Rebecca F. Gottesman, M.D., of the Johns Hopkins University School of Medicine, Baltimore, and colleagues assessed 15 patients age 57 to 81 years undergoing coronary artery bypass graft (CABG) operations who were believed to be at high risk for having a stroke following surgery. All patients were given cognitive tests before and three to five days after surgery. Their blood pressure was taken before and during the operation and the mean arterial blood pressure (MAP) was measured. Thirteen of the patients also underwent MRI of the brain following surgery.

All of the participants had a decrease in MAP during surgery compared with their MAP before surgery. Those whose MAP decreased by 27 millimetres of mercury or more had an average decrease in score on the Mini-Mental State Examination, one of the cognitive tests, of 1.4 points, out of a maximum of 30 points. After one individual was excluded from the analysis, those who had a MAP decrease of less than 27 millimeters of mercury increased their scores by an average of one point. Individuals with high MAP before surgery also were more likely to have a decreased cognitive score.

Six of the 13 individuals who underwent MRI had findings in the brain consistent with acute stroke. Because the number of participants was small, it was difficult to analyse this information, the authors note. However, patients with a drop in MAP greater than 27 millimetres of mercury were 2.7 times as likely to have such a lesion as those whose MAP decreased by a smaller amount.

“Our preliminary data from a small group of subjects suggest that a substantial decrease in MAP from a patient’s baseline may be a risk factor for short-term cognitive dysfunction,” the authors conclude.

MEDICA.de; Source: JAMA and Archives Journals