A Dublin GP is facing seven allegations of poor professional performance at a Medical Council fitness to practise inquiry.
Dr Sandor Endredi, who qualified in medicine in Hungary in 1977, was working for the Northdoc on-call service in Coolock, Dublin, where the allegations arose.
Anthony Geraghty, 32, arrived at the clinic in the early hours of 20 October 2009.
He had a complicated medical history.
It is alleged that Dr Endredi failed to take an adequate medical history or examination, failed to consider Mr Geraghty's cardiovascular history and failed to refer him to hospital.
Patrick Leonard, BL for the Medical Council, told the inquiry that Mr Geraghty had a history of heart disease, methadone maintenance, took benzodiazepines and had alcohol problems.
On 19 October 2009, his twin brother Damien noticed he was coughing and had difficulty breathing at his parents' house.
He decided to call the doctor on-call service for his brother to make an appointment at the clinic and they drove there quickly.
Mr Geraghty was seen at 12.15am on 20 October.
It is alleged that Dr Endredi diagnosed upper airways infection, a fast heartbeat and or drug and alcohol withdrawal syndrome.
He prescribed a heart drug, an antibiotic and Mr Geraghty was discharged home at around 1am.
The inquiry has heard that Mr Geraghty collapsed at home and was taken to the Mater Hospital, where attempts to resuscitate him failed. He died at 2am.
His sister Bernadette Daly told the inquiry that the family wanted answers about what happened.
They wanted to know why he was not sent to hospital by Dr Endredi.
Cathal Murphy, barrister for Dr Endredi, told the inquiry that defence medical evidence will be that the symptoms displayed by Mr Geraghty when seen by the GP had nothing to do with what he later died of.
He said that if the symptoms of heart attack had been present, Mr Geraghty would have displayed cell death at the post mortem examination, but this was not the case.