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Eur J Cardiothorac Surg 2005;28:510-511
© 2005 Elsevier Science NL
Letter to the Editor |
a Division of Cardiovascular Surgery, St Vincent Mercy Medical Center, 2213 Cherry Street, ACC Bldg, Suite 309, Toledo, OH 43608, USA
b Department of Surgery, Medical College of Ohio, Toledo, OH, USA
c Department of Medicine, Medical College of Ohio, Toledo, OH, USA
Received 9 May 2005; accepted 16 June 2005.
* Corresponding author. Address: Cardiopulmonary Research, St. Vincent Mercy Medical Center, 2213 Cherry Street, ACC Bldg, Suite 309, Toledo, OH 43608, USA. (Email: robert_habib{at}mhsnr.org).
Key Words: Graft failure • Recatheterization • Coronary revascularization • Conduits
We read with great care and interest the recent article by Dr Shah and colleagues in the May 2005 issue of EJCTS [1]. First, we concur with the authors that the in situ right internal thoracic artery (RITA) graft is probably underutilized by surgeons as is implied in their title. The >93% arterial grafting in their re-angiography coronary artery bypass grafting (CABG) series indicates a high quality program that emphasizes arterial grafting. It was noteworthy that, despite their liberal definition of graft failure (
50% stenosis, occlusion or string sign), the authors reported only 47 (or 7%) anastomotic failures out of 679 total grafts in 219 symptomatic patients with ischemia-directed angiography. These excellent graft patency results—at 3-plus years mean follow-up—were generally true for isolated ITA, radial and vein conduits as well as overall. That said, this article also poses important questions that require further elucidation on the authors' part, and seems to make at least one unjustified conclusion.
The reader is not provided with how many of the 219 patients had failed grafts and if any had multiple failed grafts. Yet, one can safely conclude that the ischemia was unrelated to graft failure in at least 172 (or 79%) of the 219 restudied patients. This finding is substantially different from other related recent reports in symptomatic patients—and it is unclear why that would be [2,3]. The low 5% recurrent ischemia restudy rate following CABG with radial (>3 years mean follow-up) may in part result from incomplete capture of re-studied patients and/or a very stringent threshold for ischemia-directed repeat angiography. In either case, this will limit the generalizability of the reported findings. To what extent are the authors satisfied that their re-angiography capture is complete? Next, to put the data in proper perspective, it is critical to provide readers with additional information. What fraction of the 4782 baseline CABG with radial cohort were actual Radial/ITA graft patients (presumably a large majority)? This will help ascertain the true rate of repeat angiography after radial/ITA CABG—since all 219 patients had both radial and ITA grafts. What fraction of the asymptomatic versus symptomatic radial/ITA patients received additional vein grafts? Here, despite the small number of available vein grafts in the present study, it remains of interest to compare radial versus vein patency specifically in the subset of patients that received both these conduits.
We contend that the results reported by Dr Shah and colleagues can reasonably be used to paint a significantly different picture. Specifically, inasmuch as the angiography follow-up for this CABG with radial series is complete, the low ischemia-directed angiography (<2% of patients per year) reported by shah et al. [1] may be the strongest evidence to date in support of a greater role of radial conduits in CABG. Indeed, this conforms to our group's recent report comparing closely matched vein and radial patients (all of whom received left ITA to left anterior descending pedicle graft) [2]. There, we showed that using radial as a second arterial conduit as opposed to vein resulted in improved late survival especially after the third postoperative year [2]—a finding that closely rivals survival following CABG with bilateral ITA grafting [4]. In that same study, it was also shown that for patients receiving both radial and vein conduits (i.e. each patient served as own control), absolute radial graft failure was significantly less than that of vein grafts [2].
Based on all the above, we suggest that the authors' concluding statement that "When additional grafts are required, there is no evidence to suggest that either radial artery or saphenous vein is superior." may not be objectively derived from the presented data. In fact, this conclusion—which is largely based on their multivariable linear mixed model analysis—seems at odds with their own cumulative patency data (Turnbull Method) in Fig. 3 [1]. Given that these results are based on data from a series where radial grafting dominates (53.5%) and vein grafting is exceptionally rare (6.6%), we suggest that: (1) the odds are necessarily stacked against radial, (2) it is reasonable to question whether the results are a consequence of over-modeling, and (3) a more appropriate vein comparison group may be to analyze ischemia-directed angiography results from the vein grafting sub-cohort of the authors' remaining 1674 primary CABGs over that same time period.
References
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