Butterflies in the chest that went to quivering; quivering; A-Fib/Arterial fibrillation with rapid ventricular response; Arterial fibrillation with rapid ventricular response; cannot rule out anterior infarct and abnormal EKG; cannot rule out anterior infarct and abnormal EKG; trouble breathing; Her heart rate is screwed up; she feels so weak; irregular heart beat; This is a spontaneous report from a contactable consumer (patient). A 76-year-old female patient received bnt162b2 (PFIZER-BIONTECH COVID-19 VACCINE), dose 2 via an unspecified route of administration on 18Mar2021 (lot number: EP7534) as SINGLE DOSE for COVID-19 immunization. Medical history included asthma, chronic obstructive pulmonary disease (COPD), irritable bowel syndrome described as a condition where you're in the bathroom a lot, fibromyalgia, little depression, heartburn, upset stomach, heart fluttering issues, congestion spray (nasal congestion), and had part of a lung taken out. Family medical history included heart issues (dad and uncle). Concomitant medications included salbutamol (VENTOLINE [SALBUTAMOL]) for asthma; venlafaxine hydrochloride (EFFEXOR) for little depression; pantoprazole for heartburn and upset stomach; fluticasone propionate (lot number: AA47468, expiration date: Aug2020) for congestion spray (nasal congestion); fluticasone propionate, salmeterol xinafoate (ADVAIR) for heart fluttering issues. The patient previously took SHINGRIX (also reported as shingles vaccine, for clarification) for immunization and first dose of BNT162B2 (PFIZER-BIONTECH COVID-19 VACCINE, lot number: EN6200) on 25Feb2021 (age: 76 years) in the left shoulder for COVID-19 immunization. On 18Mar2021, right after taking the vaccine, patient started to experience quivering inside. Initially it felt like butterflies in the chest and then to quivering, it was then quivering the whole week. She knew she was going in for a test , an endoscopy, where they go down the throat. So she waited, the quivering did not go away for a whole week. It lasted until Friday before her endoscopy. When they found out, they sent her to ER at the hospital. They did not do the endoscopy. They said they might have to shock her heart or something. They wanted her to see the cardiologist right away. From the ER, she had 2 IVs, 1 in each arm. They were also taking blood every 4 hours (unknown results). The provided diagnosis was arterial fibrillation with rapid ventricular response and cannot rule out anterior infarct and abnormal EKG (Mar2021). The events cannot rule out anterior infarct and abnormal EKG, butterflies in the chest that went to quivering, A-Fib/Arterial fibrillation with rapid ventricular response resulted in emergency room visit and physician office visit and let to hospitalization. The patient was hospitalized from 2021 to an unknown date (also reported for 2 days, for clarification). It also gave her A-Fib, trouble breathing and now her heart rate is screwed up (Mar2021). On an unspecified date in 2021, she feels so weak and has irregular heartbeat. Therapeutic measures were taken as a result of the events which included Eliquis, Atorvastatin, Diltiazem, and other unspecified medications. The outcome of cannot rule out anterior infarct and abnormal EKG, butterflies in the chest that went to quivering, arterial fibrillation with rapid ventricular response, she feels so weak was not recovered; while the other events was unknown.