Bad gut bacteria could raise risk of premature death for people with heart failure

Poor gut health could increase the risk of dying early or being hospitalized by almost 10% for people with heart failure, and in the first year after being admitted to hospital with heart failure, people are 8% more likely to die or be readmitted if they show signs of an unhealthy gut, according to a study led by researchers at the University of Leicester published in the European Journal of Preventive Cardiology.

The research includes gut microbes in an algorithm that can classify heart failure patients as high-risk, low-risk, or at intermediate risk of death or readmission to hospital. The algorithm takes into account 11 separate factors including people’s age, whether they have diabetes or chronic obstructive pulmonary disease (COPD), the medications they are taking, the number of times people had previously been hospitalized with heart failure, and the severity of their heart failure.

Doctors often use this information to calculate the risk of complications for people with heart failure, but don’t currently tend to take into account their gut microbes. However, there is growing evidence that the helpful and harmful microbes living in our guts, influenced by the foods we eat, can impact heart health, for example by causing inflammation in the body.

The researchers measured several gut-related chemicals in the blood, such as gamma‑butyrobetaine and acetyl-L-carnitine, which tend to rise in people who eat a Western‑style diet high in red meat and eggs.

The team found that people whose blood tests indicated high levels of these chemicals, produced by gut microbes that thrive off this kind of diet, were at higher risk of dying or being hospitalized within a year.

They say the benefits of eating a balanced and varied diet go beyond maintaining a healthy weight and keeping cholesterol in check. Eating foods that feed “good” microbes in the gut could prove to be an effective way of helping the heart for cardiovascular patients.

The result was found in data from 2,071 people, including patients with acute heart failure who attended the University Hospitals in Leicester and a separate group of heart failure patients across 12 European countries.

Patients were tracked for 12 months after being admitted to hospital with heart failure. The risk of being hospitalized for heart failure or dying from any cause—not just heart failure—was 8% higher for people with an unhealthy gut.

The researchers’ algorithm, which was developed using data from the same patients, was found to be highly accurate in determining people’s risk. The survival rate among people classed as low risk was about twice as high as among the group classed as high risk.

The algorithm was found to be similarly accurate when categorizing patients compared to risk calculators which doctors already use. These help medical professionals to plan people’s care by identifying which patients need the most intensive treatment.

But calculators typically only predict people’s risk up to a maximum of 30 days, while the current algorithm can estimate risk for up to a year.

Heart failure is a debilitating condition where your heart cannot pump blood around your body as well as it should, causing symptoms like fatigue, shortness of breath, and swelling in the legs.

Previous evidence has found poor gut health is commonly seen in people with advanced heart failure.

Professor Toru Suzuki, professor of cardiovascular medicine at the University of Leicester, who led the study, said, “This study provides clear further evidence of the powerful influence the gut microbiome has over cardiovascular health. Our research has now found a way to harness that power, improving the tools doctors use to predict risk when treating seriously ill patients.

“We hope the new calculator can be adopted in management guidelines for heart failure within the next few years, giving doctors the ability to better support their patients and save lives.”

Professor Bryan Williams, chief scientific and medical officer at the British Heart Foundation, said, “Research continues to reveal a potential link between gut health and heart health. This study evaluated whether the assessment of gut health might help predict patient outcomes if they have heart failure.

“It also raises the intriguing question as to whether taking action to improve gut health might help improve the outcome of patients with heart failure. This would require further research.”