cardiac decompensation; dyspnea; this is a spontaneous report received from a contactable reporter(s) (physician) from the regulatory authority-web. regulatory number: hr-halmed-300054178. other case identifier(s): 10-986-592-749. a 88 year-old female patient received bnt162b2 (comirnaty), intramuscular, administration date 20jan2022 (lot number: fn5519) as dose 3 (booster), single for covid-19 immunisation. relevant medical history included: "fibrillation atrial" (ongoing); "hypothyreosis" (ongoing); "diabetes mellitus" (ongoing); "ischaemic cardiomyopathy" (ongoing). concomitant medication(s) included: kalinor [citric acid;potassium bicarbonate;potassium citrate]; euthyrox taken for hypothyroidism; glucophage taken for diabetes mellitus; edemid; eliquis; byol. vaccination history included: covid-19 vaccine (dose 1, manufacturer unknown), for covid-19 immunization; covid-19 vaccine (dose 2, manufacturer unknown), for covid-19 immunization. the following information was reported: cardiac failure (death, hospitalization, medically significant) with onset 29jan2022, outcome "fatal", described as "cardiac decompensation"; dyspnoea (death, hospitalization) with onset 29jan2022, outcome "fatal", described as "dyspnea". the patient date of death was 30jan2022. the reported cause of death was cardiac failure. it was not reported if an autopsy was performed. clinical course: patient experienced events cardiac decompensation and dyspnoea 10 days after booster dose. concomitant therapy was eliquis 2x5 mg, euthyrox 50, glucophage st 750, byol 5 mg, edemid forte 125 kg and kalinor. reaction(s) / event(s) assessed: decompensation cardiac, dyspnea/source of assessment: regulatory authority, method of assessment: regulatory authority causality, result of assessment: unassessable/unclassifiable. adr is not adequately labelled for suspect drug comrinaty. events stop date on 30jan2022. no follow-up attempts are possible. no further information is expected.; reported cause(s) of death: cardiac decompensation with fatal outcome