Gut bacteria may predict heart failure after heart attacks

Published: 28 September 2025

A New Zealand study will explore whether gut bacteria can predict heart failure risk after a heart attack, potentially leading to earlier diagnosis, personalised treatment, and new ways to protect heart health.

A researcher from the University of Otago has received funding from the Heart Foundation to explore whether bacteria from the gut could be used to identify heart attack patients most at risk of developing heart failure, before symptoms appear.

Dr Sarah Appleby has been studying the trillions of bacteria that live in our gut, called the gut microbiome. Her previous research found that after a heart attack, the gut barrier can weaken, causing a condition called “leaky gut”, allowing bacterial DNA to seep into the bloodstream and trigger harmful inflammation that may worsen heart health. 

Now a new pilot study will investigate whether certain bacteria and their byproducts can be used to predict which heart attack patients are more likely to develop heart failure within a year.

Sarah says her research offers a fresh perspective on heart failure, with few studies worldwide exploring the role of gut bacterial DNA. 

If successful, it could lead to earlier diagnosis, better risk prediction, more personalised treatment, and improved gut health to help protect the heart. 

“We want to see if any of these bacteria in our stomach that are escaping into the bloodstream can contribute to the progression of heart failure after a heart attack. If it is, we want to work out how we can stop that,” Sarah says.

How the research will work

Researchers will compare 100 heart attack patients who developed heart failure within a year with 100 patients who didn’t. 

They will analyse the bacterial DNA and byproducts in their blood in the hope of identifying warning signs and new treatment targets.

“In an ideal world, we want to find clear differences in gut bacteria between those who develop heart failure and those who don’t – such as having more harmful bacteria or fewer beneficial ones.

“We hope to identify biomarkers which will allow us to detect heart attack patients that are more at risk of going on to develop heart failure. It opens the door to new treatment options by targeting and modifying specific gut bacteria.”

“If we can identify who’s at risk earlier, we can intervene sooner and more effectively,” she says.

How gut health could impact heart failure in New Zealand

Heart failure is a significant issue in New Zealand, particularly following a heart attack, with approximately one in five heart attack survivors developing heart failure within five years.                

People who have had a heart attack are six times more likely to experience a cardiovascular event within two years, including heart failure, Sarah says. 

Sarah hopes the research could lead to new treatments that strengthen the gut and balance bacteria, areas current therapies don’t address. 

The findings could also shape clinical guidelines by introducing gut microbiome blood tests into routine post-heart attack care.  

It could one day impact public health strategies that promote gut health as a modifiable risk factor for cardiovascular disease, through diet, probiotics and targeted therapies.  

Heart Foundation Medical Director Dr Gerry Devlin says the link between gut health and heart health is becoming more widely appreciated and it is exciting to see New Zealand researchers contributing to our understanding of this.