Review finds little evidence of link between heart procedures and cognitive decline
Physicians can tell older patients that although current data suggest cognitive risks may be small, there is substantial uncertainty about these estimates.
Cognitive decline following regularly performed invasive heart procedures may be uncommon in older adults, a systematic evidence review found, although evidence was limited and quality of the studies was low.
Researchers reviewed 17 randomized controlled trials and 4 cohort studies to evaluate intermediate and long-term cognitive outcomes following the procedures and determine if the associations were modified by procedural and patient characteristics or by procedure-related stroke or transient ischemic attack. They focused on patients 65 years and older. The review appeared in the July 21 Annals of Internal Medicine.
Of the few eligible studies identified, little to no differences in cognitive outcomes between or within treatment groups were found.
One prospective cohort study (n=326) compared on- or off-pump coronary artery bypass grafting (CABG) versus medical management in older adults with catheter-proven coronary artery disease. The CABG and medical groups had small to moderate improvements in memory compared to baseline at 1 year and no changes compared to baseline at 6 years for all neuropsychological tests measured. Further, there were no between-group differences at any follow-up or in change from baseline to any follow-up. Strength of evidence was rated as insufficient by the reviewers because of limitations and the absence of corroborating studies.
The review also found that cognitive function did not differ after the procedure between on- and off-pump CABG (low strength of evidence). Five randomized controlled trials (n=2,349) and 1 prospective cohort study (n=227) compared on- versus off-pump CABG in older adults. On- and off-pump CABG groups had statistically significant within-group improvements compared to baseline in most memory tests at 12 months but not at 6 years and no changes compared to baseline for other neuropsychological tests or global cognitive screening tests. However, there were no statistically significant between-group differences in incident cognitive impairment at 3 to 12 months after surgery (4 trials) and no consistent between-group differences at follow-up or in change from baseline at any time point for any cognitive test reported. Strength of evidence was low because, despite several studies with consistent results, confidence intervals were wide, and all studies had at least a moderate risk of bias, the reviewers found.
One trial reported lower risk for incident cognitive impairment with minimal compared to conventional extracorporeal CABG (risk ratio, 0.34; 95% CI, 0.16 to 0.73; low strength of evidence). Two trials found no difference between surgical carotid revascularization and carotid stenting or angioplasty (low and insufficient strength of evidence, respectively). One cohort study reported increased cognitive decline after transcatheter versus surgical aortic valve replacement but had large selection and outcome measurement biases (insufficient strength of evidence).
In 3 randomized, controlled trials that randomly assigned older adults to hypothermic or normothermic CABG, there were no statistically significant between-group differences in cognitive outcomes, but the strength of evidence was rated as low. One randomized, controlled trial (n=64) randomly assigned older adults to on-pump CABG with conventional extracorporeal bypass versus on-pump CABG with minimal extracorporeal bypass and found patients with minimal extracorporeal bypass performed significantly better at 3 months on all but 1 neuropsychological test and were less likely to have incident cognitive impairment (21% vs. 61%; risk ratio, 0.34; 95% CI, 0.16 to 0.73), but researchers considered the study as having uncertain clinical importance.
“Results suggest that persistent cognitive impairment after the studied cardiovascular procedures may be uncommon or reflect cognitive impairment that was present before the procedure,” the authors wrote. “Although preprocedure cognitive testing could possibly predict subsequent cognitive function, determining whether such screening would improve outcomes was outside the scope of our review. Physicians counseling older patients having the studied cardiovascular procedures should advise that although current data suggest cognitive risks may be small, there is substantial uncertainty about these estimates.”