Improving heart attack diagnosis - The TRAPID-AMI study

Key features

• Two year study: 2012 - 2014
• Sponsored by Roche Diagnostics
• 12-centre international study, including one UK site
• 140 patients recruited by the UK; joint highest internationally and the highest recruiting study on the NIHR Clinical Research Network (CRN) Cardiovascular Study Portfolio
• Research nurse support provided by the NIHR CRN, UK Chief Investigator supported by a NIHR Post-Doctoral Fellowship
• Chief Investigator: Professor Richard Body, Central Manchester University Hospitals NHS Foundation Trust

Chest pain is the most common reason why patients are admitted to hospital in an emergency. However, most admissions could be avoided with better diagnostic tests for acute myocardial infarction; commonly known as a heart attack.

Cardiac troponin T is a protein that is released into the blood when the heart muscle is damaged, and can therefore be an indicator of a heart attack. Until recently, patients were routinely admitted to hospital to test for levels of troponin T in the blood for up to 12 hours, due to the time it can take for levels to rise following a heart attack.

The aim of the TRAPID-AMI study was to demonstrate whether use of a high sensitivity test for troponin T would enable an accurate and more rapid diagnosis, in order to safely rule out heart attacks in the Emergency Department at an earlier stage. The study involved patients who presented to the Emergency Department within 6 hours of experiencing chest pain that doctors suspected had been caused by an acute coronary syndrome, including the possibility of a heart attack.

Written informed consent was taken in the Emergency Department and blood was drawn at the time of arrival. Further samples were drawn after 1, 2 and 4-14 hours. Research nurses followed patients up by telephone after 30 days, three months and one year. This was a commercial study sponsored by Roche Diagnostics. The 12-centre international study spanned nine countries, and included one UK site at Manchester Royal Infirmary. The study received research nurse support from the Injuries and Emergencies clinical specialty based within the NIHR Clinical Research Network (CRN), and delivery was also enhanced by the support of an NIHR Post-Doctoral Fellowship for the UK Chief Investigator.

The study recruited to time and target, with 140 patients recuited by the UK. This was the joint highest patient recruitment internationally, and also made it the highest recruiting study on the NIHR CRN’s Cardiovascular Study Portfolio.

Outcomes and findings

The TRAPID-AMI study resulted in two key findings:

• That by setting the cut-off at the detection limit of the high sensitivity troponin T test, a single blood test in the Emergency Department can rule out heart attacks in approximately one third of patients.
• A second blood sample taken one hour after arrival can rule out heart attacks in a further one third of patients, with high negative predictive value

Taking these two findings into account, this means that with the use of a high sensitivity troponin T test, approximately two thirds of patients with chest pain can be safely ruled out as having had a heart attack within one hour of arriving in the Emergency Department. In addition to this, the Bedside Evaluation of Sensitive Troponin (BEST) study is ongoing to evaluate whether these findings can be replicated with point of care troponin tests, which will further speed up decisions. Other important outcomes of the TRAPID-AMI study include:

• Evidence to suggest that patients with one very high result for high sensitivity troponin T can have a heart attack diagnosis confirmed immediately without the need for further tests, quantifying the cut-off required to achieve this.
• Demonstration of the value of gender-specific cut-offs to assist with the diagnosis of smaller heart attacks in women.

Value to the NHS

The findings of the study have been incorporated in European Society of Cardiology and NICE guidelines. Implementation of the high sensitivity troponin T test is estimated to save £100 million per year for the NHS, and will enable earlier reassurance without unnecessary hospital admission for up to 200,000 patients per year.

Professor Richard Body, Chief Investigator and Consultant in Emergency Medicine, Central Manchester University Hospitals NHS Foundation Trust:

“The results are incorporated in European Society of Cardiology and NICE guidelines. Implementation across the NHS will save an estimated £100 million per year for the NHS, and will enable earlier reassurance without unnecessary hospital admission for up to 200,000 patients per year.“

Key publications:

• Annals of Emergency Medicine, 2016
• International Journal of Cardiology, 2016
• Academic Emergency Medicine, 2016