Arterial Revascularization Trial (ART): What does it mean?

Podcast Transcript

Announcer: Welcome to Cleveland Clinic Cardiac Consult. Brought to you by the Sydell and Arnold Miller Family Heart & Vascular Institute at Cleveland Clinic. In each podcast, we aim to provide relevant and helpful information for healthcare professionals involved in cardiac, vascular, and thoracic specialties. Enjoy.

Dr. Faisal Bakaeen: Hello, my name is Faisal Bakaeen. I'm the Director of Surgical Coronary Vascularization at the Cleveland Clinic. We're gonna be commenting today about the finding of the ART study, the arterial revascularization trial. It was recently presented at the European Society of Cardiology. And the ten year results were presented. The ten year results came as a surprise. As were the five year interim results that were published in the New England Journal of Medicine last year showing no difference in outcomes between patients receiving single versus bilateral internal thoracic arteries four corner artery bypass grafting.

Dr. Bakaeen: The use of the internal thoracic artery in CABG was pioneered at the Cleveland Clinic. Dr. Loop and associates published a landmark study, in 1986, in the New England Journal of Medicine demonstrating the superior outcomes of patients receiving ITA grafts. Especially to the left anterior descending artery in terms of patency and also in terms of clinical outcomes. And ever since then, the ITA bypass to the LAD became a gold standard component of CABG.

Dr. Bakaeen: And it's a quality metric that's tracked by the STS, the Society of Thoracic Surgeons, and other quality entities. If the use of a single internal thoracic artery was of advantage then intuitively using two internal thoracic arteries might convey additional advantage in terms of graft patency and improved clinical outcomes. And in fact Dr. Lytle and associates published our findings from a large retrospective study showing just that.

Dr. Bakaeen: The only difference is the advance of using two internal thoracic arteries kicked in after five years. And the survival advantage in terms of separation of the curves continued with time. Meaning that the longer the follow-up, the more impressive or the more significant is the advantage of using the second internal thoracic artery.

Dr. Bakaeen: So we go back to our trial. Nobody really expected to see a real difference in outcomes at five years because that's too early. When the results of the ten years of ART were announced, the expectation at the clinic and at other centers that use bilateral internal thoracic arteries was that there will be a demonstration of survival advantage and a clinical advantage in terms of using bilateral internal thoracic arteries compared to a single internal thoracic artery. But in fact the study results were negative.

Dr. Bakaeen: But before we rush to conclusions, and stop using internal thoracic arteries, we have to try explain why the ART study was negative at ten years. First of all 36% of the patients in the ART study received a different treatment strategy than simply a single internal thoracic artery versus a double internal thoracic artery. 14% of patients that were supposed to receive bilateral internal thoracic artery bypasses, in fact only received one internal thoracic artery bypass. And 22% of patients who received a single internal thoracic artery and therefore were analyzed with the internal thoracic artery group as a single arterial conduit, in fact received another arterial conduit which is the radial artery.

Dr. Bakaeen: And we know now that the radial artery offers an advantage in terms of patency and clinical outcomes compared to veins. So inclusion of those 22% radial artery graft patients with the single internal artery narrowed the benefit margin of the group receiving the two internal thoracic arteries versus the group receiving a single internal thoracic artery.

Dr. Bakaeen: Another important factor is surgeon experience. Now one the reasons why there were crossover 14% as we mentioned between the bilateral internal thoracic arm and the single internal thoracic arm is probably related to surgeon inexperience. You could tell that by looking at the variation in the crossover between surgeons and centers. The more experienced surgeons and centers had less crossover. Surgeons that have completed 50 cases before the kickoff of the trial. And you look at the outcomes of those surgeons compared to the outcomes of those surgeons who did less cases and therefore were probably less experienced, you will see that there's a survival advantage for the bilateral internal thoracic arteries in the hands of the more experienced surgeon.

Dr. Bakaeen: Important take home message is this. Take the findings of our study with a pinch of salt meaning that the negative findings in the intention to treat analysis does not necessarily negate the advantages that could be conferred by multi-artery grafting for reasons that I've mentioned before. Using radial grafts can contribute improved outcomes and surgeon experience is a very important factor that needs to be imputed into the equation. Therefore, if your patient comes to your office and that patient is in need of coronary bypass grafting, I would urge the surgeon to evaluate the patients' physiologist and anatomic risk. And make the best possible decisions in terms of the revascularization strategy.

Dr. Bakaeen: If that patient is healthy and young, then strongly consider using multi-artery grafting strategies. If it's an older patient that is extremely high risk then obviously, the priority is the short term outcomes and getting that patient alive out of the operating room. And those patients in between those two extremes that I mentioned need to be evaluated on a case by case basis. But I think the default strategy should always be multi-arterial grafting until proven otherwise. Thank you very much.

Announcer: Thank you for listening. We hope you enjoyed the podcast. We welcome your comments and feedback. Please contact us at heart@ccf.org. Like what you heard? Please subscribe and share the like on iTunes.