Summary: A population-based study finds that older adults who undergo major heart surgery show no substantial long-term memory decline compared with those who receive less invasive catheter-based procedures.
Source: Elsevier
A new analysis published in The Annals of Thoracic Surgery reports that memory changes after major heart surgery are minimal when compared with changes following cardiac catheterization, a far less invasive procedure.
“It was reassuring to find only small differences in cognitive decline between the two procedures, even though one is major open-heart surgery and the other is minimally invasive,” said Elizabeth Whitlock, MD, of the University of California, San Francisco.
The research team used data from the Health and Retirement Study (HRS), a large, federally funded, longitudinal study of older adults in the United States. From 2000 to 2014, 3,105 HRS participants who reported either heart surgery or cardiac catheterization were included. The HRS collects biennial information on health, cognition, demographics, and quality of life, and many participants complete brief objective memory tests every two years.
Cardiac catheterization is a catheter-based procedure commonly used for diagnosis and for placing coronary stents to treat coronary artery disease. The investigators divided participants aged 65 and older into two groups: 1,921 people (62 percent) who reported catheterization and 1,184 people (38 percent) who reported heart surgery. The team compared pre-procedure and post-procedure composite memory scores, with follow-up extending up to two years after the procedure.
After adjusting for multiple factors, the authors found no meaningful additional memory decline associated with heart surgery. The estimated difference in memory change between surgery and catheterization was −0.021 memory units, a magnitude the authors equate to about 4.6 months of normative cognitive aging. For a typical 75-year-old, that difference corresponded to a negligible 0.26 percent increase in the likelihood of losing the ability to manage finances independently and a 0.19 percent increase in the likelihood of losing the ability to manage medications independently.
“Previous reports and anecdotes have suggested significant cognitive decline after heart operations, but our results were different,” Dr. Whitlock noted. “One reason may be that we measured cognition up to two years after the procedure, allowing time for recovery and improvement.”
The study design avoided several common sources of bias. Most participants completed a cognitive assessment well before the reported procedure and then again after a substantial recovery period, minimizing the influence of short-term factors such as preoperative anxiety, postoperative pain, opioid use, delirium, sleep disruption, hospital-related stress, or transient infections. Importantly, the comparison was between patients who all had heart disease, rather than between heart surgery patients and healthy people without heart disease, which more fairly isolates the effect of the treatment itself from the impacts of underlying cardiovascular illness.
“Because the presence of serious heart disease likely affects cognition on its own, comparing surgical patients with healthy people without heart disease can overstate any surgery-related cognitive decline,” Dr. Whitlock explained.
The American Heart Association estimates that tens of millions of Americans live with cardiovascular disease and that millions undergo heart operations or related procedures each year. Coronary artery bypass grafting (CABG) is one of the most common and effective cardiac surgeries. Although CABG is generally safe, postoperative cognitive decline (POCD)—a temporary or persistent reduction in memory and thinking skills—has been frequently reported, particularly among older adults.
Researchers emphasize that multiple mechanisms may explain transient POCD after major surgery: small strokes during the procedure, inflammation from tissue trauma, effects of pain medications, disrupted sleep, delirium, infection, or physical inactivity. Because many of these contributors are temporary, cognitive function often improves as they resolve, which supports the value of measuring cognition over a longer recovery window.
“Most of the factors that could cause short-term cognitive decline after surgery are reversible,” Dr. Whitlock said. “That’s why assessing memory up to two years post-procedure offers a clearer view of whether cardiac surgery has a lasting population-level effect on cognition.”
Funding: Supported by the National Institute of General Medical Sciences, the National Institute on Aging (both part of the National Institutes of Health), and the Foundation for Anesthesia Education and Research.
Source: Jennifer Bagley, Elsevier. Publisher: NeuroscienceNews.com.
Image source: Public domain image provided by NeuroscienceNews.com.
Original research: “Cognitive Change After Cardiac Surgery Versus Cardiac Catheterization: A Population-Based Study” by Elizabeth L. Whitlock, MD, MSc, L. Grisell Diaz-Ramirez, MS, Alexander K. Smith, MD, MPH, W. John Boscardin, PhD, Michael S. Avidan, MBBCh, and M. Maria Glymour, ScD, MS. Published in The Annals of Thoracic Surgery on December 17, 2018. DOI: 10.1016/j.athoracsur.2018.10.021.
Elsevier. Brain Health Not Affected by Major Heart Surgery. NeuroscienceNews. December 18, 2018.
Abstract
Cognitive Change After Cardiac Surgery Versus Cardiac Catheterization: A Population-Based Study
Background: Concerns exist that cardiac surgery may harm cognition, but population-based studies with presurgery data are limited. Using the Health and Retirement Study, investigators compared memory change after participant-reported cardiac catheterization versus cardiac surgery.
Methods: Community-dwelling adults aged 65 and older who reported cardiac catheterization or “heart surgery” in the HRS between 2000 and 2014 were included. The index procedure may have occurred up to two years prior to the survey. The team modeled change from preprocedure to postprocedure in a composite memory score derived from objective tests, using linear mixed effects models; subjective memory decline was modeled with logistic regression. Predicted memory change was translated into potential impacts on the ability to manage medications and finances independently to quantify clinical relevance.
Results: Among 3,105 participants, 1,921 underwent catheterization and 1,184 underwent operation. After adjustment, memory change was similar between groups (difference −0.021 memory units; 95% CI: −0.046 to 0.005; p = 0.12). If causal, this point estimate would correspond to a 0.26% absolute decrease in the ability to manage finances and a 0.19% decrease for managing medications, roughly equivalent to 4.6 additional months of cognitive aging. Surgery was not associated with subjective memory decline (adjusted odds ratio 0.93; 95% CI: 0.74 to 1.18).
Conclusions: In this large, community-based cohort of older adults with heart disease, memory declines following heart surgery and cardiac catheterization were similar. Any intermediate-term adverse cognitive effects of cardiac surgery at the population level are likely to be subtle.