Ann Thorac Surg 2005;79:1462
© 2005 The Society of Thoracic Surgeons
Correspondence
Do Off-Pump Surgical Procedures Really Improve Memory? Reply
Jeffrey D. Lee, MD,
Shay J. Lee, MD,
William T. Tsushima, PhD,
William T. Lau, BS,
David Johnson, PhD,
Helen Petrovitch, MD,
Collin R. Dang, MD
Department of Surgery, University of Hawaii School of Medicine, 1329 Lusitana St, Suite 109, Honolulu, HI 96813, USA
jdl{at}heartsurgery-hawaii.com
To the Editor:
We appreciate the thoughtful comments of Dr Selnes. It is correct that Table 3 in our study [1] does not indicate that the Rey Auditory Verbal Learning Test (RAVLT) score for the patients undergoing coronary artery bypass grafting with cardiopulmonary bypass (CABG group) changed over time, and this could mean the CABG patients were no worse off regarding neurological morbidity. However, statistically speaking, the statements in the article are correct. In fact, when comparing the CABG and off-pump coronary artery bypass (OPCAB) groups preoperatively, the means, although different, were not significantly different (p 
0.05). The question lies in explaining why there was significant improvement in the OPCAB group RAVLT score.
We were careful in this article about making suggestions as to why that finding might be so. The reason for this caution has to do with the fact that some, but not all, tests showed a similar improvement in neurocognitive functioning in the OPCAB group. (Most of them showed no significant difference.) This may have to do with the relatively small sample size of this study. Dr Selnes is correct in recommending parsimony and caution in interpreting these findings, and the suggestion of an alternative explanation is appreciated.
We believe that the findings of this randomized, prospective study lend support to the hypothesis that OPCAB may be less injurious to the neurological system. The 97% difference in cerebral microemboli between groups (575 ± 278.5, CABG group, versus 16 ± 19.5, OPCAB group) and the evidence of completely preserved brain perfusion in the OPCAB group are significant. Markedly reduced cerebral perfusion in the CABG group, in the areas of the bilateral occipital and cerebellar lobes, precunei, thalami, and left temporal lobe (p 0.01) as seen on technetium 99m–labeled HMPAO (hexamethylpropylenzamine oxime) whole-brain single photon emission computed tomographic scanning, provides further objective evidence supporting this hypothesis. We believe that these preliminary findings should be tested in further studies.
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References
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- Lee JD, Lee SJ, Tsushima WT, et al. Benefits of off-pump bypass on neurologic and clinical morbidity: a prospective randomized trial. Ann Thorac Surg. 2003;76:18–26[Abstract/Free Full Text]
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