felt like heart attack; had an episode of Afib; passing out; chest pains; sweats; migraines; cardiac issues; interchange of vaccine products; This is a spontaneous report received from a contactable reporter(s) (Consumer or other non HCP) from medical information team. The reporter is the patient.  A 43-year-old male patient received BNT162b2 (BNT162B2), in Dec2021 as dose 3 (booster), single (Batch/Lot number: unknown) for covid-19 immunisation. The patient's relevant medical history and concomitant medications were not reported. Vaccination history included: Moderna covid-19 vaccine (DOSE 1, SINGLE), for COVID-19 immunization; Moderna covid-19 vaccine (DOSE 2, SINGLE), for COVID-19 immunization. The following information was reported: INTERCHANGE OF VACCINE PRODUCTS (medically significant) with onset Dec2021, outcome "unknown"; CARDIAC DISORDER (non-serious) with onset 10Jan2022, outcome "unknown", described as "cardiac issues"; MYOCARDIAL INFARCTION (medically significant), outcome "unknown", described as "felt like heart attack"; ATRIAL FIBRILLATION (medically significant), outcome "unknown", described as "had an episode of Afib"; LOSS OF CONSCIOUSNESS (medically significant), outcome "unknown", described as "passing out"; CHEST PAIN (non-serious), outcome "unknown", described as "chest pains"; HYPERHIDROSIS (non-serious), outcome "unknown", described as "sweats"; MIGRAINE (non-serious), outcome "unknown", described as "migraines". The patient underwent the following laboratory tests and procedures: Magnetic resonance imaging heart: unknown results. Clinical course: Patient had significant cardiac issues since the booster in Dec2021 (3 weeks later felt like heart attack) after 2 previous moderna vaccines. Patient never had covid. There were things circulating at the time that were better protected if had the other brand and the store patient went to had the Pfizer vaccine. So he had that. He received the booster in the beginning or middle of Dec2021, then on 10Jan2022, 3 or 4 weeks after the booster, he had serious cardiac issues and events that developed on 10Jan2022 and had to go through 6 months of testing and still had what they called pre atrial contractions all the time, and other weird stuff. Patient was not too concerned about it what it really was this mess with one of the females, his daughter had an event. And his father had a heart attached a week after his booster, so patient was thinking genetically something may not be jiving. Father had heart attack. His last thing was talking about in December, had adverse things, and also migraines terrible for about 3 months. They went away. It was 3 - 4 months after had the booster, that he had the cardiac events that scared the heck out of him that sent him down the path of troubleshooting route, all the way up to cardiac MRI. Patient had an episode of Afib, which he had never had. His heart stopped beating for a second and he started passing out. And he started with chest pains. He almost passed out; He went to the ground. There were sweats, chest pain, and he was this close to going to the ER, didn't go because he started feeling okay, didn't want to go to the hospital because of Covid, he wound up going to see his cardiologist the next day. That was when they went down the path of starting to test him for what was going on, with halter monitors, and things of that nature, then in all the halter monitors and studies they found the PACs, SVTs, and one episode captured of Afib on one of the devices.  The information on the batch/lot number for BNT162b2 has been requested and will be submitted if and when received.