NHS England has announced a new set of performance targets for the ambulance service which will apply to all 999 calls for the first time.
They say the new targets will save lives and remove long waits suffered by millions of patients.
Call handlers will change the way they assess cases and will have slightly more time to decide the most appropriate response.
NHS England say that as a result cardiac arrest patients could be identified quicker than ever before, with evidence showing this could save up to 250 lives every year.
Ambulances will now be expected to reach the most seriously ill patients in an average time of seven minutes.
The new system is backed by the British Heart Foundation, the Association of Ambulance Chief Executives, the Royal College of Emergency Medicine and the Stroke Association amongst others.
Simon Gillespie, Chief Executive of the British Heart Foundation, said: “When someone suffers a cardiac arrest, heart attack or stroke, it is absolutely vital that emergency services attend as quickly as possible to improve their chances of survival and reduce the risk of long-term disability. In the case of a cardiac arrest, bystanders should start CPR immediately and continue until the emergency services arrive.
“Following promising trial results, when the new system is introduced more widely we would expect emergency services to attend these life-threatening events more rapidly to ensure that every victim has the best chance of survival. The BHF will work with the NHS to monitor how well the new system works in practice and that the potential to save more lives is realised."