Arrhythmia; Heart rate that increased to 130-135/minutes and high heart rate sustained for hours and hours/ recorded heart rhythm of 283 beats for 38 seconds; Depression; Anxiety; Had symptoms like he was getting COVID again; Body aches; Fever; This case was received via an unknown source (no reference has been entered for a health authority or license partner) on 03-Nov-2021 and was forwarded to Moderna on 03-Nov-2021.    This spontaneous case was reported by a consumer and describes the occurrence of ARRHYTHMIA (Arrhythmia) and HEART RATE INCREASED (Heart rate that increased to 130-135/minutes and high heart rate sustained for hours and hours/ recorded heart rhythm of 283 beats for 38 seconds) in a 61-year-old male patient who received mRNA-1273 (Moderna COVID-19 Vaccine) (batch no. 029A21A) for COVID-19 vaccination. The occurrence of additional non-serious events is detailed below.     The patient's past medical history included COVID-19 in December 2020, Defibrillator/pacemaker insertion (He had a defibrillator and pacemaker put in him seven days after the first dose) in March 2021 and Implantable cardiac monitor insertion on 05-Mar-2021.   On 03-Mar-2021, the patient received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) 1 dosage form. In March 2021, received second dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) dosage was changed to 1 dosage form. In March 2021, the patient experienced ARRHYTHMIA (Arrhythmia) (seriousness criterion medically significant), HEART RATE INCREASED (Heart rate that increased to 130-135/minutes and high heart rate sustained for hours and hours/ recorded heart rhythm of 283 beats for 38 seconds) (seriousness criterion medically significant), DEPRESSION (Depression), ANXIETY (Anxiety), SUSPECTED COVID-19 (Had symptoms like he was getting COVID again), MYALGIA (Body aches) and PYREXIA (Fever). At the time of the report, ARRHYTHMIA (Arrhythmia), HEART RATE INCREASED (Heart rate that increased to 130-135/minutes and high heart rate sustained for hours and hours/ recorded heart rhythm of 283 beats for 38 seconds), DEPRESSION (Depression), ANXIETY (Anxiety), SUSPECTED COVID-19 (Had symptoms like he was getting COVID again), MYALGIA (Body aches) and PYREXIA (Fever) outcome was unknown.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On 05-Mar-2021, Heart rate: 238 (High) 283 beats for 38 seconds (3 days after first shot). In March 2021, Heart rate: 130-135 (High) Increased to 130-135/minutes.         No concomitant and treatment medications were reported.  In March 2021 patient got the first shot and second shot. Patient reported symptoms happened with the first and second shot. The patient had a loop recorder in him that recorded heart rhythm of 283 beats for 38 seconds (3 days after first shot).  Company Comment: This case concerns a 61-year-old, male patient with a history of COVID-19 in December 2020, Defibrillator/pacemaker insertion (He had a defibrillator and pacemaker put in him seven days after the first dose) in March 2021 and Implantable cardiac monitor insertion on 05-Mar-2021, who experienced the unexpected serious event of Arrhythmia and Heart rate increased and unexpected non-serious AESI event of suspected COVID-19. The events occurred approximately on the same after the first dose of Moderna COVID-19 vaccine and at an unknown date after the second dose of Moderna COVID-19 vaccine. The rechallenge was not applicable since the outcome of the events after the first dose was unknown. The medical history of COVID-19 in December 2020, Defibrillator/pacemaker insertion (He had a defibrillator and pacemaker put in him seven days after the first dose) in March 2021 and Implantable cardiac monitor insertion on 05-Mar-2021 remain as confounders. The benefit-risk relationship of Moderna COVID-19 vaccine is not affected by this report.     This case was linked to MOD-2021-058964 (Patient Link).; Sender's Comments: This case concerns a 61-year-old, male patient with a history of COVID-19 in December 2020, Defibrillator/pacemaker insertion (He had a defibrillator and pacemaker put in him seven days after the first dose) in March 2021 and Implantable cardiac monitor insertion on 05-Mar-2021, who experienced the unexpected serious event of Arrhythmia and Heart rate increased and unexpected non-serious AESI event of suspected COVID-19. The events occurred approximately on the same after the first dose of Moderna COVID-19 vaccine and at an unknown date after the second dose of Moderna COVID-19 vaccine. The rechallenge was not applicable since the outcome of the events after the first dose was unknown. The medical history of COVID-19 in December 2020, Defibrillator/pacemaker insertion (He had a defibrillator and pacemaker put in him seven days after the first dose) in March 2021 and Implantable cardiac monitor insertion on 05-Mar-2021 remain as confounders. The benefit-risk relationship of Moderna COVID-19 vaccine is not affected by this report.   Case was assessed as serious due to important medical event (as per reporter) and medical judgement.