Summary: A cardiac arrest is when the heart suddenly stops pumping blood around the body and is a medical emergency. This project will validate the use of ‘MIRACLE2 Score’ by paramedics – this is a test that measures the chance of an out of hospital cardiac arrest (OOHCA) patient having suffered brain damage. If successful, the test will help to personalise the care of OOHCA patients and ensure that we make the best clinical decisions along the patient care pathway from the 999 call to the patient’s arrival at hospital.

A cardiac arrest is when the heart suddenly stops pumping blood around the body and is a life-threatening medical emergency. The brain can quickly become starved of oxygen and survivors of cardiac arrest unfortunately often sustain brain damage. If someone has a cardiac arrest in hospital, they may be saved by the specialised treatment on hand. However, there are around 60,000 out of hospital cardiac arrests (OOHCAs) every year in the UK and they have a strikingly low survival rate of only 10%, whereas survival would be much higher if they occurred in hospital.

Immediately after someone has an OOHCA, paramedics do not know whether they have suffered a brain injury. Without this information, all OOHCA patients follow a standardised pathway of care and only on arrival at hospital can they be fully assessed, which leads to significant delays in diagnosis and personalised treatment. If we could assess what is happening inside the hearts and bodies of OOHCA patients at the scene, we could make more strategic decisions about the best treatment for each patient. It is important to give people equal access to life­saving treatment, to know when aggressive, emergency care is needed, and when specialist, emergency cardiac teams should be activated.

MIRACLE₂ uses prediction modelling to accurately score someone’s risk of death following brain damage suffered during a cardiac arrest, or their chance of a good outcome. Seven variables are entered into the test to give a score between 1 and 10. The lower the score, the lower the likelihood of brain injury. The test has already been validated in hospitals and has shown great potential. By collaborating with the London Ambulance Service, the aim is to show that MIRACLE₂ works equally well in the community.

Incorporating this score with a digital approach will improve communication between paramedics and the medical teams standing by to receive patients. It has the potential to transform decisions on the best place to treat the patient, making it clearer whether patients should be sent to a heart attack centre, and help prepare hospital teams.

Ambulance crews take many OOHCA patients directly to a heart attack centre where they may receive specialist imaging, invasive heart tests and implantation of heart pump devices. These approaches have the potential to improve survival after cardiac arrest, but they are invasive and costly, and we still cannot identify which patients will benefit most from them. Predicting the likelihood of brain damage at the scene of cardiac arrest will give doctors the unprecedented ability to determine which interventions are necessary for each person.

Paramedics write down key information that they gather at the scene of OOHCA, but without the predictive scores, these details on their own do not tell us enough. Going digital, by inputting patient data on a tablet device at the scene and transmitting it directly to heart attack centres, will help to ensure we make the best clinical decisions along the patient care pathway from the 999 call to the patient’s arrival at hospital. It is hoped that the findings of the RAPID-MIRACLE study will play an important part in the development of national and international guidelines to improve care for OOHCA patients.