The best 2nd conduit in coronary bypass graft surgery
Lead up statement: This study reports the 10 year outcomes of a patient-data level pooled analysis of randomized trials comparing the radial artery versus saphenous vein as –a CABG conduit.
Association of Radial Artery Graft vs Saphenous Vein Graft With Long-term Cardiovascular Outcomes Among Patients Undergoing Coronary Artery Bypass Grafting:
A Systematic Review and Meta-analysis
Mario Gaudino, MD; Umberto Benedetto, MD; Stephen Fremes, MD; Karla Ballman, PhD;
Giuseppe Biondi-Zoccai, MD; Art Sedrakyan, MD, PhD; Giuseppe Nasso, MD;
Jai Raman, MD, PhD;Brian Buxton, MD; Philip A. Hayward, MD; Neil Moat, MD; Peter Collins, MD; Carolyn Webb, PhD;
Miodrag Peric, MD; Ivana Petrovic, MD; Kyung J. Yoo, MD; Irbaz Hameed, MD; Antonino Di Franco, MD;
Marco Moscarelli, MD; Giuseppe Speziale, MD; John D. Puskas, MD; Leonard N. Girardi, MD; David L. Hare, MD;
David P. Taggart, MD; for the RADIAL Investigators[D2]
JAMA. 2020;324(2):179-187. doi:10.1001/jama.2020.8228
Impact of this article –
CABG is still the most commonly performed cardiac surgical procedure worldwide, with growing numbers in emerging economies and underdeveloped countries also. The left internal mammary artery, grafted to the left anterior descending coronary artery, is the cornerstone of this procedure with good long-standing durability. Grafts to the other vessels of the heart have conventionally utilized saphenous vein as aorto-coronary bypass grafts. In general, vein grafts are predisposed to develop atherosclerotic disease and tend to start blocking off beyond the first 5 years post-operatively.
Prof Brian Buxton was a pioneer 30 years ago in the evaluation, propagation and study of arterial grafts with hope of better long-term patency – the use of the radial artery and the right internal mammary artery were popularized by him, resulting in him having an international impact on surgical practice. This appeared transformational in achieving better long-term outcomes and survival in patients with coronary artery disease. Numbers of observational studies suggested the significant benefits for arterial grafts.
Of course, the only way to avoid the potential confounding issues of case selection of observational studies is to undertake randomized control trials (RCTs). One of the pioneering and most largest studies was undertaken at the Austin Hospital with patients randomized between 1995 and 2005: RAPCO (Radial Artery Patency & Clinical Outcomes) and then closely followed for the subsequent 10 years for both graft patency and clinical outcomes. A study of this kind has required a large team of investigators over a 25 year period. Prof Brian Buxton was always the energy behind the trial. He and Jai Raman, as well as being involved in the original protocol development, were the trial surgeons responsible for the largest numbers of patients enrolled and implanted with randomized grafts. Prof Prof David Hare has been a co-investigator from the start, ensuring scientific precision, rigorous follow up, event adjudication, data analysis and publications over the subsequent 25 years.
To get more power to analyse clinical outcomes, we linked the primary patient data from the 5 most rigorous RCTs that had compared the radial artery with saphenous vein grafts in a format that allowed differential analysis of the subsequent clinical outcomes. We called this the “RADIAL” collaboration.
The publication of our 5-year outcome data in the New England Journal of Medicine in 2018 demonstrated important clinical differences but without enough time elapsed for the differential rate of graft disease vein and arterial conduits to have had such a profound effect.
This recent publication in JAMA (Impact Factor 45.5) reports the 10-year clinical outcomes, demonstrating a marked advantage in favour of the radial artery grafts. Whilst not an a priori outcome, there was also a potentially significant all-cause mortality advantage (p<0.01). The accompanying editorial comment by Dr Steven Nissen of the Cleveland Clinic is also very enlightening. This paper should have a major impact on the international practice of coronary artery surgery.
As we evaluate the success of the Radial Artery, the 10 year results of our study RAPCO (Radial Artery Patency and Clinical Outcomes) is being published in Circulation (Impact Factor 23.6).
ORIGINAL RESEARCH ARTICLE Long-Term Results of the RAPCO Trials (Radial Artery Patency and Clinical Outcomes)
Brian F. Buxton, Philip A. Hayward, Jai Raman, Simon C. Moten, Alexander Rosalion, Ian Gordon, Siven Seevanayagam, George Matalanis, Umberto Benedetto, Mario Gaudino , MD, David L. Hare, On behalf of the RAPCO investigators
Circulation. 2020;142:00–00. DOI: 10.1161/CIRCULATIONAHA.119.045427
So, we go back to the premise - if one arterial graft (the LIMA to LAD) is good, two must be better and three the best....In any case, around the world, the standard seems to be LIMA to LAD and the rest of the coronary arteries being bypassed by saphenous vein grafts. Why? Vein is easy to harvest and can be done by one of the assistants while the main surgeon harvests the LIMA. We have shown over the past 20 years, that the Radial Artery can be harvested in a similar time without interfering with the flow of the operation. The most encouraging outcome is that we can effect better cardiovascular outcomes and improved survival with the use of the radial artery. The caveats are - that the radial artery has to be free of disease, and be able to be removed without compromising circulation of the forearm and hand. Also important, that the technique of harvest is atraumatic and safe so that the conduit can be used without the likelihood of spasm. This study was conceived by Prof Buxton and myself when I was finishing off my training in 1995. The long-term results are very supportive of our initial hunch - that the Radial Artery is significantly better than saphenous vein in staying open (patency) and outcomes. Amazingly, the radial artery was better than the free right internal mammary artery (part of that may be related to this smallish graft being attached to the aorta). This was the largest trial of the radial artery. We are now compiling our 15 year results.
Lets see how long this will take to catch on....