Reducing infections after heart surgery could save Medicare $441 million per year

Where a patient undergoes heart surgery can significantly affect their risk of infection following the procedure, with some patients facing more than double the risk of others, according to a new Michigan Medicine study.

Researchers estimate that if United States hospitals with higher infection rates for heart surgery patients could achieve outcomes similar to those with the lowest rates, they could annually prevent about 2,600 infections and reduce Medicare spending by $441 million.

The study was funded by the Agency for Healthcare Research and Quality.

The findings are published in The Journal of Thoracic and Cardiovascular Surgery.

"Reducing infections after cardiac surgery is a national opportunity to improve recovery and lower Medicare spending," said co-first author Ahmad M. Hider, M.D., MPhil, a National Clinician Scholar at the University of Michigan Institute for Healthcare Policy and Innovation and a general surgery resident at the University of Colorado.

"Our findings underscore the need to understand why some hospitals achieve better outcomes and how to disseminate best practices across the country."

Large gaps in infection rates after heart surgery

About one in five patients develop an infection in the months following heart surgery, including urinary tract infections, pneumonia and sepsis.

The research team analyzed Medicare claims from nearly 240,000 cardiac surgery procedures performed at 1,000 hospitals between 2018 and 2023.

The researchers could see which patients had been diagnosed with, and treated for, different kinds of infections.

The study found that hospitals with the highest infection rates experienced more than twice as many infections as the best-performing hospitals, even after accounting for differences in patients and procedures.

Hospitals with higher infection rates had higher rates of stroke, readmission and death up to six months after surgery.

These hospitals also generated significantly higher Medicare spending.

Procedures performed at hospitals in the highest infection group were associated with nearly $16,000 more in Medicare spending during the six months after surgery than those performed at hospitals in the lowest infection group.

Using benchmark modeling, the research team estimated that bringing hospitals with average and high infection rates in line with the best-performing hospitals could prevent about 2,600 infections per year.

It could also reduce annual Medicare spending by as much as $441 million, which equates to nearly 12% of the proposed budget for the National Heart, Lung, and Blood Institute for fiscal year 2027.

"By understanding where practice patterns differ, we can better identify what drives the best outcomes and apply those approaches more broadly to provide consistent, high-quality care for every patient," said co-senior author Francis Pagani, M.D., Ph.D., the Otto Gago MD Endowed Professor in Cardiac Surgery at U-M Medical School.

Recovery risks continue after surgery

More than one-quarter of postsurgical infections were identified when patients were readmitted to a different hospital than the one where they underwent surgery.

Researchers say this finding points to another potential factor: fragmented care.

When patients receive follow up treatment across multiple healthcare systems, complications may be harder to prevent, recognize and manage.

A previous study found that better care coordination for patients undergoing coronary artery bypass grafting (CABG, or heart bypass) could save an estimated $130 million annually in hospital readmission costs.

"Our findings further underscore the importance of care coordination across healthcare settings," said co-senior author Donald S. Likosky, Ph.D., the Richard and Norma Sarns Research Professor in Michigan Medicine's Department of Cardiac Surgery.  

"A combination of hospital-based prevention strategies and effective transitions of care throughout the recovery period are needed."

Likosky and Pagani are members of IHPI and of the Frankel Cardiovascular Center.  

University of Michigan undergraduate student Reem Nasser, a member of Michigan Medicine's Undergraduate Research Academy, served as a co-first author on the study.

Additional authors: Chiang-Hua Chang, Ph.D,  Shiwei Zhou, M.D.,  Thomas M. Braun, Ph.D., Robert B. Hawkins, M.D., M.S.,  Geoffrey D. Barnes, M.D., M.Sc., Michael P. Thompson, Ph.D., and Timothy C. Guetterman, Ph.D., all of University of Michigan, and Russell J. Funk, Ph.D., of University of Minnesota.

Funding/Disclosures: This study was supported by the Agency for Healthcare Research and Quality (R01HS029026). The opinions expressed in this manuscript do not reflect those of AHRQ or the US Department of Health and Human Services.

The authors acknowledge the support from the Michigan Society of Thoracic and Cardiovascular Surgeons Quality Collaborative (MSTCVS-QC), as well as Blue Cross and Blue Shield of Michigan and Blue Care Network (BCBSM), which are part of the BCBSM Value Partnerships program.

The content is solely the authors' responsibility and does not represent the official views of the MSTCVS-QC, Blue Cross Blue Shield of Michigan, Blue Care Network, or any of its employees.

Paper cited: “Interhospital variation in 180-day infections and associated Medicare spending after cardiac surgery,” The Journal of Thoracic and Cardiovascular Surgery. DOI: 10.1016/j.jtcvs.2026.07.017