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Eur J Cardiothorac Surg 2005;28:511-512
© 2005 Elsevier Science NL

Letter to the Editor

Reply to Zacharias et al.

^a Department of Cardiac Surgery, Austin Hospital, Studley Road, Heidelberg, Melbourne, Vic. 3084, Australia
^b Statistical Consulting Centre, University of Melbourne, Parkville, Vic., Australia

Received 15 June 2005; accepted 16 June 2005.

^* Corresponding author. Tel.: +61 3 9496 5453; fax: +61 3 9429 6220. (Email: brian.buxton{at}austin.org.au).

Key Words: Coronary artery bypass grafting (CABG) • Ischemia • Patency

We find much to agree with the comments of Zacharias et al. in the Letter to the Editor. Our differences are largely a matter of interpretation.

Regarding multiple grafts: 50 subjects had two grafts, 106 had three, 51 had four, 10 had five and one had six. There were 180 patients (82%) who did not have a graft failure detected; 32 had one failed graft, six had two, and one had three.

The relationship between recurrent ischemia and graft failure is complex. Ischemia may result from extension of native vessel disease, graft failure, or both. Furthermore, patients who were re-studied for symptoms or evidence of ischemia include those with ischemia and those who had diagnostic angiography, some of whom did not have ischemia. Therefore, the high percentage of patients who were not found to have graft failure may be the result of a low graft failure rate, a relatively high progression rate of native vessel disease or inclusion of a high number with negative diagnostic angiograms.

A comparison of RA versus SV patency in patients who received both conduits is in Table 3 [1], which shows an odds ratio of 1.1 for graft failure, comparing SV to RA. There were 39 such subjects; five had one SV graft failure, six had one RA failure, and the other 28 had no failures. This finding is quite close to the odds ratio arising out of the multivariable model, which adjusts for target artery and coronary stenosis. Due to the small number of vein graft patients, the 95% confidence interval is consequentially wide; Zacharias's and our results are not fundamentally in contradiction.

For survival or patency following CABG, a definitive answer can only be provided by randomized trials. We are conducting such a trial and we will be able to contribute unbiased information on these questions when the follow-up is sufficiently mature [2]. In a recent publication, The Radial Artery Patency Study [3] compared re-angiographic patency of 440 patients who had both a RA and a SV graft in the first 12 months following surgery. The RAs had a lower total occlusion rate compared with the SV, but when those with the string sign (a functional occlusion) were added, the results were almost identical, with a 15% early failure for both grafts.

The cumulative patency data in Fig. 3.1 [1] does not adjust for other explanatory variables, so the curves may give a different perspective than the multivariable model. Nonetheless, the results are consistent qualitatively. Finally, it is not clear why the mere dominance of RA grafting in our series would lead to the odds being ‘necessarily stacked against radial’.

Zacharias quotes the concluding sentence of our abstract; we prefer the form in the conclusion of the paper itself, which more appropriately restricts the finding to the present study, which does not, in fact, offer evidence of a difference between RA and SV graft. We thank Zacharias et al. for their thoughtful consideration of our work and look forward to clearer evidence emerging through larger data sets, longer follow-up and randomized trials.

References

1. Shah P, Bui K, Blackmore S, Gordon I, Hare D, Fuller J, Seevanayagam S. Buxton BF. Has the in-situ right internal thoracic artery been overlooked? An angiographic study of the radial artery, internal thoracic arteries and saphenous vein graft patencies in symptomatic patients. Eur J Cardiovasc Surg 2005;27(5):870-875.
2. Buxton BF, Raman JS, Ruengsakulrach P, Gordon I, Rosalion A, Bellomo R, Horrigan M, Hare D. Radial artery patency and clinical outcomes - 5-year interim results of a randomized trial. J Thorac Cardiovasc Surg. 2003;125(6):1363-1370.[Abstract/Free Full Text]
3. Desai ND, Cohen EA, Naylor CD, Fremes SE. A randomized comparison of radial-artery and saphenous-vein coronary bypass grafts: N Engl J Med. Desai ND; 2004pp. 25;351(22):2262–64.

This Article Full Text (PDF) 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 Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): Brian F. Buxton Permission Requests Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Buxton, B. F. Articles by Gordon, I. Search for Related Content PubMed Articles by Buxton, B. F. Articles by Gordon, I. Related Collections Cardiac - other Coronary disease Great vessels