Frequent PVC, Palpitation; aortic aneurysm; neuropathy; chest pain; myocarditis; The third dose was an overdose. They gave twice the recommended dose.; This spontaneous case was reported by a patient and describes the occurrence of VENTRICULAR EXTRASYSTOLES (Frequent PVC, Palpitation), AORTIC ANEURYSM (aortic aneurysm), NEUROPATHY PERIPHERAL (neuropathy), CHEST PAIN (chest pain) and MYOCARDITIS (myocarditis) in a 54-year-old male patient who received mRNA-1273 (Moderna COVID-19 Vaccine) for COVID-19 prophylaxis. The occurrence of additional non-serious events is detailed below.     Prior to vaccination, he had no heart problems. He did not receive other vaccines within 4 weeks of Moderna COVID-19 vaccine. He was not on any medications when getting vaccine or before vaccination. He never had COVID disease, and he never had a positive PCR test. Patient was healthy.    In 2021, the patient received second dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) 1 dosage form. In 2021, received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) dosage was changed to 1 dosage form. In December 2021, received third dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) dosage was changed to 1 dosage form. In December 2021, the patient experienced OVERDOSE (The third dose was an overdose. They gave twice the recommended dose.). On an unknown date, the patient experienced VENTRICULAR EXTRASYSTOLES (Frequent PVC, Palpitation) (seriousness criterion medically significant), AORTIC ANEURYSM (aortic aneurysm) (seriousness criterion medically significant), NEUROPATHY PERIPHERAL (neuropathy) (seriousness criterion medically significant), CHEST PAIN (chest pain) (seriousness criterion medically significant) and MYOCARDITIS (myocarditis) (seriousness criterion medically significant). The patient was treated with GABAPENTIN at a dose of stopped because side effects and IMMUNOGLOBULIN HUMAN NORMAL (IMMUNOGLOBULIN [IMMUNOGLOBULIN HUMAN NORMAL]) at an unspecified dose and frequency. At the time of the report, VENTRICULAR EXTRASYSTOLES (Frequent PVC, Palpitation), AORTIC ANEURYSM (aortic aneurysm), NEUROPATHY PERIPHERAL (neuropathy), CHEST PAIN (chest pain), MYOCARDITIS (myocarditis) and OVERDOSE (The third dose was an overdose. They gave twice the recommended dose.) outcome was unknown.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On an unknown date, Electrocardiogram: abnormal with Frequent PVC. On an unknown date, Heart rate: decrease in Heart Rate (high 30's).         Concomitant product use was not provided by the reporter.  Patient had his first primary dose on Mar-2021 or in Apr-2021 and patient had his second primary dose on Apr-2021 or May-2021.  It was reported that Within 1 month after the 3rd dose, he had a decrease in Heart Rate (high 30's), palpitation, and Frequent PVC. He visited emergency room, electrocardiogram (EKG) was performed which showed abnormal with Frequent PVC. They suspect Aortic aneurysm developing soon. He was told that there are slight changes in heart structure, Myocarditis, neuropathy, and he has Chest pain from time to time. He visited many doctors and did not want to provide their names.  Patient was treated with Gabapentin (stopped because of side effects) and IVIg immunoglobulin.  Company comment: This spontaneous case concerns a 54  year  old male patient, with no medical history reported, who received three doses with mRNA  1273 original vaccine and experienced the unexpected, serious (medically significant) events of ventricular extrasystoles (AESI), aortic aneurism, neuropathy peripheral, chest pain, and the expected serious event of myocarditis. The events occurred approximately one month after the administration of the third, booster dose; however, latency cannot be properly assessed since exact onset date and vaccination date were not provided. Overdose was also reported since the patient stated "The third dose was an overdose. They gave twice the recommended dose". The report stated that the patient had a decrease in Heart Rate (high 30's), and palpitation. He visited the emergency room, an electrocardiogram was done with "frequent PVC". It was reported that "they suspect Aortic aneurysm developing soon". He was told that there were "slight changes in heart structure, Myocarditis, neuropathy". He also reported he "has Chest pain from time to time". Gabapentin ("stopped because side effects") and intravenous immunoglobulin were reported as "new medicine", however, no further clinical details were provided for medical reviewing. The benefit-risk relationship of mRNA  1273 original vaccine is not affected by this report.