A coroner has criticised health bosses following his third case in two years where a north Wales patient died after a delay in treatment.
John Gittins spoke out at the pre-inquest hearing of Lily Baxandall.
The 95-year-old, from Abergele, died last year after waiting in an ambulance at Glan Clwyd Hospital for four hours.
Mr Gittins said "the buck stops" with the health bosses and has called Betsi Cadwaladr University Health Board chief executive Trevor Purt, and his Welsh Ambulance Service Trust counterpart Tracy Myhill, to give evidence at the full inquest into Ms Baxandall's death later this year.
The pre-inquest hearing in Ruthin heard former catering supervisor Ms Baxandall was found by a cleaner on 1 September 2014, after falling and cutting her head.
After arriving at Glan Clwyd's emergency department at 17:00 BST her family said she remained outside in one of 11 ambulances waiting to discharge patients until 9.50 BST, by which time her condition had deteriorated.
A post mortem examination gave the provisional cause of death as pneumonia due to a subdural haematoma due to a head injury.
Following inquests into the deaths of Mr Pring and Mr Turner last year, narrative verdicts were returned and the coroner issued letters with a view to preventing future deaths.
Referring to these cases, Mr Gittins said he wanted to examine "whether things are changing."