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CABG with ITA for moderate stenosis improved long-term survival

Key clinical point: Grafting moderately stenosed coronary arteries using with internal thoracic arteries improved long-term survival.

Major finding: ITA grafting, compared with no grafting or use of a saphenous vein graft, yielded a 22% lower long-term mortality.

Data source: Researchers performed a prospective study of 8,531 patients from the Cleveland Clinic Cardiovascular Information Registry who had a single coronary artery with moderate stenosis.

Disclosures: The study was sponsored by the Cleveland Clinic and the Gus P. Karos Registry Fund. Dr. Sabik is the North American principal investigator for the Abbott Laboratories–sponsored left main coronary disease randomized trial and is on the scientific advisory board for Medtronic. The other authors had no disclosures.

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CABG: A still evolving art

Revascularizing a vessel with a moderate lesion should be considered only in the context of future disease progression, according to Dr. Leora B. Balsam and Dr. Abe DeAnda, Jr., who provided invited commentary on the article. However, “it seems reasonable to consider bypassing a vessel with a moderate coronary lesion when CABG or cardiac surgery is otherwise indicated.” However, they point out that the choice of conduit for a vessel with a moderate lesion is a separate question.

Dr. Sabik and his colleagues found that survival was the same for grafted and nongrafted patients; however, when stratified according to type of graft (ITA vs. saphenous vein), there was improved long-term survival with the ITA graft when compared with saphenous vein grafting and nongrafting. The researchers concluded that grafting coronary arteries with moderate stenosis is not harmful, that ITA grafting is associated with improved survival, and finally that bilateral ITA grafting should be performed even if the non-LAD target is only moderately stenosed. This final conclusion demands more consideration, according to Dr. Balsam and Dr. DeAnda, Jr. (J Thorac Cardiovasc Surg. 2016;151:812-4).

“Sabik and colleagues’ final assertion, that ‘after placing the first ITA to the left anterior descending, the second ITA should be placed to the second most important coronary artery, even if it is moderately stenosed,’ is provocative when taken in the context of prior published work in this area, including their own. At first glance, one might conclude that the survival benefit seen with ITA grafting was due to patients who received a single ITA to a moderately stenosed LAD,” Dr. Balsam and Dr. DeAnda, Jr. wrote.

“As we look to the future in coronary surgery, the art will continue to be challenged by new scientific discovery. Sabik and colleagues have provided yet another contribution to the science, and their work reminds us that we are still reaching for the tools to answer fundamental questions in coronary surgery,” they concluded.

Dr. Balsam and Dr. DeAnda, Jr. are from the department of cardiothoracic surgery, New York University.


 

FROM JOURNAL OF THORACIC AND CARDIOVASCULAR SURGERY

References

The overall use of coronary artery bypass grafting for angiographically moderate stenosis was found to be not harmful in a large, single-institution analysis of patients who were operated upon from 1972 to 2011.

In addition, the use of internal thoracic artery (ITA) grafting as compared with saphenous vein grafting or no grafting at all was positively associated with lower long-term mortality, according Dr. Joseph F. Sabik III and his colleagues at the Cleveland Clinic. Their study was published in the March issue of the Journal of Thoracic and Cardiovascular Surgery (2016;151:806-11).

Dr. Joseph F. Sabik

Dr. Joseph F. Sabik

The researchers assessed 8,531 patients from the Cleveland Clinic Cardiovascular Information Registry diagnosed with a single coronary artery that was moderately stenosed (50%-60%) that was bypassed in 6,598 cases (77%) and not bypassed in 1,933 (23%). Of those patients with bypasses, arteries were grafted with ITAs in 1,806 patients and saphenous veins (SVs) in 4,625 patients. The mean follow-up of all patients for all-cause mortality was 13 years.

Most ITA grafts went to the left anterior descending coronary artery (LAD) followed by diagonals and the left circumflex coronary artery (LC). Most SV grafts went to the right coronary artery, followed by the LCs and diagonals.

Dr. Sabik and his colleagues found that survival was similar for patients with or without a graft to the moderately stenosed artery: 97%, 76%, 43%, and 18% at 1, 10, 20, and 30 years for patients receiving no graft, versus 97%, 74%, 41%, and 18% among those receiving a saphenous vein graft, and 98%, 82%, 51%, and 23% among those receiving an ITA graft (P = .3).

However, when the researchers examined risk – adjusted based on patient characteristics, patients receiving an SV graft and no grafting had similar survival (P = .2), while the use of ITA grafting was found to be associated with a 22% lower long-term mortality (hazard ratio, 0.78; P less than .0001).

“ITA grafting of such [moderately stenosed] coronary arteries is associated with lower long-term mortality. Therefore, after placing the first ITA to the LAD, the second ITA should be placed to the second most important coronary artery, even if it is only moderately stenosed,” Dr. Sabik and his colleagues concluded.

The study was sponsored by the Cleveland Clinic and the Gus P. Karos Registry Fund. Dr. Sabik is the North American principal investigator for the Abbott Laboratories–sponsored left main coronary disease randomized trial and is on the scientific advisory board for Medtronic. The other authors had no disclosures.

mlesney@frontlinemedcom.com

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