The 57-year-old man was rushed to the accident and emergency department by ambulance on Tuesday, reporting chest pain and twitching.
The man had a history of stroke, as well as hypertension and cardiac disease.
The hospital says the patient’s condition initially improved, but electrocardiogram testing later showed irregularities indicating a heart attack.
The doctor on call prescribed only drugs to stop him vomiting.
The man complained of chest pain again and was taken to the cardiac unit, where his condition deteriorated and he died on Wednesday.
“TMH expressed sincere apology for the wrong clinical judgment of myocardial infraction and failing to take into account family’s feeling when discussing the patient’s condition,” the hospital said in a statement.
It added that its medical department has reinforced to its doctors the need to pay attention to changes in ECG results and consult their seniors if in doubt.