Eur J Cardiothorac Surg 2008;34:1269-1270. doi:10.1016/j.ejcts.2008.08.026
Copyright © 2008, European Association for Cardio-thoracic Surgery. Published by Elsevier. All rights reserved.
Radial artery versus saphenous vein as a second coronary bypass conduit in septuagenarians
Anoar Zacharias,
Robert H. Habib*
Cardiovascular and Pulmonary Research, Yvonne Viens, SGM, Research Institute, St. Vincent Mercy Medical Center, 2222 Cherry Street, MOB2 Building, Suite 1250, Toledo, OH, 43608, United States
Received 15 July 2008;
accepted 27 August 2008.
* Corresponding author. Tel.: +1 419 2514998; fax: +1 419 2510230. (Email: Robert_Habib{at}mhsnr.org).
Key Words: Survival • CABG • Arterial grafts • Kaplan–Meier
The recent article by Hayward and colleagues [1] reported mid-to-late RAPCO trial survival in septuagenarians. They found that patients who receive an internal-thoracic artery to the left anterior descending (LITA-LAD) had similar 10-year survival when the next best target is grafted with radial artery (RA) or saphenous vein (SVG). This result diverges from those in a related retrospective propensity-matched analysis where RA and SVG were compared as the second conduit of choice in LITA-LAD CABG [2]. There, RA was associated with significantly improved 6-year survival particularly after the third postoperative year, and this was true for both the younger and older sub-cohorts [2]. These discordant findings [1,2] may derive from more restrictive inclusion/exclusion criteria of the RAPCO trial [1] compared to a large all-inclusive retrospective series. We wish to communicate a number of observations that may elucidate further these divergent findings:
- (I) The RA and SVG PAPCO groups’ number of grafts was similar at 3.2 and 3.3 grafts [1] yet no information on arterial versus venous use for the third and fourth grafts is given. The authors are leaders of RA use and given their propensity to maximize arterial grafts, it is likely that the total arterial grafts were similar for the SVG and RA groups. If true, this may explain the similar survival data. Multiple groups have reported that increasing arterial grafts results in improved survival.
- (II) It is safe to assume that most to all patients had multi-vessel coronary disease. But, it is conceivable that the two- versus three-vessel disease may have differed for the study groups (data not provided), providing this serves as a surrogate measure of completeness of revascularization, a well-accepted determinant of mid-to-late CABG outcomes.
- (III) The authors’ primary criterion for the ‘next best target other than the LAD’ for study conduit placement was the coronary target vessel size. Hence, because of the usual greater probability of right coronary dominance, it is quite likely that a disproportionately higher number of the study conduits (SVG or RA) may have been used to revascularize right coronary artery (RCA) targets as opposed to LAD diagonals or branches of the circumflex system. Ironically, multiple authors have reported that RA graft patency is generally worse when placed to the RCA even when
70% stenosis is present (e.g., [2,3]). Critically, this considered with point II above, puts forth the possibility that the SVG group may have had more radial grafts placed to targets where it is associated with superior patency when compared to the RA group. Such a scenario has significant implications on the survival comparison, and a more complete description of the overall RA and SVG graft placement is needed to allow a better interpretation of this study’s findings.
- (IV) We noted that RA had a larger number of protocol breaches compared to SVG (9 vs 2) that are uncorrected given the intent-to-treat analysis. Given the small sample size and low overall adverse events rate, it is helpful if a description of these events in breaches (if any) is provided, or if a complementary comparison with breaches removed is shown.
We congratulate the authors on this thought-provoking paper and look forward to their response.
References
- Hayward PA, Hare DL, Gordon I, Buxton BF. Effect of radial artery or saphenous vein conduit for the second graft on 6-year clinical outcome after coronary artery bypass grafting. Results of a randomized trial. Eur J Cardiothorac Surg 2008;34(1):113-117.[Abstract/Free Full Text]
- Zacharias A, Habib RH, Schwann TA, Riordan CJ, Durham SJ, Shah A. Improved survival with radial artery versus vein conduits in coronary bypass surgery with left internal thoracic artery to left anterior descending artery grafting. Circulation 2004;109:1489-1496.[Abstract/Free Full Text]
- Maniar HS, Sundt TM, Barner HB, Prasad SM, Peterson L, Absi T, Moustakidis P. Effect of target stenosis and location on radial artery graft patency. J Thorac Cardiovasc Surg 2002;123:45-52.[Abstract/Free Full Text]
