EDINBURGH, Scotland — Heart attacks can be predicted more than five years before they happen through a simple eye test, according to new research. Unusual patterns of blood vessels in the retina are a sign of coronary artery disease, say scientists.
The study offers hope of identifying patients most at risk during routine examinations at the eye doctor. Healthier lifestyles such as better diets and more exercise would be prescribed, as well as cholesterol-busting statins or other drugs, long before a potential sudden death.
“This would enable doctors to suggest behaviors that could reduce risk, such as giving up smoking and maintaining normal cholesterol and blood pressure,” says lead author Ana Villaplana-Velasco, a PhD student at the University of Edinburgh in Scotland, in a statement.
The retina is a tiny membrane at the back of the eye containing light sensitive cells. They begin deteriorating from middle age.
“We already knew variations in the vasculature of the retina might offer insights into our health,” says Villaplana-Velasco. “Given retinal imaging is a non-invasive technique, we decided to investigate the health benefits we could obtain from these images.”
Eye scan could reveal more than just heart attack risk
The findings are based on over half a million Britons in the UK Biobank, a database containing their medical records and other information.
“First, we studied the branching patterns of the retinal vasculature by calculating a measure named fractal dimension (Df). We found lower Df, simplified vessel branching patterns, is related to coronary artery disease and hence heart attack,” explains Villaplana-Velasco.
The Scottish team then developed a personalized “forecast model” from participants who had suffered a heart attack after collection of their retinal images. It combined Df with traditional clinical factors, such as age, sex, blood pressure, BMI (body mass index) and smoking history.
“Strikingly, we discovered our model was able to better classify participants with low or high heart attack risk when compared with established models that only include demographic data,” says Villaplana-Velasco. “The improvement of our model was even higher if we added a score related to the genetic propensity of heart attack. We wondered if the Df association was influenced by shared biology. So we looked at the genetics of Df and found nine genetic regions driving retinal vascular branching patterns. Four of these regions are known to be involved in cardiovascular disease genetics. In particular, we found these common genetic regions are involved in processes related to heart attack severity and recovery.”
The results also have implications for other life threatening diseases. Variations in the retinal vascular pattern may be signs of an imminent stroke, or diabetic retinopathy where high blood sugar affects the eye. It is possible the back of the eye opens a window into every condition, with each having its own unique profile.
“We would like to investigate this further, as well as undertaking a sex specific analysis. We know females with a higher heart attack or coronary artery disease risk tend to have pronounced retinal vascular deviations when compared to the male population,” adds Villaplana-Velasco. “We would like to repeat our analysis separately in males and females to investigate if a sex-specific model for heart attack completes a better risk classification.”
‘Demonstrates importance of implementing prevention now’
The convincing findings came as a surprise, despite the researchers knowing there was a link between variations and an individual’s state of health.
“There have been multiple attempts to improve coronary artery disease and heart attack risk predictive models by accounting for retinal vascular traits. But these showed no significant improvement when compared with established models,” says Villaplana-Velasco. “In our case, we found the clinical heart attack definition – the diagnostic codes that describe events in medical records – is central to the successful development of predictive models, underpinning the need for developing robust disease definitions in large studies such as UK Biobank. Once we validated our heart attack definition, we found our model worked extremely well.”
In future, a cheap and easy retinal examination may be able to provide enough information to vulnerable people. The average age for a heart attack is 60. The researchers found their model achieved its best predictive performance more than five years before the heart attack happened.
“So the calculation of an individualized risk from those over 50 years old would seem to be appropriate,” says Villaplana-Velasco. “Our work once more shows the importance of comprehensive analysis of data that is routinely collected and its value in the further development of personalized medicine.”
The study is being presented at a meeting of the European Society of Human Genetics in Vienna.
“This study demonstrates the importance of implementing prevention now, and how personalized health is providing us with the tools to do so,” notes conference chair Alexandre Reymond.
Report by South West News Service writer Mark Waghorn