An MP has called for an inquiry into why it took paramedics almost four hours to get to an 81-year-old woman, who died at the scene.
Marie Norris, who lived in Clacton-on-Sea, suffered chest pains on 1 January. She dialled 999 at 20:00 but paramedics got to her at 23:46.
Giles Watling, Conservative MP for Clacton, said her death was a "complete let down" and has called for a review.
The East of England Ambulance Service said demand had been "extremely high".
Sandy Brown, deputy chief executive at EEAST, said there had been more than 4,200 calls across the East of England that day, "more than 1,300 of which were in Essex".
"We have very publicly expressed how stretched the ambulance service is and the pressures our staff and the NHS as a whole have been under," he said.
The paramedics found Ms Norris was unconscious and not breathing.
Mr Watling said: "This death makes me very angry. We have a health service that's brilliant in so many ways and this is a complete let down.
"I am going to write to the secretary of state to get some answers and in this special case we need an inquiry."
Dave Powell, of the GMB union, which represents ambulance staff, said three more serious incidents in the north east of Essex were being investigated. He said Ms Norris' "tragic case does not appear to be isolated".
Sheila Hammond, secretary of the Tendring Pensioners Action Group, said the performance was not good enough.
"People in Clacton are worried about ambulance response times after the death of Marie Norris," she said.