Redefining Unstable Angina with High-sensitivity Cardiac Troponin

Most people who come to hospital with chest pain do not have a heart attack, but still need to have a blood test to measure a protein called troponin which is released when the heart is damaged.

We recently found that by using a more sensitive troponin test we can identify people without a heart attack at a very early stage, and most can be safely discharged home from the Emergency Department. This test is so sensitive it can measure troponin in nearly all people at very low levels.

We have found that very small amounts of troponin, even when below the levels used to diagnose a heart-attack, can predict future heart attack and death.

We think this is because low-levels of troponin are due to unstable disease of the heart arteries and that this information will help us identify people with a condition called unstable angina more accurately.

We wish to use this information to identify those at the highest risk of future heart attack and evaluate whether further testing and treatment for heart artery disease will reduce this risk. To do this we will carry out three research studies.

In the first study we will review data collected from a previous trial, and investigate how we can define these patients who have the highest risk, and who we believe have a new definition of unstable angina.

At the same time, in Study 2, we will also assess if the blood troponin level can predict abnormalities on CT scan of the heart.

We will also assess if there are extra protein markers in the blood of patients who have the highest risk of future heart-attacks.

In Study 3, we will then investigate if we can reduce the risk of heart attacks in those patients who meet our new definition of unstable angina, by starting them on treatments like aspirin or statins if they have disease on a CT of their heart.

Study 3 will be a randomised control trial across 6 hospitals in Scotland, meaning half of the patients recruited will not get a scan, and not have new drugs started.

This will allow us to assess if doing these extra scans and starting extra medication has a significant and real benefit for patients.