Simple blood test improves prediction of heart attack and stroke risk

A simple £5 blood test for the protein troponin could predict a person's risk of heart attacks and strokes with greater accuracy than ever before, research suggests.

Troponin is found in heart muscle cells and is released into the blood when the heart is damaged. High-sensitivity troponin blood tests are currently used in hospitals to diagnose heart attacks.

A new study led by the London School of Hygiene & Tropical Medicine (LSHTM) reveals the potential benefits of also using the tests routinely to spot people who might be at increased risk of heart problems.

The researchers found that testing for this protein can detect silent ongoing damage to the heart, a sign of a future risk of cardiovascular disease. They discovered that people with higher levels of troponin in their blood are at greater risk of a heart attack or stroke within 10 years.

For the study, published in the Journal of the American College of Cardiology, the team analysed anonymized health data of over 62,000 people from 15 studies in Europe, North America and Australia. Each person had their troponin levels measured, as well as conventional risk factors such as age, blood pressure, history of diabetes, smoking status and cholesterol levels. Participants were then tracked for around 10 years to see if they had a heart attack or stroke.

Current cardiovascular health assessments use an algorithm to predict people's risk of having a heart attack or stroke in the next 10 years based on their risk factors, including cholesterol levels measured using a blood test.

The researchers modelled the potential impact of adding troponin tests to conventional risk factors, and found the algorithm's predictions were up to four times more accurate than adding cholesterol results alone.

For people marked as being at intermediate risk during routine cardiovascular health assessments, the study suggested the tests would prevent one heart attack or stroke for roughly every 500 people tested.

Crucially, the modelling indicated that the troponin test was especially effective at spotting danger in the 35% of people currently found to be at this intermediate risk of cardiovascular problems. Depending on their age, people with a 2.5 to 15% chance of having a heart attack or stroke within 10 years are said to be at intermediate risk.

The intermediate risk group presents medical professionals with a problem, as the risk is not high enough to justify preventative treatment.

The modelling found that including the troponin tests meant that up to 8% of people originally classified as intermediate risk were changed to high risk. Giving preventative treatments like statins to these reclassified people could prevent many serious cardiovascular events, including heart attacks or strokes.

At £5, the troponin test would be considered cheap within the NHS for a diagnostic or predictive test, on par with the cost of cholesterol testing.

Troponin, even in the normal range, is a powerful indicator of silent heart muscle damage. As such, the test provides an extra layer of information that we can use to boost our accuracy when predicting people's risk. 

Incorporation of troponin into current cardiovascular risk estimation guidelines can be useful for identifying high risk individuals who will benefit from preventative treatment, reducing the risk of future circulatory problems."

Professor Anoop Shah, lead author of the study and Professor of Cardiovascular Medicine at LSHTM

Study author Dr Spencer Keene, Research Associate at the Cardiovascular Epidemiology Unit, University of Cambridge, said: "Cardiovascular risk prediction tools are designed to help apparently healthy individuals and their clinicians determine whether statins and other preventive therapies would be beneficial.

"Our study found that measuring troponin can help reduce uncertainty in this decision-making process, especially for individuals at intermediate cardiovascular disease risk, where the next steps are often unclear. Additionally, troponin measurement may further improve accuracy in older adults and those with diabetes.

"More research is needed to assess whether targeting troponin testing to these and other specific subgroups can improve screening efficiency, particularly when considering the costs and practical feasibility of implementation."

Professor Bryan Williams, Chief Scientific and Medical Officer at the British Heart Foundation, which funded the study, said: "Developments in risk prediction have helped doctors to build effective algorithms that can spot those most at risk of heart attacks and strokes. But, with around 100,000 hospital admissions for heart attacks alone in the UK each year, it's clear that there is still plenty of room for improvement.

"This new data suggests adding this blood test to current risk prediction models could help medical professionals identify more people who are at higher risk and deliver advice and treatment to reduce their risk of future heart attack and strokes."

The authors acknowledged limitations in the study, including that the data is based on populations in high-income countries. Whether this test would be effective in populations worldwide and specifically in low- and middle-income countries is less certain.