Paramedics were delayed for 20 minutes trying to reach a man who had collapsed in a Cardiff park because the gates were locked, an inquest has heard.
Noel Acreman, 25, from Tonyrefail, Rhondda Cynon Taff, collapsed in Bute Park on 5 February.
Despite passersby trying to resuscitate him, he died from sudden cardiac death, Cardiff Coroner's Court heard.
The coroner recorded a conclusion of natural death and said emergency access to the park should be reviewed.
Philip Spinney, area coroner for south Wales central, said he would be writing to authorities asking them to review procedures over access to the park, which is behind Cardiff Castle.
The inquest heard Mr Acreman had been planning to propose to his girlfriend and was working as a tipper driver at Port Talbot steelworks.
He was due to go to work on 5 February but his car broke down. He told his parents, who he lived with at the time, he was going to go and have it repaired.
Sudden cardiac death
He went to Cardiff and was walking alone through Bute Park at about 15:50 when witnesses saw him collapse.
An ambulance was called, but paramedics could not reach Mr Acreman due to the gates.
Eventually, an off-duty firefighter, Thomas Winstone, who was in the park at the time, called his colleagues at Cardiff Central fire station to cut the locks.
The court was told paramedics and a doctor arrived 20 minutes after the 999 call was made.
Despite trying for another 30 minutes to resuscitate Mr Acreman, he was pronounced dead.
Mr Winston told the inquest: "The ambulance service didn't seem to have keys to get into the castle grounds and also they didn't contact the fire service themselves."
Dr Fouad Alchami, who carried out a post-mortem examination on Mr Acreman, said he had found no signs of illness and the only cause of death he could give was sudden arrhythmic death, known SADs.
He said any delay to treatment in cardiac cases could be "significant".