Meta-Analysis Shows Long-Term Cognitive Impairment Is Rare After Undergoing CV Procedures

Deborah Brauser

July 23, 2015

MINNEAPOLIS, MN — A long-term decrease in cognitive function is uncommon after undergoing common CV procedures, a new meta-analysis of 21 studies suggests—but with a few caveats[1].

The systematic review showed no significant differences in cognitive-function scores between those who underwent surgical carotid revascularization vs carotid stenting or angioplasty or between those who did or did not undergo CABG at least 3 months prior.

There were also no differences in scores among most of the patients undergoing various types of CABG. However, one small study (n=64) showed a lower risk of cognitive impairment in those who had on-pump CABG with minimal extracorporeal bypass vs those who underwent conventional extracorporeal bypass (risk ratio [RR] 0.34, 95% CI 0.16–0.73).

Another small study (n=64) showed higher impairment scores at 3 months in participants who underwent transcatheter aortic-valve replacement (TAVR) compared with those who underwent surgical AVR (SAVR) (P=0.04). However, most of the studies had low-to-insufficient strength of evidence, and the latter one was found to have "large selection and outcome measurement biases," report the researchers.

"We found fewer studies than we had hoped comparing more vs less invasive treatments for the same problem," lead author Dr Howard A Fink (Veterans Affairs Health Care System, Minneapolis, MN) told heartwire from Medscape.

"Where we did find studies, there were fewer adverse cognitive effects than we expected, although we were limited by some of the study quality issues and reporting methods used," he added.

Still, the results suggest that "when clinicians are talking about potential risks with patients who are going to go through these procedures, they can be a little reassuring about possible cognitive risks," said Fink.

The findings were published in the July 21, 2015 issue of Annals of Internal Medicine.

Mixed Results for Past Studies

Previous research has suggested a link between cognitive impairment and undergoing CABG, which was "possibly attributable to surgical factors, such as anesthesia and cardiopulmonary bypass," note the investigators. However, more recent trials have suggested that this impairment could be present but not detected before the procedures and/or caused by factors such as age and vascular disease.

Findings have been mixed for studies that examined other types of CV procedures, and very few have assessed long-term cognitive outcomes.

"The general perception has been that there were significant adverse cognitive effects after these procedures. So we wanted to examine if that were true," said Fink.

Researchers assessed data from 17 randomized controlled trials and four prospective cohort studies conducted between 1990 and January 2015. Among all patients, 80% were men and the mean age was 68 years. All of the selected studies included neuropsychological testing of attention, memory, and/or executive functioning.

Cognitive Improvements?

For coronary artery revascularization, the investigators examined one 326-person study that compared patients with CAD who underwent on- or off-pump CABG with those who underwent medical management. They found no between-group differences in any of the neuropsychological tests administered. Interestingly, memory scores actually improved at the 1-year follow-up in both groups, but not at the 6-year follow-up.

Five additional studies compared patients who underwent on- vs off-pump CABG and showed similar results. Both groups had improved memory scores at 1 year and not at 6 years, but there were no significant between-group differences at any time point.

There were also no differences in cognitive scores in the three studies that compared patients who underwent hypothermic CABG with those who underwent normothermic CABG, or in the six studies that compared other types of CABG procedures, including with fentanyl vs propofol, low- or high-dose fentanyl, and hyperbaric vs atmospheric oxygen.

For carotid artery revascularization procedures, researchers examined three studies. One compared cognitive function in patients with carotid stenosis who underwent carotid endarterectomy (CEA) vs those without stenosis who underwent laparoscopic cholecystectomy (control group). The study showed improved scores for the symptomatic CEA vs control group at 3 and 12 months, but not for the asymptomatic CEA group.

The other two studies, which compared CEA with carotid artery stenting and carotid angioplasty, showed no significant differences in mean changes from baseline on neuropsychological scores.

Low Adverse Outcomes

In addition, there were no significant differences in cognitive impairment in those who underwent SAVR or surgical aortic valve-replacement alone or with CABG vs those who underwent CABG only and those who underwent SAVR "under hypothermic and normothermic conditions," report the investigators.

They add that they couldn't find any "eligible studies" that compared ablation with other atrial-fibrillation treatments or medical management in relation to long-term cognition, and no studies that examined PCI in this way.

Overall, the researchers expressed surprise that they found so few eligible comparison studies that examined cognitive outcomes after CV procedures. Still, they add that the results do point to very low treatment-related adverse cognitive outcomes for CABG and between surgical vs endovascular carotid revascularization.

Fink reported that the investigators are now "in the early stages" of developing a research proposal to prospectively assess whether cognitive impairment occurs after patients undergo these procedures.

The study was funded by the Agency for Healthcare Research and Quality (AHRQ). Fink reports having received grants from AHRQ. Disclosures for the coauthors are listed in the article.

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