HEART ATTACK (Heart attack, Myocardial infarction) HIGH FEVER (Fever, Pyrexia) This spontaneous report received from a patient concerned an adult male. The patient's height, and weight were not reported. The patient's past medical history included aortic valve repair, and aortic valve replacement, and concurrent conditions included heart disorder.   The patient received covid-19 vaccine ad26.cov2.s (suspension for injection, route of admin, and batch number were not reported) dose was not reported, administered on 10-MAR-2021 12:30 for prophylactic vaccination. The batch number was not reported and has not been requested. No concomitant medications were reported. On 10-MAR-2021 at 19:30, the patient unexpectedly broke out into a very cold sweat, high fever, extreme stomach nausea, and his heart raced to levels he had never felt. The patient could not walk and could barley respond verbally to his fiancé for help. The patient was admitted to the hospital. The patient was taken on a wheelchair and was attended to immediately because of the severity of his condition. The emergency room doctors and nurses thought the patient was having a heart attack, as did he. The patient informed emergency room doctors and nurses that he had been given covid-19 vaccine ad26.cov2.s earlier in the day. After several hours of testing including electrocardiogram, computerized tomography scans, intravenous and constant blood pressure monitoring, it was determined that the patient should be transported to a hospital that was better equipped to service his apparent condition. Patient further states that he had an EKG, MRI, Nuclear stress test, CAT Scan and a Transesophageal ECHO, all of which "came back ok". He stated that there was also concern for brain damage, which was eventually ruled out. Patient states that he has no new additional diagnoses. He denies any current cardiac diagnoses or disorders. He spent 2 days in the hospital at 2 different facilities for testing and evaluation. He states that there were no other medications taken on the day or at the time of vaccination. He adds that there was no exposure to COVID-19. Reporter states that he had been tested twice for the virus for and upcoming flight/travel. He also added that he was also tested again at the hospital, all test were negative. He also added that he was also tested again at the hospital, all tests were negative. He also added that he had no other recent The hospital staff was concerned about a possible heart attack and not knowing the patient's history or having the equipment and staff to service this, they decided the past for "born-in" heart issues, the patient wanted to be transported to Medical Center where all of his doctors were residences. According to the patient, they had a fabulous team of world renowned cardiology experts from Cardiology. The hospital staff offered to send the patient to another General hospital. Both hospitals were about equal distance from original facility. The patient obviously wanted to go to where his doctors were and who know him personally for almost his whole life. According to the patient, the staff the hospital were fantastic, and as they stated to him verbally, probably saved his life. An ambulance ride followed at about 3:00AM on 11-MAR-2021 arrived at approximately 04:30 at Medical Center. The patient's cardiologist's covering doctors met him on the cardiology floor to immediately begin monitoring and performing every test at their disposal. The patient also informed the cardiology team at Medical Center that he had received the Covid-19 vaccine ad26.cov2.s vaccine on 10-MAR-2021 (Wednesday) afternoon. According to the patient, their eyes lit up immediately believing that the vaccine might had caused this. After almost 2 days and countless tests, blood screens, monitoring and consultation, the patient was released late afternoon on 12-MAR-2021 from hospital after being stabilized to a normal level. According to the patient's doctors, the only cause of these events could have been the Covid-19 vaccine ad26.cov2.s vaccine. According to the patient, visits and the almost 2 day stays. The patient's doctors had instructed him to stay close to home and continue to monitor his condition in the upcoming weeks because no one knows if these events could happen again.  The action taken with covid-19 vaccine ad26.cov2.s was not applicable. The patient recovered from heart attack, and high fever on 12-MAR-2021. This report was serious (Hospitalization Cause / Prolonged).  Additional information was received from patient on 26-MAR-2021. The following information was updated and incorporated into the case: Age group, age at the time of vaccination, medical history (aortic valve repair, and aortic valve replacement), lab test updated. Upon review, the follow information was amended: Seriousness criteria Other medical important condition removed for event Heart attack.