Senior Cardiac Surgery Patients May Suffer Extended Cognitive Problems
Postoperative delirium a common complications in hospitalized senior citizens over 65; may be key to improve
recovery of cognitive ability
July 5, 2012 - Older patients undergoing cardiac surgery often experience changes in cognitive function, such as memory
problems or an inability to focus, in the days immediately following their operations. While these changes are usually temporary, for unknown
reasons, a significant number of cardiac patients will encounter long-term cognitive problems, lasting as long as a year after their
New research establishes a link
between postoperative delirium and prolonged loss of cognitive function in cardiac surgery patients, according to a report published in the
July 5 issue of The New England Journal of Medicine (NEJM).
Led by investigators at the University of Massachusetts Medical School, Beth Israel Deaconess Medical Center and the
Aging Brain Center at Hebrew SeniorLife, the findings suggest that interventions to prevent delirium in advance of surgery could help cardiac
patients avoid long-term cognitive consequences.
A state of confusion that can develop following illness, infection or surgery, delirium is one of the most common
complications in hospitalized patients over age 65.
"Our findings now suggest that postoperative delirium, once thought of as an acute, transient cognitive disorder, may
have longer-term effects on cognitive function in patients undergoing cardiac surgery," said co-lead author Jane Saczynski, PhD, assistant
professor of medicine at the University of Massachusetts Medical School.
While delirium has been studied quite extensively in other patient populations, including general medical and surgical
patients and orthopedic surgery patients, few studies of delirium have targeted cardiac surgery patients.
"With the aging of the patient population undergoing cardiac surgery and increases in survival after surgery, clinicians
and patients are increasingly concerned with factors associated with quality of life, including cognitive status, as major outcomes of
surgery," the authors write.
"Whether postoperative delirium is associated with prolonged cognitive dysfunction has been unclear."
The researchers followed 225 patients, aged 60 to 90, who underwent either coronary artery bypass grafting (CABG) or
heart valve replacement surgery at Beth Israel Deaconess Medical Center (BIDMC), UMass Memorial Medical Center or the Boston VA Medical
Center, for one year after their surgeries, assessing them for both delirium and cognitive impairment.
"One of the real strengths of our study is that we assessed patients' cognitive function preoperatively and an average of
five times during the year after surgery," said co-lead author Edward Marcantonio, MD, section chief for research in BIDMC's Division of
General Medicine and Primary Care and professor of medicine at Harvard Medical School.
"Previous research had shown an association between postoperative delirium and functional decline in activities of daily
living [such as grooming and dressing, driving, shopping, preparing meals and managing medications and finances.] But, believe it or not, the
one thing that's been most uncertain is the association between delirium and long-term cognitive difficulties.
“This study allowed us to accurately model the course of cognitive function and to compare the rate of recovery among
patients with and without postoperative delirium."
The results showed that compared with patients who did not experience delirium, the 103 patients who developed delirium
after cardiac surgery – 46 percent of the total – experienced a more significant drop in cognitive performance immediately following surgery,
as determined by the Mini-Mental State Examination (MMSE).
They also took significantly longer to recover back to their pre-surgical level of function than did patients who did not
develop delirium. For example, five days after surgery, nearly half of those who did not develop delirium had returned to pre-operative levels
of function while less than 20 percent of those who did develop delirium had returned to pre-operative level of function; six months after
surgery, more than three-quarters of those without delirium had recovered cognitively compared to only 60 percent of those with delirium.
Although patients who developed delirium took longer to recover to their pre-operative levels of cognitive performance,
they continued to improve in the weeks and months after surgery. Cognitive performance reached preoperative levels and stabilized one month
after surgery in patients who did not develop delirium but continued to improve until six months after surgery in those with delirium.
These findings suggest that identifying patients at high risk for delirium prior to surgery and promoting the use of
interventions to prevent delirium in cardiac surgical patients may have substantial benefits. It could improve the recovery rate of cognitive
abilities and enhance functional recovery following surgery.
Further cognitive screening at discharge may also identify patients who require closer, post-operative monitoring or
tailored transitional care to enhance the return of cognitive functions.
"Since patients who experience delirium continue to show improvement in cognitive function six months after surgery,
extending additional rehabilitation services to these patients may have added benefits," said co-senior author Richard N. Jones, ScD, director
of mental health and aging at Hebrew SeniorLife and assistant professor of medicine at Harvard Medical School.
"The findings from this study highlight the clinical importance of the identification of delirium and the potential of
preventive interventions like the Hospital Elder Life Program [HELP]," said co-senior author Sharon K. Inouye, MD, MPH, director of the Aging
Brain Center at Hebrew SeniorLife and professor of medicine at Harvard Medical School.
"Although it is possible to identify patients at high risk for developing delirium and preventive interventions for
delirium exist, these interventions have not been well tested in patients undergoing cardiac surgery. Additional development and testing of
these interventions need to be studied in this patient population to accurately assess the potential benefits for cardiac patients."
"More than half a million heart surgeries are performed each year," said Marcantonio. "Our findings provide important
information that might help doctors design interventions to improve the outcomes of older adults undergoing cardiac surgeries."
Support for this study was provided by grants from
the Harvard Older Americans Independence Center, the National Institute on Aging, the National Heart, Lung, and Blood Institute, and the
National Institute on Aging, and by a National Institutes of Health (NIH) Mid-Career Investigator Award and an NIH Translational Research in
About the University of Massachusetts Medical
The University of Massachusetts Medical School, one
of the fastest growing academic health centers in the country, has built a reputation as a world-class research institution, consistently
producing noteworthy advances in clinical and basic research. The Medical School attracts more than $270 million in research funding annually,
80 percent of which comes from federal funding sources. The mission of the Medical School is to advance the health and well-being of the
people of the commonwealth and the world through pioneering education, research, public service and health care delivery with its clinical
partner, UMass Memorial Health Care. For more information, visit
About Beth Israel Deaconess Medical Center
Beth Israel Deaconess Medical Center is a patient
care, teaching and research affiliate of Harvard Medical School and ranks third in National Institutes of Health funding among independent
hospitals nationwide. BIDMC is a clinical partner of the Joslin Diabetes Center and a research partner of the Dana-Farber/Harvard Cancer
Center. BIDMC is the official hospital of the Boston Red Sox. For more information, visit
About Hebrew SeniorLife
Founded in 1903, Hebrew SeniorLife, an affiliate of
Harvard Medical School, is a non-sectarian, nonprofit organization devoted to innovative research, health care, education and housing that
improves the lives of seniors. Scientists at the Institute for Aging Research seek to transform the human experience of aging by conducting
research that will ensure a life of health, dignity and productivity into advanced age. The Institute for Aging Research carries out rigorous
studies that discover the mechanisms of age-related disease and disability; lead to the prevention, treatment and cure of disease; advance the
standard of care for older people; and inform public decision-making. For more information, visit
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