that he felt like his "heart is big" but does not have an irregular heart beat and doesn't notice it all with rest.; he felt like his "heart is big"; different beating of his heart; The patient said he has a little bit of anxiety; This is a spontaneous report received from a contactable reporter(s) (Other HCP) from medical information team.  A 25 year-old male patient received bnt162b2 (COMIRNATY), administration date 18Nov2021 (Batch/Lot number: unknown) as dose 2, single for covid-19 immunisation. The patient's relevant medical history and concomitant medications were not reported. Vaccination history included: Bnt162b2 (Dose Number:01), for Covid-19 Immunization, reaction(s): ""sore arm" after the first dose of the vaccine". The following information was reported: CARDIAC DISORDER (non-serious) with onset 22Nov2021, outcome "unknown", described as "that he felt like his "heart is big" but does not have an irregular heart beat and doesn't notice it all with rest."; HEART RATE ABNORMAL (non-serious) with onset Nov2021, outcome "unknown", described as "different beating of his heart"; ANXIETY (non-serious) with onset Nov2021, outcome "unknown", described as "The patient said he has a little bit of anxiety"; CARDIOMEGALY (non-serious) with onset 22Nov2021, outcome "unknown", described as "he felt like his "heart is big"".  Additional information: It was reported that, the patient received his second dose of the vaccine on 18Nov2021. Patient noticed yesterday, 22Nov that he felt like his heart was big, more so with activity but does not have an irregular heartbeat and does not notice it all with rest. Patient adds that the caller was pretty healthy. Patient did not experience this after his first dose; he only had a sore arm after the first dose of the vaccine. She explains she spoke with the patient and asked him if his heart feels like it was beating or pounding out of his chest and he said no. She asked if this feeling happens when at rest and he said no. She asked the patient did it feel like an irregular heartbeat, and he said no. The patient told the caller just feels like his heart was big and was like beating more than his heart normally would prior to receiving the second dose for COVID. So, she decided to call and see if there was any information she could get. The patient was worried about going back and working out until he knows everything was okay. The patient said he has a little bit of anxiety, but the caller does not feel like it was in his head. The patient explained it was like a different beating of his heart, it feels like his heart was big. Shared with caller that any information available in regards to the cardiac concerns with the vaccine is myocarditis or pericarditis. When enquired what are the percentage of some on having myocarditis, the response included emphasized with caller that myocarditis or pericarditis is not a diagnosis offered to caller; only that information is myocarditis or pericarditis is the information available with cardiac concerns and the vaccine. Referenced the attached document, that myocarditis was rare and that a specific percentage was not listed. No investigation assessment. The patient told the caller he did not have nothing at rest. She believed this to be not serious as she was watching him and he was active and working. The patient just was concerned on if he will be able to work out and was worried about whether he should or not since this has never happened before. The caller confirms she has no product information for either of the patient doses. She was not there when the patient received the vaccine, he just mentioned the symptoms to her. She does not know the date of when the patient received his first dose.   No follow-up attempts are possible; information about lot/batch number cannot be obtained. No further information is expected.