Author + information
- Alistair G. Royse, MBBS, MD∗ (, )
- Sandy Clarke-Errey, PhD,
- Anthony P. Brennan, MD,
- Zulfayandi Pawanis, MBiomedSc and
- Colin F. Royse, MBBS, MD
- ↵∗The Royal Melbourne Hospital, The University of Melbourne, PO Box 2135, Melbourne, Victoria, 3050, Australia
We thank Dr. Motekallemi and colleagues for their interest in our paper (1). They are correct to point out that even extensive retrospective propensity score matching (PSM) will not account for all potential variables affecting graft selection. In this study time frame of the 1990s, many of the variables relating to coronary anatomy were not collected. However, the authors are incorrect in asserting that the variables listed are of much greater importance than those used for the PSM and imply invalidity of the results.
Currently, clinicians are fixated on the use of more arterial conduits leading to higher late survival from lower progressive failure relative to saphenous vein grafts (SVG), which have a well-documented pattern of failure. We challenge the reader to consider an alternative: that it is reducing the use of SVG that leads to improved outcome—after all, it is the SVG that is likely to fail.
We direct the reader to a recent publication where this concept was tested in a largescale cohort (2). Of 24,632 PSM patients, with 2.7 ± 1.1 grafts in each group, 1 group with a single SVG had 1.1 ± 0.6 internal mammary artery (IMA) and 0.7 ± 0.8 radial artery (RA)—so-called multiarterial grafting. The comparison group, those having total arterial revascularization, had 1.4 ± 0.7 IMA and 1.4 ± 0.9 RA. The mortality hazard was 1.22 (95% confidence interval: 1.14 to 1.30) with 1 SVG. Similar data were evident when ≥1 SVG was included in 1 arm (2). These results were reported despite coronary anatomy or other considerations referred to by Dr. Motekallemi and colleagues, indicating that these factors were not predominant in the decision making over many years.
Whereas a prospective randomized trial is preferable to a retrospective PSM, it cannot be applied to a historical cohort; and because mortality outcome after surgery requires many years to elapse, PSM analysis is still useful in that it points toward a logic or rationale. A randomized controlled trial may not be ideal either, if it has high crossover as did the recent ART trial (Arterial Revascularisation Trial) (3), or randomization occurs according to a variable that is later discovered not to be the most important in determining outcome.
In our paper (1), we analyzed all-cause mortality against both a conventional operation of left IMA+SVG or to our regional conventional operation of total arterial revascularization. The study findings are broadly consistent with the recent publication on survival with use of SVG (2); and this is consistent with general logic. In the cause of coronary artery bypass grafting failure, we should concentrate our attention on the conduit that is more likely to fail in the long term, rather than the conduit that is more likely to survive.
Please note: The authors have reported that they have no relationships relevant to the contents of this paper to disclose.
- 2019 American College of Cardiology Foundation
- Royse A.G.,
- Brennan A.P.,
- Ou-Young J.,
- Pawanis Z.,
- Canty D.J.,
- Royse C.F.
- Royse A.,
- Pawanis Z.,
- Canty D.,
- et al.
- Taggart D.P.,
- Altman D.G.,
- Gray A.M.,
- et al.