-2021, the patient experienced ATRIAL FIBRILLATION (Paroxysmal atrial fibrillation) (seriousness criterion medically significant), SYNCOPE (Patient presented with syncope) (seriousness criterion medically significant) and STRESS CARDIOMYOPATHY (Tako-Tsubo cardiomyopathy). The patient was treated with DILTIAZEM (CARDIZEM [DILTIAZEM]) (intravenous) for Adverse event, at an unspecified dose and frequency; POTASSIUM for Adverse event, at an unspecified dose and frequency; LISINOPRIL for Adverse event, at an unspecified dose and frequency; CARVEDILOL for Adverse event, at a dose of carvedilol 12.5, bid; PARACETAMOL (TYLENOL [PARACETAMOL]) for Adverse event, at an unspecified dose and frequency; MORPHINE for Adverse event, at an unspecified dose and frequency; METOCLOPRAMIDE (REGLAN [METOCLOPRAMIDE]) for Adverse event, at an unspecified dose and frequency; MIDAZOLAM HYDROCHLORIDE (VERSED) for Adverse event, at an unspecified dose and frequency; HEPARIN for Adverse event, at an unspecified dose and frequency; DIPHENHYDRAMINE HYDROCHLORIDE (BENADRYL [DIPHENHYDRAMINE HYDROCHLORIDE]) for Adverse event, at an unspecified dose and frequency; FAMOTIDINE (PEPCID [FAMOTIDINE]) for Adverse event, at an unspecified dose and frequency; LEVOFLOXACIN (LOVENOX [LEVOFLOXACIN]) for Adverse event, at an unspecified dose and frequency; METOPROLOL TARTRATE (LOPRESSOR) for Adverse event, at an unspecified dose and frequency; ASPIRIN [ACETYLSALICYLIC ACID] for Adverse event, at an unspecified dose and frequency; GABAPENTIN (NEURONTIN) for Adverse event, at an unspecified dose and frequency; TOPIRAMATE (TOPAMAX) for Adverse event, at an unspecified dose and frequency; PRAVASTATIN SODIUM (PRAVACHOL) for Adverse event, at an unspecified dose and frequency; PRAVASTATIN SODIUM (PRAVACHOL) for Adverse event, at an unspecified dose and frequency; ESTRADIOL for Adverse event, at an unspecified dose and frequency; CLOPIDOGREL BISULFATE (PLAVIX) for Adverse event, at an unspecified dose and frequency and INSULIN for Adverse event, at an unspecified dose and frequency. At the time of the report, ATRIAL FIBRILLATION (Paroxysmal atrial fibrillation) and SYNCOPE (Patient presented with syncope) was resolving and STRESS CARDIOMYOPATHY (Tako-Tsubo cardiomyopathy) outcome was unknown.        For mRNA-1273 (Moderna COVID-19 Vaccine) (Unknown), the reporter did not provide any causality assessments.   The patient is stable now.  Company Comment: This case concerns a 67-year-old female patient with no relevant medical history, who experienced the unexpected adverse events of special interests of Atrial Fibrillation and Stress Cardiomyopathy and unexpected event of Syncope. The event occurred 10 days after receiving the third dose of mRNA-1273 Vaccine. The rechallenge was not applicable since only information about the third dose was disclosed. The benefit-risk relationship of mRNA-1273 Vaccine is not affected by this report.; Sender's Comments: This case concerns a 67-year-old female patient with no relevant medical history, who experienced the unexpected adverse events of special interests of Atrial Fibrillation and Stress Cardiomyopathy and unexpected event of Syncope. The event occurred 10 days after receiving the third dose of mRNA-1273 Vaccine. The rechallenge was not applicable since only information about the third dose was disclosed. The benefit-risk relationship of mRNA-1273 Vaccine is not affected by this report.