heart palpitations; some very slight lesser functioning on the left side of her heart; atrial fibrillation; This is a spontaneous report received from contactable reporter(s) (Consumer or other non HCP) from medical information team. The reporter is the patient.  A 60-year-old female patient received BNT162b2 (BNT162B2), on 01Apr2021 as dose 2, single (Batch/Lot number: unknown) at the age of 60 years for covid-19 immunisation. The patient's relevant medical history and concomitant medications were not reported. Vaccination history included: Bnt162b2 (DOSE 1, SINGLE, Lot Number: Unknown), administration date: Mar2021, when the patient was 60 years old, for COVID-19 immunization. The following information was reported: PALPITATIONS (non-serious) with onset Apr2021, outcome "not recovered", described as "heart palpitations"; ATRIAL FIBRILLATION (medically significant) with onset 2021, outcome "not recovered"; CARDIAC DISORDER (non-serious) with onset 2021, outcome "not recovered", described as "some very slight lesser functioning on the left side of her heart". The events "atrial fibrillation", "heart palpitations" and "some very slight lesser functioning on the left side of her heart" required physician office visit. The patient underwent the following laboratory tests and procedures: Cardiac stress test: normal, notes: ordered stress test which was normal; Echocardiogram: decreased function on left side; Heart rate: elevated, notes: without medication heart rate would be elevated; below normal, notes: heart rate was going below normal, going into the 40s. Therapeutic measures were taken as a result of atrial fibrillation, palpitations, cardiac disorder.  Clinical Course: It was reported that patient and her husband are both over 60 and are both vegan. When possible, they try to avoid products derived from animals. That is one of the reasons they went with the Pfizer BioNTech Covid 19 vaccine. Caller was calling to inquire whether or not the new Abrysvo vaccine is vegan. Caller states that they try to use vegan products within reason and know sometimes things come from cell lines, and its not like a hamster or cow has to be slaughtered to make each vaccine. Same argument even from fetuses, that its a cell line not that its not continuous. She just wanted to let Pfizer know that when possible, it would be great if products were not manufactured using animal products. Caller, female, aged 63, states she is concerned about the atrial fibrillation side effect of Abrysvo because of a potential side effect she had after the second dose of the Pfizer BioNTech Covid 19 vaccine, the original formulation, second dose, three weeks after the initial one. Her husband, aged 65, has asthma, had no side effects but only had minor side effects like a sore arm, feeling a little beat up the next day. Each of them has had 6 shots of the Pfizer Covid vaccine, two of the initial and 4 boosters.  She only had a reaction after the second shot, not the boosters that are spaced out for 6 months. She suspects because of the closeness of the time table, just the three weeks instead of 6 months. And its not definite, she can't tie it all together but she experienced heart palpitations for the first time. But it wasn't like the next day, so she's not sure if it ties all together.  After having the palpitations, she had some testing and an echocardiogram done. Her doctor did notice  some very slight lesser functioning on the left side of her heart, that resolved itself after another few months and went away.  Again, not a definite cause and effect because it was only 3 weeks apart. She thinks it might have happened because it was only 3 weeks after the first dose. She had no bad reactions other of the Pfizer Covid vaccines other than minor sore arm with any of the subsequent boosters. But its not like she got the second vaccine and had palpitations the next day. She is a little reluctant to get the Abrysvo because of the heart side effects. She's had no bad reactions with any subsequent boosters other than a sore arm. All she knows is that in January she saw her family doctor in July and she did have palpitations. She believes she took shot in April, whenever they came out, then the other three weeks later. Then she was seen again by her primary care doctor in July and she did have palpitations.  She was referred to cardiology, and did a stress test, and showed slightly reduced function on the left side.  She doesn't remember the number but for example if 60 was normal, hers was 55. Another couple of months later, when she followed up, it was back to normal.  She still has palpitations since then but nothing that they can see on an echo. She heard that the Abrysvo had some incidence, that it can cause heart problems like A Fib. She is just concerned about that side effect because she had some heart palpitations and transient decrease in left side heart function after having the second dose of the original formulation of the Pfizer BioNTech Covid 19 vaccine. Outcome of reaction/event at the time of last observation: Unknown .Warm transfer from (name withheld) with Pfizer Medical Information: INT-01031786. Transfer agent has a patient on the other line who initially had questions about the new RSV vaccine, but caller stated after caller's 2nd dose of the Pfizer COVID vaccine original, had some heart palpitations and decreased function on left side of heart that has since gone away. Had 6 total doses of the Pfizer COVID vaccine. Caller stated caller's husband had sore arm, and maybe was feeling a little beat up next day, and caller had a similar type thing with all doses, only with caller's 2nd dose which caller thinks was on 01Apr2021, sometime after that caller started getting palpitations. Agent provided that caller was 63 years old, caller confirmed this but clarified that the palpitations and  decreased function on left side of heart would have started just before caller turned 61 years old, confirmed caller was 60 years old when these events started. Caller believes caller got the 2nd shot 01Apr2021 and thinks palpitations started shortly after that. Caller is on medication, clarified was put on metoprolol, is on the lowest dose but unknown what the dose is at time of call, stating the metoprolol was so effective that caller had to break pill in half for a lower dose, heart rate is fine now but was elevated before, without medication heart rate would be elevated but caller is on a very low dose now. Dose before was too much, heart rate was going below normal, going into the 40s, so broke dos in half, takes half a pill once a day. Decreased function on left side of heart.   Follow-up (30Aug2023): This is a spontaneous follow-up report received from the same contactable Consumer. This 60-Years-old female Consumer (patient) reported that: Updated Information Included: Reporter information [Mailing address. New reporter]. Patient information [DOB. Age. Height. Weight. Ethnicity. Race information]. Historical vaccine. Dose administration date. Event onset date. Treatment received. Event outcome. Physician office visit.  The information on the batch/lot number for BNT162b2 has been requested and will be submitted if and when received.; Sender's Comments: Linked Report(s) : US-PFIZER INC-202300289402 same patient and event, different dose;US-PFIZER INC-202300289404 same patient and event, different dose;US-PFIZER INC-202300289405 same patient and event, different dose;