July 6, 2012 (Prague, Czech Republic) — Octogenarians do not experience more major neurological complications after cardiopulmonary bypass compared with younger patients, but risk factors differ between the 2 groups, a new study suggests.

"Preoperative anemia appears to be the most significant risk factor for neurological complications among the over-80 population, whereas peripheral vascular disease predicts complications for the younger set," said lead author Angel Guerrero, MD, from the Department of Neurology at University Hospital in Valladolid, Spain.

An increasing number of very old patients are undergoing cardiac surgery, and advancing age has been identified as a risk factor for stroke or other neurological complications after cardiopulmonary bypass (CPB).

In this study, the authors set out to identify risk factors for major neurological complications, and although they identified different underlying risk factors for patients younger or older than 80 years, they did not find a significantly higher rate of complications for the older group.

These findings were reported here at the 22nd Meeting of the European Neurological Society.

Underlying Factors

Investigators matched 375 consecutive patients older than 80 years (group A) undergoing cardiac surgery with CPB between 2000 and 2011 with 427 patients younger than 80 years (group B). Matching was based on gender, type of surgery, and comorbidity. They retrospectively evaluated risk factors for major neurological complications after surgery.

The groups were well matched for clinical characteristics, preoperative risk factors, and procedure type for most parameters, except that group A was significantly older (mean, 81.6 vs 66.6 years; P < .001), had fewer previous myocardial infarctions (18.4% vs 24.6%; P = .034), had more left main coronary artery disease (19.3% vs 11.1%; P = .001), had more urgent surgery (8.3% vs 6.3%; P = .047), and had more bioprosthetic and fewer mechanical valve implants (both P < .001). Group A also had slightly more adjusted EuroSCORE I (low) risk cardiac surgery patients but longer hospital stays (both P < .001).

"The percentage of neurological complications was more or less the same in both groups — a bit more than 6% [6.7%] in octogenarians and 5.9% in people under 80, and we also noticed that dividing the neurological complications into 5 classical groups — stroke, transient ischemic attack, coma, acute confusional syndrome, and seizures — there were really no differences among both groups apart from the [higher] percentage of acute confusional syndrome among octogenarian people," Dr. Guerrero told Medscape Medical News.

Although the older patients experienced a greater than 3-fold higher rate of postoperative acute confusional syndrome (1.3%) vs younger ones (0.4%), the difference was not statistically significant (P = .35).

Octogenarians experienced a higher mortality rate (13.6%) compared with younger patients (9.2%; P = .046). For both older and younger patients, lengths of intensive care unit stay and total hospital stay were longer if neurological complications occurred, but no significant differences were noted according to age.

In a multivariate analysis, investigators identified 2 risk factors for postoperative major neurological complications in the older cohort—preoperative anemia (relative risk [RR], 2.70; 95% confidence interval [CI], 1.13 - 6.43; P < .0037), defined as a hemoglobin level less than 12 g/dL for women or 13 g/dL for men, or less than 2 standard deviations below the reference population mean level, and mitral valve vs other types of surgery (P = .031).

For the younger cohort, preoperative peripheral vascular disease emerged as the only risk factor and more than tripled the risk of major neurological complications (RR, 3.72; 95% CI, 1.43 - 9.64; P < .007).

These study results support the idea that age in itself is not a contraindication to cardiac surgery regarding major neurological complications.

Colleagues in the cardiac surgery department at Dr. Guerrero's institution suggest that these types of biological factors "are the real problem," so cardiac surgery can be offered to patients over 80 as long as "you do it properly, with a good set of indications and in a good biological status."

Dr. Guerrero added that he and his colleagues have not studied cognitive function in octogenarians postoperatively, "but we aim to prospectively look for cognitive deficits in this kind of patient from now on," using a preoperative and postoperative battery of neuropsychological tests.

Comparative Data

Stanley Iyadurai, MD, PhD, assistant professor of neurology at St. Louis University in Missouri, commented to Medscape Medical News that the study had a good data set based on the substantial number of patients, but he questioned whether the data are generalizable.

"I'm not sure how [these] data would look in the US, for example," he said. "I'm surprised that the octogenarians had the same complication rate [as] the ones less than 80 as a group. Comparative data would be extremely helpful."

Dr. Iyadurai said it was interesting that one of the risk factors for octogenarians was anemia. "I would have assumed hypoxemia, but that may be secondary to anemia as well."

Dr. Iyadurai said that anemia may be a sign of other underlying problems, so simply correcting the anemia before surgery may not eliminate the risk of older patients' developing major neurological complications.

"They may have chronic issues leading to that anemia — B12 deficiency [and] so many other reasons. I don't think we can say whether correcting the anemia would be helpful," he suggested. "Delirium, which is the one that they're referring to as the change in mental status immediately after surgery — that is expected. Acute confusional syndrome is what they call it. It's 3-fold [higher] in octogenarians. That is probably true."

Neither Dr. Guerrero nor Dr. Iyadurai has disclosed any relevant financial relationships.

22nd Meeting of the European Neurological Society: Abstract P-431. Presented June 10, 2012.


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