Respiratory Virus Infections in Acute Heart Failure

Inclusion Criteria: * Adult aged 19 years or older admitted to the cardiology department with acute heart failure * NT-proBNP \>300 pg/mL * Clinician judgement of possible respiratory viral infection (fever \>38 degrees or cough, respiratory symptoms such as sputum or consolidation on x-ray or CRP \>5 mg/dL) * Patients who have a nasopharyngeal swab for respiratory virus PCR test performed within 72 hours of admission for any of the 3 reasons Exclusion Criteria: * Patients with a clear other cause of acute heart failure (ex. ACS, bradycardia requiring a pacemaker, uncontrolled tachycardia, uncontrolled severe hypertension (SBP \>180mmHg or DBP \>110mmHg), haemoglobin \<7g/dL or AHF precipitated by medication non-adherence) * If the cause of pulmonary oedema is prominently attributed to exacerbation of CKD * If there is a clear other source of infection that can explain the fever