A 35-year-old male presents with exertional dyspnea, palpitations, shortness of breath, oliguria, and lower extremity edema for over 1 year. Symptoms worsened 1 week ago with sore throat, cough, productive cough with yellow sputum, and inability to lie flat at night. Echocardiogram (ECHO) shows dilation of both ventricles, diffuse hypokinesis, and left ventricular ejection fraction (LVEF) of 30%. He is on digoxin 0.25mg once daily with no significant past medical history. Based on the clinical presentation and investigations, the most likely diagnosis is: