A man of 58 years old was hospitalized with acute abdominal pain, but he developed cardiac arrest and was admitted to the ICU after resuscitation. From electrocardiogram and echocardiographic findings, acute myocardial infarction was suspected. Following coronary angiography, we found 90% stenosis and thrombus in the #7 area of the left anterior descending artery, and performed thrombus aspiration and a stent insertion. However, decreased systemic vascular resistance and severe metabolic acidosis persisted, and as a result shoshin beriberi was suspected. We subsequently administered vitamin B₁ to the patient. The metabolic acidosis improved 12 hours later. Blood pressure and systemic vascular resistance increased smoothly, and the patient could be weaned from mechanical ventilation on his 5th day in the ICU. Afterwards, it was realized that the vitamin B₁ concentration in his blood at the time of admission was only 19 ng · ml^-1. He tended to drink beer in large quantities every day, and this is regarded as the cause of vitamin B₁ deficiency and the origin of the beriberi.