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I read the article by Cavendish et al. (1) with interest. They described their experience with 320 applications of the Symmetry Aortic Connector (St. Jude Medical Inc., St. Paul, Minnesota) in 121 patients. There were 11 (3%) described failures (proximal occlusion or ostial stenoses). They do not, however, describe the sizes used (gray, green, blue, purple), the quality of the conduit, or the quality/size of the distal target in any of the cases. Furthermore, they do not describe the anticoagulation protocol they followed after using this device.
My colleagues and I also have extensive experience with this device. We recognized early in our experience that because this product is composed of nitinol, it should be regarded as an intra-coronary stent. To that end, we routinely anticoagulate on postoperative day 1 with clopidogrel (300 mg) followed by a daily dose of 75 mg for a minimum of 6 weeks (2). We further justify this anticoagulation regimen by the relative state of hypercoagulation we have previously described, which follows off-pump coronary artery bypass surgery (3). Because of variation on conduit size as well as distal runoff, we no longer routinely use the gray (4.5 to 5.0 mm) or green (5.0 to 5.5 mm) connectors but limit our practice to the blue (5.5 to 6.0 mm) and purple (6.0 to 7.0 mm) devices.
The authors do note that the published incidence of saphenous vein graft failure using conventional suture technique at one year is 15%. Their reported incidence of graft occlusion with this Food and Drug Administration-approved product is one-fifth of this value. It is also interesting to note that in those patients with early graft occlusion, the phenomenon occurred in all grafts. This observation may simply represent poor quality conduit, poor distal runoff, hypercoagulation, or all of the above.
We continue to employ the symmetry device in our surgical practice using the aforementioned protocol. There is no doubt that use of the connector avoids the significant manipulation of the ascending thoracic aorta so often associated with catastrophic cerebral vascular accidents.
- American College of Cardiology Foundation