Traumatic injuries were also on the rise, up 14 per cent from 2018.
"Māori and Pacific people with these injuries are likely to be younger and in higher areas of deprivation than other ethnic groups," Lane said.
As well as a growing number of emergency responses, paramedics also faced more complex jobs with patients who had multiple health issues, increasing the time that the job took, Lane said.
"It can take time to stabilise and treat patients with serious and complex conditions, meaning ambulances are not available to respond as quickly to the next call."
Over 10,000 people suffering stroke needed emergency ambulance response, up nearly 12 per cent from 2018.
Call-handlers at the St John 111 communication centres in Auckland and Christchurch answered more than half a million calls – 46,000 more than in 2018.
Ninety-two per cent of ambulance emergency calls were answered immediately, and 95 per cent within 15 seconds.
But despite the increasing demand the charity faced, Lane said St John was working hard to improve outcomes for patients as well as the safety for ambulance officers.