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Ann Thorac Surg 1996;62:1243-1244
© 1996 The Society of Thoracic Surgeons

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Correspondence

Coenzyme Q10 Treatment May Be Protective During Coronary Artery Bypass Operations

Department of Medicine Cardiology B, Rigshospitalet, National University Hospital, Blegdamsvej 9, Dk-2100 Copenhagen Ø, Denmark.

To the Editor:

It is certainly misleading to the readers of The Annals of Thoracic Surgery to be presented the conclusions from a recently published study by Taggart and associates [1] on possible prophylaxis from coenzyme Q10 (CoQ10) in relation to coronary artery bypass grafting. Taggart and associates stated in the abstract, "The magnitude of increases in cardiac troponin T was greater in the CoQ10-supplemented group ... ". The two study-groups are described as well-matched, which is—unfortunately—also the case with respect to the preoperative levels of the test treatment (CoQ10) in plasma.

It is a considerable limitation that the basic plasma levels (before supplementation with CoQ10 or placebo) are lacking. The immediate preoperative level of CoQ10 is 2.35 ± 0.27 µg/mL in the so-called placebo group, a figure that is very high, and not lower than the level in the CoQ10 group: 2.01 ± 0.18 µg/mL. Both levels are significantly higher than the ordinary level in plasma, which is around 0.6 to 1.0 µg/mL in individuals (normal individuals and patients with ischemic heart disease) not supplemented orally with CoQ10 [2, 3]. The levels in both study groups are in the expected range that is generally achieved from oral CoQ10 supplementation at 100 to 200 mg/day (around 2 µg/mL) using the capsules tested in the present study [4].

In fact, Taggart and associates have shown a tendency toward lower troponin T release in the study group with the highest (at least in the figures) preoperative CoQ10 level. More appropriately, Taggart and associates might have concluded from their findings the following: High plasma CoQ10 stores in patients before coronary artery bypass grafting may protect the myocardium during ischemia and reperfusion, and may prove to be correlated with a lower degree of myocardial damage (if the study had been carried out with a larger patient population).

References

1. Taggart DP, Jenkins M, Hooper J, et al. Effects of short-term supplementation with coenzyme Q10 on myocardial protection during cardiac operations. Ann Thorac Surg 1996;61:829–33.[Abstract/Free Full Text]
2. Hofman-Bang C, Rehnquist N, Swedberg K, Wiklund I, Åström H, for the Q10 study group. Coenzyme as an adjunctive in the treatment of chronic congestive heart failure. J Cardiac Failure 1995;1:101–7.[Medline]
3. Kamikawa T, Kobayashi A, Yamashita T, Hayashi H, Yamazaki N. Effects of coenzyme Q10 on exercise tolerance in chronic stable angina pectoris. Am J Cardiol 1985;56:247–51.[Medline]
4. Folkers K, Moesgaard S, Morita M. A one year bioavailability study of coenzyme Q10 with 3 months withdrawal period. Molec Aspects Med 1994;15:s281–5.

Reply

Oxford Heart Centre, John Radcliffe Hospital, Headington, Oxford OX3 9DU England

To the Editor:

I thank Dr Mortensen for his comments.

1. Doctor Mortensen suggests that the statement in our abstract "The magnitude of increases in cardiac troponin T was greater in the CoQ10-supplemented group, reaching marginal overall statistical significance (p = 0.06)" is misleading. This is, however, simply a statement of fact.
   
2. Doctor Mortensen states that the lack of preoperative plasma levels of CoQ10 is a considerable limitation of our study. We accept that although these data would have provided useful additional information, they would not have altered the basic question we posed (ie, does short-term oral supplementation with large doses of CoQ10 improve myocardial protection?) nor our conclusions. Our assumption that the baseline level of CoQ10 would be similar in the two groups was, in any case, reasonable.
   
3. It is not clear why the plasma CoQ10 levels should be so relatively high in our control patients. The plasma levels of CoQ10 quoted in Dr Mortensen's references 3 and 4 are respectively based on 12 Japanese patients and 21 healthy subjects and may not, therefore, be comparable with the levels in British patients taking various medications that might alter plasma CoQ10 levels.
   
4. Doctor Mortensen's last paragraph does not appear to be logical. Our results clearly show that although there was no significant difference in the preoperative levels of CoQ10, the magnitude of the postoperative decrease in plasma CoQ10 levels was attenuated in the supplemented group. Nevertheless, the CoQ10-supplemented group showed greater increases in creatine kinase-MB, myoglobin, and cardiac troponin T levels, which was of marginal statistical significance (p = 0.06) for the latter. If similar findings were observed in an even larger population this would increase the statistical certainty of our findings.
   

This Article Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): David P. Taggart Permission Requests Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Mortensen, S. A. Articles by Taggart, D. P. Search for Related Content PubMed PubMed Citation Articles by Mortensen, S. A. Articles by Taggart, D. P.