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To the Editor:
We read with great interest the paper by Korkmaz and colleagues,1 in which the authors describe right coronary artery (RCA) revascularization with internal thoracic artery (ITA) segments, using the coronary–coronary bypass grafting (CCBG) technique. We congratulate them for achieving the 2nd-greatest reported series of CCBG surgery (after Nottin and associates2), as well as for their meticulous search of the literature on CCBG.
The selection of an appropriate conduit and surgical technique to bypass a low-grade lesion (50%–60%) of the RCA remains a challenge for cardiac surgeons. We ourselves have considered,3 in theory, the use of the CCBG technique in such circumstances. It was therefore a great pleasure to read that Korkmaz and co-authors have used this approach in 6 patients with low-grade lesions (their Group III). However, we do not understand why, in 4 of those patients, the bypassed lesions were nonsignificant (as little as 20%–25% stenosis). The authors' follow-up arteriograms revealed free ITA grafts that were patent (if slightly narrowed); yet we wonder if Korkmaz and colleagues are truly advocating the revision of guidelines for coronary revascularization, in regard to the grade of coronary artery stenosis that should be bypassed.
Further, there are very few articles in the medical literature that discuss the mid-term angiographic patency of arterial coronary–coronary conduits (CCC). Barboso and Rusticali4 have reported follow-up angiograms in 2 patients (at 3 and 8 years after surgery), which showed patent arterial CCC (free left ITA segments) over distal lesions on the left anterior descending coronary artery (LAD). Both LADs had presented with proximal (grafted with in situ remnants of the left ITA) and distal lesions. We have recently reported a case in which we achieved perfect angiographic patency of a CCC (free left ITA segment) over a single, distal LAD lesion, 3.5 years after surgery.5
Korkmaz and associates calculate their mean time to follow-up angiography for 24 patients (50% of all cases) to be 16.5 ± 7.8 months (7 days to 2 years). This would be a nice contribution to the literature on mid-term angiographic patency follow-up of coronary–coronary arterial conduits incorporated into the right coronary artery system, were these data not misleading. The authors have reported that 14 of their patients underwent follow-up coronary angiography during the 1st postoperative week (7 days = 0.23 month) and that 2 others underwent follow-up angiography in the 2nd postoperative year (these angiograms were performed 13 to 24 months postoperatively). One other patient underwent follow-up angiography at 4 months, and the remaining 7 patients did so during the 1st postoperative year (these angiograms were performed 7 days to 12 months postoperatively). So the properly calculated mean time to follow-up angiography now appears to be only 5.8 ± 7.7 months (or even less). Thus, overall, this report presents only results that show short-term angiographic patency of coronary–coronary ITA conduits used to revascularize the right coronary system.
Because the progression of coronary artery disease at the site of proximal anastomosis of the CCC is of major concern, the authors have chosen the ostium or 1st segment of the RCA as their proximal anastomotic site in 38patients (79.2% of cases): they have correctly observed that at those sites there is almost no progression of the disease in the natural course of arteriosclerosis. In their report of long-term angiographic follow-up data on thattopic (maximum follow-up, 7 years), Nottin and associates2 never observed the progression of coronary disease on a grafted RCA at the site of proximal CCC anastomosis. However, in the subsequent discussion of the Nottin and colleagues2 article, Mills made the interesting point that Nottin's patients who had undergone follow-up angiography after 10 years were found to have RCA disease that had progressed to the ostia in nearly half of those cases (7 out of 15). It is very difficult to decide in retrospect whether these lesions are the consequence of natural progression of the disease or of medial reactivity and thickening promoted by arteriotomy and manipulation at the site of the proximal CCC anastomosis.
In conclusion, we would like to congratulate Dr. Korkmaz's team for their results and for their efforts to include the CCBG procedure in the armamentarium of cardiac surgeons.