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Making the case for CABG using bilateral thoracic arteries

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All bilateral artery configurations equal

The take-home message of the study by Dr. Magruder and colleagues is that using bilateral internal thoracic arteries (BITA) is more important than the specific configuration, Saswata Deb, MD, BSc, and Stephen E. Fremes, MD, MSc, BSc, of the University of Toronto wrote in their invited commentary (J Thorac Cardiovasc Surg. 2016;152:128-30). “In other words: BITA – just do it!” they wrote.

Because the survival advantage of BITA in CABG typically becomes apparent 10 years or more after the operation, the Johns Hopkins study, along with the Arterial Revascularization Trial that compares BITA with single ITA (Semin Thorac Cardiovasc Surg. 2014;26:76-94), can help redefine how cardiac surgeons select conduits for CABG, the commentators said.

“What does this particular study add?” they asked. “Point estimates for the adjusted hazard ratio of death or repeat revascularization were close to unity for each of the primary grafting hypothesis comparisons.”

Dr. Deb and Dr. Fremes had no financial relationships to disclose.




Cardiac surgeons have been slow to embrace bilateral internal thoracic arteries (ITAs) for coronary artery bypass grafting (CABG) despite accumulating evidence that this technique achieves better long-term survival than the single-artery technique, perhaps because they think the bilateral technique is more difficult. However, investigators from Johns Hopkins University have found no difference in results between four different bilateral ITAs techniques regardless of complexity.

Their single-center study analyzed outcomes from 762 patients at Johns Hopkins who had CABG by way of one of four different bilateral ITA (BITA) techniques between 1997 and 2014. The results are in the July issue of the Journal of Thoracic and Cardiovascular Surgery (2016;152:120-7).

“We found no significant difference in terms of long-term survival or freedom from repeat revascularization between different configurations of BITA use,” wrote J. Trent Magruder, MD, and his colleagues.

Dr. Magruder and his coauthors cited 13 reports that found BITA achieved better graft patency and long-term survival than did single internal thoracic arteries, but they noted the lack of reports comparing different BITA techniques. “Given the paucity of comparative data on long-term outcomes of various BITA configurations, we sought to study differences in mortality and the need for repeat revascularization among patients receiving varying BITA graft configurations at our institution,” they said.

The four groups and types of BITA procedures they analyzed were:

LL/RL group, in situ left ITA (LITA) anastomosed to the left anterior descending artery (LAD) with in situ right ITA (RITA) anastomosed to the left coronary circulation (n = 239).

LL/RR group, in situ LITA-LAD and in situ RITA-right coronary circulation (n = 239 patients).

RL/LL group, in situ RITA-LAD with in situ LITA-left coronary circulation (n = 185 patients).

Y group, in situ LITA-LAD with a free RITA as a composite graft with inflow from the LITA or a saphenous vein graft (n = 99 patients).

BITA cases comprised 5.7% of all 14,502 CABG procedures Johns Hopkins cardiac surgeons performed through the study period (60 BITA cases were dropped from the analysis because of incomplete data). That rate is about in line with a previously reported use rate of 4% of CABG procedures in the United States (Circulation. 2009;120:935-40).

Among the reasons Dr. Magruder and his coauthors cited for the lack of uptake of BITA among cardiac surgeons are discrepancies in survival data, a perceived high risk of complications such as sternal surgical site infections in patients with diabetes or chronic obstructive pulmonary disease or in those who are obese, and increased operative time and risk of bleeding.

With regard to the operation itself, the mean cross-clamp and coronary bypass times and number of bypass grafts were similar among all four groups, the latter ranging from 3.0 for the RL/LL group to 3.4 for the Y group. However, the researchers did find appreciable differences in rates of transfusions during the operation and skeletonization of the RITA at harvest. The Y group had the highest rates for both – 57.6% had transfusions and 72.7% had skeletonized RITA at harvest – followed by the RL/LL with rates of 43.2% for transfusions and 31.4% with skeletonized RITA. Rates for both intraoperative transfusion and RITA skeletonization were 24.7% and 8%, respectively, in the LL/RL group; and 37.7% and 18%, respectively, in the LL/RR group.

In-hospital complications, including reintervention for bleeding, heart attack, stroke, inflammation of the mediastinum, and death, were similar among all four groups. There were no in-hospital heart attacks. The only statistically significant difference was in hospital stay, ranging from an average of 6.1 days for the LL/RL group to 7.4 for both the LL/RR and RL/LL groups.

Through the duration of follow-up, the overall rate for repeat percutaneous coronary intervention was 7.6% – highest among the RL/LL (9.2%) and Y groups (9%). Those in the LL/RR group had the highest rates of repeat CABG: 1.7% vs. 0.8% for LL/RL group, 0.5% for the RL/LL group and 0% for group Y. Rates of late cardiac death were around 5% for the first three groups, but none were reported in group Y.

Dr. Magruder and colleagues acknowledged their study used a limited sample size for each procedure, but that their findings show that cardiac surgeons should choose their BITA configuration based on individual patient factors. “In general, the technically simplest operations should be selected because more complex procedures offer no additional benefit,” they said.

Dr. Magruder and his coauthors had no financial disclosures.

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