She came to the ER with complaints of chest pain and palpitations that developed while she was having a stress test.  EKG showed AFib with RVR and she was sent to the ER 1/26/22.  She had this pain intermittently on and off for the last several days with associated orthopnea and shortness of breath.  Orthopnea and shortness of breath worse during the night.  Chest pain described as heaviness.  Without any attenuating or accentuating factors.   In the ER-patient received it could told medications for the AFib and was put on heparin drip.  Also noted to have elevated troponin.  For the concern of pulmonary embolism-CT PA was ordered-pending.   COVID-19 vaccination status-received vaccination including booster.Admitted to hospital for acute systolic heart failure of unclear etiology, atrial fibrillation, elevated troponin, elevated proBNP, pleural effusion.  Cardiology consulted 1/26/22: 75/F with new onset afib/CMY presents with increased shortness of breath, Continue on heparin drip, Plan for cath in accordance with early invasive approach, May need cardioversion as some component possibly tachycardia induced,Continue on diuresis.    Echocardiogram showed EF 20-25%, moderate MR, moderately dilated left atrium and right atrium, mild-to-moderate TR, mild pulmonary hypertension, large pleural effusion.  Cath was done 1/27/22:  Impression: No significant coronary artery disease, Severely elevated left sided pressures.  Acute systolic heart failure - unclear etiology, ProBNP > 11000.  ? Vaccine related - received Moderna booster vaccination 1 week ?prior to hospitalization, negative respiratory panel, negative COVID-19 and influenza, negative RSV, pending lyme serology.    Intermittently confused.   D/C Summary Note: Hospital Course  This is a pleasant 75-year-old female with a past medical history of hypertension, hyperlipidemia, dementia, osteoarthritis, nicotine use, daily alcohol use, chronic GERD, fully vaccinated against COVID-19 including a 3rd booster (Moderna), who presented the emergency department with complaints of chest pain and palpitations during her outpatient stress test.  Apparently, 8 days after administration of her most recent booster, patient began developing shortness of breath and symptoms of congestive heart failure.  In the ER, EKG positive for atrial fibrillation with rapid ventricular response with heart rate of 107.  Troponin trended 691, 516, 563, 486.  BNP 10000.  Echocardiogram showed an ejection fraction of 20% with an RVSP of 38 with a large left pleural effusion.  Chest x-ray positive for evidence of congestive heart failure.  CT of the pulmonary arteries negative for PE.  Bilateral lower extremity ultrasound negative for DVT.  Patient met sirs criteria with heart rate of 110, respiratory rate 26.   Hemoglobin 16.5.  D-dimer 1.94.  TSH 3.89 with a free T4 of 1.31.  Respiratory viral panel negative.  Lyme serology negative.   Regarding her chest pain, present on admission.  At this point, likely secondary to vaccine induced (Moderna) myocarditis versus viral myocarditis.  Patient did have elevated troponins on admission.   These were noted to down trend.  Patient was taken for cardiac catheterization on 01/27/2022 which was negative for significant obstructive coronary artery disease and did note severely elevated left-sided pressures.  Continue with aspirin and statin.  Cardiology evaluation done.  Follow-up with cardiology in the clinic.  Follow-up with PCP as well.     Patient discharged home with LifeVest on 2/3/22.