An elderly woman died after waiting an hour for an ambulance to get to them, the coroner says.
The devastating case was detailed in a report released on Friday.
"Mrs Wells' death occurred in circumstances that are deeply troubling. Despite contacting St John concerning a life-threatening medical emergency, it took almost 70 minutes for an ambulance crew to arrive, due to scarce ambulance resources and competing demands," said coroner Mary-Anne Borrowdale.
Borrowdale said Margaret Wells, 78, was "unresponsive and unable to be saved" when an ambulance arrived at her home in the north Canterbury town of Ashley early September 20, 2020.
"The health, wellbeing and lives of New Zealanders depend on their ability to access emergency help in times of critical medical need. Communities expect and trust that emergency ambulance services will have the capacity to assist them quickly when they call for help."
Had an available ambulance been dispatched on the night of Wells' death, on September 20, 2020, she would've received emergency assistance some 25 minutes earlier than she did, Borrowdale said.
"Mr and Mrs Wells were elderly and alone, and Mr Wells was a double amputee who was unable to effectively aid Mrs Wells in her medical emergency. They were each entitled to expect a quicker response from St John, notwithstanding that its operational capacity is frequently stretched to its limits."
St John should've done more to ensure the couple weren't alone and without help or comfort, Borrowdale said.
Wells' chance of surviving the cardiac arrest was halved due to the ambulance delay, the coroner said.
"I accept the evidence of St John that its delayed response to Mr Wells' first emergency call contributed to, but did not cause, Mrs Wells' death."
St John clinical director Tony Smith admitted to the coroner it didn't "have enough resource to respond to the total workload".
Not assigning a crewed ambulance to Wells was a "regrettable error and an adverse event" that arose on a "very busy night in Canterbury, resourcing multiple incidents", Dr Smith said.
Dr Smith apologised "unreservedly for the failures associated with despatching an ambulance", the coroner's report said.
Had Wells' cardiac arrest happened after paramedics arrived, her predicted survival rate was 60 percent, Dr Smith told the coroner.
"St John has taken a number of actions to prevent these failures reoccurring. I commend the organisation for its honest self-appraisal and its willingness to make significant changes to its practices," Borrowdale said.
"Despite the value of these improvements - and they have the potential to be significant - as St John acknowledges, survival from an out-of-hospital cardiac arrest is a key measure of the clinical quality of an emergency ambulance service. In December 2020, St John's records show that it compared unfavourably against Australian states on this metric, as well as on the level of public spending to sustain the service."
