Second Internal Thoracic Artery Versus Radial Artery in Coronary Artery Bypass Grafting: A Long-Term, Propensity Score−Matched Follow-Up Study

Study Questions:

How do the perioperative and late results of using either radial artery or right internal mammary artery as second conduits for multiple arterial revascularization compare?

Methods:

This is a retrospective analysis of patients undergoing primary coronary artery bypass grafting (CABG) for multivessel coronary artery disease on an elective basis. Patients were excluded if they had previous myocardial infarction within 1 week. A total of 1,001 consecutive patients fulfilled the inclusion criteria: 277 underwent bilateral internal mammary artery grafting, while 724 underwent left internal mammary artery, together with radial artery as well. Sixteen different surgeons performed the procedure, with each having at least 6 years of operative experience. The only difference between the surgical strategy was that in 2006, the skeletonization of the internal thoracic artery was performed. The primary endpoint was long-term overall survival and major cardiac and cerebrovascular event (MACCE)-free (myocardial infarction, stroke, cardiac-related death, or repeat revascularization by either percutaneous coronary intervention or CABG) survival. Propensity matching was performed as well to reduce the impact of treatment selection and for comparative analysis.

Results:

In the full, unmatched patient population group, the mean number of bypass grafts was similar between groups. The mean perfusion time and cross-clamp time was longer in the bilateral internal thoracic artery group. Perioperative MACCE occurred in 1.4% of the bilateral internal thoracic artery and in 5.7% of the radial artery group (p = 0.004). Survival in the full unmatched patient population at 5 years was 98.9% in the bilateral internal thoracic group and 93% in the radial artery group (p = 0.054). However, MACCE-free survival at 3 years was 95.9% in the bilateral internal mammary group and 86.4% in the radial artery group (p < 0.01). When analyzing the propensity score–matched patient population, the perioperative MI rate was lower after bilateral internal mammary grafting. Similarly, MACCE events were lower in the bilateral internal mammary group as well. Perioperative mortality was not different between the treatment groups (p = 0.45). Survival 5 years after CABG was 98.9% in the bilateral internal mammary group for the propensity-matched group and 93% in the radial artery group (p = 0.02). Importantly as well in this propensity-matched group, the MACCE-free survival was 95.9% in the bilateral internal thoracic group compared with 82.2% in the radial artery group (p < 0.01).

Conclusions:

This study provides strong evidence for the superiority of a right internal mammary artery as the first second conduit in multiple arterial revascularizations.

Perspective:

This is an important observational study supporting recent randomized trial results assessing the use of the radial artery as a potential alternative second conduit for CABG. Previous studies including those by the RAPS investigators, as well as the VA Cooperative Study, have sent mixed messages regarding the use of the radial artery graft. Although the radial artery is used more frequently than the right internal thoracic artery graft, primarily because of concerns of sternal wound complications, this study provides strong evidence regarding the use of bilateral internal thoracic arteries as a potential second graft. The concerns of deep sternal wound infection are quite real, however, from both a quality of life standpoint as well as from a mortality standpoint. The authors suggest that skeletonization may reduce the risk for sternal infection. In fact, in this study, the rates of sternal dehiscence were similar in both groups. All in all, I believe that this is an important study to consider, particularly when operating on younger patients.

Clinical Topics: Cardiac Surgery, Invasive Cardiovascular Angiography and Intervention, Atherosclerotic Disease (CAD/PAD), Aortic Surgery, Interventions and Coronary Artery Disease

Keywords: Coronary Artery Disease, Myocardial Infarction, Sternum, Stroke, Follow-Up Studies, Brachiocephalic Trunk, Vascular Patency, Radial Artery, Mammary Arteries, Coronary Artery Bypass, Percutaneous Coronary Intervention


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