Could treating heart attacks in ambulances save more lives?

Published: 29 September 2026

A nationwide trial will investigate whether a new treatment approach for major heart attacks can improve survival and recovery.

A nationwide trial will test whether giving blood-thinning medicine in an ambulance, rather than waiting until hospital, could improve survival and recovery for people experiencing one of the most serious types of heart attack.

An estimated 2,000 to 2,500 people in New Zealand experience a STEMI heart attack each year, which occurs when a coronary artery, the blood vessel that supplies the heart with oxygen-rich blood, becomes completely blocked.

For someone having a STEMI heart attack, every minute counts. Without blood flow, the heart muscle begins to die.

Even when patients receive the best available treatment, around three in every 100 people die within 30 days. Many others go on to have another heart attack, stroke or heart failure.

Dr Sergej Cicovic, of Health New Zealand | Te Whatu Ora - Te Toka Tumai Auckland, has received a three-year Heart Foundation Project Grant to investigate whether treatment can start much sooner, within minutes of an ambulance arriving.

"For more than 20 years, we haven't made a major improvement in outcomes for people who have had this kind of heart attack," Sergej says.

"We focus a lot on what happens in hospital, but sometimes the biggest gains come from treatments delivered much earlier that are simple, cheap and effective."

Starting treatment sooner

Current treatment for STEMI heart attacks focuses on getting people to hospital as quickly as possible. There, they receive a blood-thinning medication called heparin before undergoing an emergency procedure to reopen the blocked artery.

However, heparin is usually not given until the patient reaches the cardiac catheterisation laboratory at hospital, often 30 to 90 minutes or longer after an ambulance first arrives.

The new study will investigate whether giving eligible patients heparin in an ambulance could stop the blood clot causing the heart attack from growing, improve blood flow to the heart and reduce permanent damage to the heart muscle.

"Time is muscle. The longer it takes to open that artery, the more heart muscle dies," Sergej says.

"If too much heart muscle is damaged, people can die or have long-term problems, such as heart failure and a weakened heart that can't pump blood effectively.

"But if we can open the artery earlier by giving heparin in an ambulance, we may be able to save more heart muscle and improve people's long-term outlook."

What the trial involves

The three-year trial will involve Hato Hone St John, Wellington Free Ambulance and hospitals across New Zealand that provide emergency heart procedures.

Around 2,500 patients who have had a STEMI heart attack will take part.

During different six-month periods, clinical teams will either give heparin earlier or continue with current standard treatment. All other parts of people's care will remain the same.

Researchers will assess whether people who receive heparin earlier have better blood flow through the blocked artery before the hospital procedure to reopen it.

The study will also examine whether earlier treatment reduces deaths, as well as repeat heart attacks and strokes in the 30 days after a STEMI heart attack.

Because heparin is a blood-thinning medicine, researchers will closely monitor whether earlier treatment increases the risk of bleeding.

"We will also look at whether the blocked artery is more likely to partly reopen before hospital treatment, and how much heart muscle is saved," Sergej says.

A change that could be rolled out quickly

If the trial shows earlier treatment with heparin improves outcomes, the change could be introduced nationwide relatively easily.

Paramedics already carry heparin and are trained to administer it, meaning no new equipment or major training programme would be required.

"The impact could be rapid and far-reaching," Sergej says.

"Ambulances already carry heparin. Introducing this treatment nationwide would require only a simple change to the national ambulance protocol, with no new equipment, training or extra cost.

"This means a potentially life-saving change could reach every corner of New Zealand within months of the trial results."

The findings could be vital for people living in rural communities, where longer travel times to hospital can delay treatment.

"The findings could matter most for people living rurally, where longer journeys to hospital delay treatment, and for Māori and Pacific peoples, who experience STEMI at younger ages and have worse outcomes."

Potential to improve heart attack care across New Zealand

Heart Foundation Medical Director Dr Gerry Devlin says the research has the potential to improve treatment for STEMI heart attack patients across the country.

"Heart attacks do not wait until someone reaches hospital," he says.

"Sergej's research could show that a small change at the start of a patient's journey leads to better recovery and saves lives, regardless of where people live in New Zealand.

"Because heparin is low-cost, readily available and already carried by ambulances, a successful trial could see updated treatment protocols rolled out rapidly across the country."