Cardiac asthma or cardiac wheezing (CW) refers to a syndrome of dyspnea and wheezing that mimicks asthma clinically. Reported herein is the case of a 2-month-old boy who presented with refractory wheezing as a sign of cor triatriatum sinister (CTS) that culminated in overwhelming multiple organ failure in a short time. On the day of admission, oxygen saturation (SpO2 ) was <80%. Heart rate was 198 beats/min and respiratory rate 58 breaths/min. Chest radiogram showed pulmonary edema. Electrocardiogram showed right atrial enlargement and right ventricular hypertrophy. N-terminal pro-brain natriuretic peptide (NTproBNP) was very high at >20,000 pg/mL. Two-dimensional echocardiography with Doppler showed CTS, which was complicated with severe pulmonary arterial hypertension due to flagrant pulmonary venous obstruction. Cardiac surgery was undertaken, after which pulmonary edema subsided, SpO2 increased to ≥96%, and NTproBNP dropped to normal. He was discharged 11 days later, and was free of cardiac, pulmonary, renal, and neurological sequelae at 24 month follow up.