Artial Fibrillation; pulse rate ranged from 130bps to 180bps; This is a spontaneous report received from contactable reporter(s) (Consumer or other non HCP). The reporter is the patient.  A 67-year-old female patient (not pregnant) received BNT162b2 (BNT162B2), on 03Apr2022 as dose 4 (booster), single (Lot number: FK9895) at the age of 67 years, in right arm for covid-19 immunisation. The patient's relevant medical history included: "Arthritis" (unspecified if ongoing); "Fibromyalgia" (unspecified if ongoing); "mild mitral valve prolapse" (unspecified if ongoing), notes: mild mitral valve prolapse; "Known allergies: Latex" (unspecified if ongoing), notes: Known allergies: Latex. The patient's concomitant medications were not reported. Past drug history included: Fentanyl, reaction(s): "Known allergies: Fentanyl", notes: Known allergies: Fentanyl; Opiods, reaction(s): "Known allergies: Opiods", notes: Known allergies: Opiods; Valsartin, reaction(s): "Known allergies: Valsartin", notes: Known allergies: Valsartin. Vaccination history included: BNT162b2 (Dose Number: 3, Batch/Lot No: FC3184, Location of injection: Arm Right), administration date: 09Sep2021, when the patient was 66-year-old, for Covid-19 immunization; Bnt162b2 (Dose Number: 2, Location of injection: Arm Right), administration date: Mar2021, when the patient was 66 years old, for Covid-19 immunization; Bnt162b2 (Dose Number: 1, Batch/Lot No: EN6200, Location of injection: Arm Right), administration date: Feb2021, when the patient was 66 years old, for Covid-19 Immunization. The following information was reported: ATRIAL FIBRILLATION (medically significant) with onset 31May2022 at 13:00, outcome "not recovered", described as "Artial Fibrillation"; HEART RATE INCREASED (medically significant) with onset 31May2022 at 13:00, outcome "not recovered", described as "pulse rate ranged from 130bps to 180bps". The events "artial fibrillation" and "pulse rate ranged from 130bps to 180bps" required emergency room visit. The patient underwent the following laboratory tests and procedures: Heart rate: (31May2022) 130bps to 180bps; (04Jul2022) 150bps+; (11Jul2022) 150bps+; SARS-CoV-2 test: (03Aug2022) Negative. Therapeutic measures were taken as a result of atrial fibrillation, heart rate increased and was referred to cardiologist for evaluation and for treatment.  Clinical course: The patient received Pfizer bivalent formulation on 19Oct2022 as Dose 5 (Booster), single (Lot number: GH9693), in Right arm for covid-19 immunization received at Pharmacy or Drug Store. And all other previous doses were not bivalent. No other vaccine was received in four weeks. Patient had Levothyroxin, Buproprion, Duloxetine, Pravastatin within 2 weeks of fifth dose. On 31May2022 at 13:00, patient experienced Artial Fibrillation and was transported to ER for treatment, pulse rate ranged from 130bps to 180bps and on 04Jul2022 again experienced Artial Fibrillation and was transported to ER, pulse rate 150bps+, and on 11Jul2022 again experienced Artial Fibrillation and was transported to ER, pulse rate 150bps+, AFib was confirmed. No covid prior vaccination and was tested for covid post vaccination. The lot number for Dose 2 was reported as LN?2N6206.