The findings are detailed in a review titled Gut microbiota's role in heart failure, published in 2025 in Heart Failure Reviews.

In heart failure, blood stagnation and swelling in the legs or lungs also affect the intestinal wall, weakening its protective barrier. This allows metabolites produced by gut bacteria to enter the bloodstream more easily, promoting chronic, low-grade inflammation.

“Patients with heart failure often have intestinal dysbiosis, which includes a decrease in the diversity of the microbiota and a loss of bacteria with anti-inflammatory effects, including microorganisms that produce short-chain fatty acids (SCFAs),” said Kamila Florek, study author from the Institute of Heart Diseases.

Multiple factors influence gut microbiota, including genetics, diet, environment, and treatments. As a result, the researchers note, there is no single microbiota profile specific to heart failure patients.

“The relationship between the heart and the gut is not one-sided. Heart failure treatment can alter the gut microbiota, and the microbiota can affect drug metabolism and efficacy,” Florek said.

Certain drugs appear to interact with the microbiota. “Drugs such as ACEIs/ARBs and β-blockers correlate with increased abundance of potentially beneficial butyrate-producing bacteria. Data on SGLT2 inhibitors come mainly from preclinical studies and suggest a shift in the microbiota toward a ‘more favourable’ profile, but their clinical relevance in humans remains as yet unclear,” said Mateusz Sokolski, co-author from the Clinical Department of Heart Transplantation and Mechanical Circulatory Support.

Patients with advanced heart failure, including those undergoing heart transplantation or mechanical circulatory support, represent a special group. In transplant patients, gut microbiota can influence the metabolism of immunosuppressive drugs such as tacrolimus and mycophenolate mofetil. Variations in microbiota composition may affect drug exposure, raising the risk of toxicity or insufficient immunosuppression.

The review also highlights the potential impact of microbiota on immune function and graft rejection. Early data suggest that elevated levels of trimethylamine N-oxide (TMAO), a metabolite produced by gut bacteria, may be linked to faster progression of coronary lesions in grafts and a higher risk of acute cardiac rejection.

The authors caution that while the gut microbiota’s role in heart failure is increasingly documented, there is currently no evidence to support routine microbiota-targeted interventions for all patients. (PAP)

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