Commentary: Long-term outcomes after internal thoracic artery grafting: Where does the time go?

Andrew M. Young, MD (left), Evan P. Rotar, MD, MS (middle), and Irving L. Kron, MD (right)

Who decides how we treat coronary artery disease? Do they have information to make the decision? Are they using it?

See Article page 106.

The continued evolution of cardiothoracic surgery and cardiology requires a constant reassessment of long-term outcomes. The debate over the most appropriate treatment for coronary artery disease continues; however, several populations have been identified as having the greatest benefit through randomized control trials, namely those with 3-vessel disease, diabetic multivessel disease, low ejection fraction, and left main disease.

Early data on outcomes by Yusuf and colleagues demonstrated improved mortality out to 12 years in patients who underwent coronary artery bypass grafting (CABG). Loop and colleagues and Cameron and colleagues demonstrated improved long-term patency when using the internal thoracic artery (ITA) compared with saphenous vein grafting. Atherosclerosis is rarely seen in the ITA conduit, and it is less susceptible to spasm due to manipulation, likely due to its reactivity to endogenous vasodilators. These excellent outcomes data have led to practice patterns shifting to favor ITA grafting whenever possible.

Ohno is to be commended for the thoughtful interpretation of the history and current state of CABG surgery and makes some interesting points about future directions. He describes a survival benefit to CABG with ITA over decades. He draws this conclusion based on the aforementioned studies on specific populations1, 2, 3, 4 as well as historical data looking at more general populations., He also suggests that age could be an important factor in determining appropriateness for CABG.

The first conclusion is reasonable, given the data. While the oldest studies may not reflect current medical therapy, patient demographics, or interventional techniques, follow-up from recent studies continue to support that ITA grafting has superior patency over 8 to 10 years.

The author frequently uses number needed to treat statistics (1/absolute risk reduction) to help illustrate the benefits of CABG on mortality and compare findings across studies. Figure 2 is nicely illustrative of the benefit demonstrated by Yusuf and colleagues on a population who only underwent saphenous vein grafting. However, we recommend caution when interpreting the Central Figure. The method for creating the outcomes curve is unclear and described as “conceptual” and appears to extrapolate on the first data point derived from a Lancet meta-analysis. Thus, while the concept behind the figure is appealing, it may be unintentionally misleading at first glance.

A major challenge in informing our colleagues and patients about long-term outcomes is that it will be difficult to ever obtain lifetime data on percutaneous coronary intervention versus ITA graft outcomes. In addition, the decision of whether to proceed with CABG or percutaneous coronary intervention is directed by the first person who sees the patient. We are curious to hear the author elaborate on how he would like age to factor into CABG decision-making and his supporting evidence. It will require long-term results from large data sets to determine the best procedure for young patients with coronary artery disease.