The woman, aged in her 70s, died at the Busselton Health Campus emergency department in April.
She had arrived by ambulance after suffering lower back pain but was forced to wait several hours to be seen and was not handed over to hospital staff, instead remaining under the supervision of non-paramedic transport officers.
An independent investigation has found the cause of death was the rupture of a dissecting thoracic aortic aneurysm, an extremely rare heart condition.
The review found it was unlikely the death could have been avoided if she had been immediately seen.
Health Minister Amber-Jade Sanderson, who provided a summary of the review on Tuesday, said the hospital had faced significant demand on the night with 16 ambulances ramped at one point.
She said the emergency department had been well staffed but it was still insufficient to deal with the unusually high activity.
"This was unprecedented and couldn't have been predicted," she told reporters.
"And it's also important to make the point that ... even if they had been seen quicker, it's unlikely that the outcome would have been different for this particular patient."
The government has accepted recommendations to install a dedicated emergency department coordinator to manage patient flow at Busselton Health Campus, as well as a nurse responsible for overseeing waiting patients.
St John Ambulance will meanwhile be required to notify the WA Country Health Service when ramping occurs to ensure hospital staff are supported.
WA has in recent months experienced high levels of ambulance ramping, where patients face long waits to be handed over to emergency departments.
The government, which is in negotiations with St John over its contract, has questioned why the ambulance provider did not immediately activate contingencies to deal with coronavirus-related furloughing.
The state opposition has blamed the government for failing to sufficiently invest in the health system's capacity.
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