Gary Edgar, 31, went to an accident and emergency department after suffering severe pains in his arms and chest. His family claim he was sent home by staff at Monklands Hospital in Airdrie, North Lanarkshire, and told to take the painkiller.
However, the pains became worse but when he returned to the hospital three hours later he was sent away with same advice. The following day Mr Edgar was found dead on the floor of the home he shared with two of his brothers in Coatbridge.
Now his mother Elaine Boyle, 50, has criticised medical staff and called for an investigation into her son's death.
She said: "I just don't understand how this was allowed to happen. The hospital should have admitted him to do tests or at least kept him under observation.
"His heart should have been monitored and because it wasn't my son is now dead.
"Someone at the hospital should have thought 'this guy's been up here already and we sent him home, let's get him checked out'. I don't want this to happen to another family."
A spokesman for NHS Lanarkshire said: "We have been in contact with Ms Boyle and this matter is being dealt with through our formal complaints process.
"We have offered to meet with Ms Boyle to discuss her concerns."