very dizzy; a very fast heartbeat that is on and off / traumatic heartbeat; This is a spontaneous report from a contactable consumer (patient). A 75-year-old female patient reported for herself that she received BNT162B2 (PFIZER-BIONTECH COVID-19 VACCINE, Solution for injection, Batch/Lot Number: Unknown), via an unspecified route of administration, administered in left arm on 28Apr2021 (age at the vaccination was 75 years) as DOSE 2, SINGLE for covid-19 immunisation. The patient medical history includes slow thyroid, blood pressure high and half deaf; all were ongoing. Concomitant medication included levothyroxine at 75 ug for slow thyroid and valsartan (DIOVAN) at 160-12.5mg for blood pressure high; both were from an unknown date and ongoing. The patient took first dose of BNT162B2 (Batch/Lot Number: EP7533) in her left arm for COVID-19 immunization and experienced little pain. The patient previously took Centrum since Mar2021. On 06May2021, the patient had a very fast heartbeat that is on and off and on 14May2021, the patient was very dizzy. Additional context reported as, the patient was a half deaf old lady so please talk slow. The patient was calling because patient got the COVID vaccine last month. The patient second dose was on 28Apr2021. About around a week after that, patient started experiencing an off heartbeat during the day. It was a very fast heartbeat. It has never happened before. The patient doesn't have a problem usually. Last year, patient had an electrocardiogram done, and everything was normal with no problems. The patient doesn't have diabetes or any illness. ECG done everything normal no problems. The patient mentioned that she did an EKG last August and it was normal, and that the patient had no other illness. On 14May2021, patient had an event, wrote it down because it was too traumatic for her. The patient got up and was making coffee at 7: 30 AM in the kitchen. Her heart was beating so hard. The patient had to hold her chest and the patient was very dizzy. The patient had to sit down. It was a good thing there was a chair in the kitchen. The patient had to sit for a while and put her head between her knees, and it took patient 10 minutes to re-join herself. The increased heart rate has been on and off since then. After that day thought, the patient has not had a traumatic heartbeat. But the patient does have an increased heartbeat sitting down reading and doing nothing. That was scaring her. It all started after the second dose. The patient wanted to report it. Yesterday, the patient called the FDA to report her side effect. They told her to call and let Pfizer know. The patient went to CVS pharmacy for the vaccine, did not have a prescribing doctor. The patient was a hiker, and usually hikes 4-5 miles a day. The patient tries to make sure her heart goes to 128. The patient didn't have any problems getting there. The patient had no problem with her heart rate until the second dose. The patient wasn't even walking fast, and her heart was beating so fast. It hasn't happened again where it was so strong that it made her dizzy like it did on 14May2021. Since then, her heart is beating off and on. The patient was scared because nothing like this has ever happened to her. The patient had no reaction to either vaccine. The patient had a little pain, but that was nothing. The patient had no reaction on her arm. The patient was so happy not to have side effects, no rash or shortness of breath. The patient was all good until this heart rate episode. The patient went to see the doctor 11May2021, two weeks ago. The patient gets a blood test every year to see if everything is normal. The patient forgot to tell her about the heartbeat and usually writes everything down because the patient will forget if she doesn't. The patient didn't write anything down for that blood work appointment, so she forgot to tell her about the heartbeat. The patient was walking 2 miles to get to the doctor, and her heartbeat was 99. The patient said it was normal because she was walking. The patient does take medicine for a slow thyroid. Levothyroxine at 75mcg, Diovan at 160-12.5mg for patient high blood pressure. The patient used to take centrum but usually stops it a month before her blood test to see how normal her blood test was. The patient hasn't taken the Centrum since Mar2021. The patient has never been in the hospital, has never had surgeries and doesn't have diabetes. The patient was a healthy woman. Outcome of the event very dizzy was unknown and other was resolving.