Mid-term results of the Radial Artery Patency and Clinical Outcomes randomized trial

How to build a multi-arterial coronary artery bypass programme: a stepwise approach

Observational evidence shows that the use of multiple arterial grafts (MAG) is associated with longer postoperative survival and improved clinical outcomes. The current European Society of Cardiology/European Association for Cardio-Thoracic Surgery Guidelines on myocardial revascularization recommend the use of MAG in appropriate patients. However, a significant volume-to-outcome relationship exists for MAG, and lack of sufficient experience is associated with increased operative risk. A stepwise approach to building experience with MAG allows successful implementation of this technique into routine coronary surgery practice.

The Use of Radial Artery for CABG: An Update

We used the radial artery as a second target conduit for coronary artery bypass grafting since 1971. However, randomized clinical studies have demonstrated differences in clinical outcomes between the radial artery and other grafts because these trials are underpowered. As we proceed toward 50 years of experience with radial artery grafting, we examined the literature to define the best second-best target vessel for coronary artery bypass grafting. The literature was reviewed with emphasis, and a large number of randomized controlled trials, propensity-matched observational series, and meta-analyses were identified with a large patient population who received arterial conduit and saphenous vein grafts. The radial artery has been shown to be effective and safe when used as a second target conduit for coronary artery bypass grafting. Results and patency rates were superior to those for saphenous vein grafting. It has also been shown that the radial artery is a safe and effective graft as a third conduit into the territory of the artery right coronary artery. However, there is little evidence based on a few comparable series limiting the use of the gastroepiploic artery. In its fifth decade of use, we can finally deduced that the aorto-to-coronary radial bypass graft is the conduit of choice for coronary operations after the left internal thoracic artery to the left anterior descending artery.

Second best conduit-is it the tag or patency that counts?

The Radial Artery Patency and Clinical Outcomes (RAPCO) trial compared radial artery (RA) with free right internal thoracic artery (RITA) and saphenous vein grafts (SVG). This was a prospective, randomized, single-center trial with two separate arms (RA-RITA and RA-SVG). The study showed that RA was superior to free RITA in terms of 10-year angiographic patency and provided a survival advantage as well. In contrast, RA-SVG comparison suggested a trend towards better outcomes with RA but no statistically significant difference in patency or survival. In this appraisal of the RAPCO trial, both the conduct and the findings have been critically evaluated. The concerns over using free RITA as aorto-coronary grafts as opposed to composite grafts and the insufficient sample size for the RA-SVG comparison have been highlighted. In the RAPCO trial that spanned almost quarter of a century, patency of all three conduits studied in the trial appears satisfactory.

Radial Artery Patency and Clinical Outcome Study (RAPCOS) Trial

Dr. O.P. Yadava, CEO and Chief Cardiac Surgeon, National Heart Institute, New Delhi, India, and Editor-in-Chief, Indian Journal of Thoracic and Cardiovascular Surgery, in conversation with Dr. Jai Raman from the University of Melbourne on the Radial Artery Patency and Clinical Outcome (RAPCO) Trial.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12055-020-01111-y.

Radial Artery Versus Right Internal Thoracic Artery Versus Saphenous Vein as the Second Conduit for Coronary Artery Bypass Surgery: A Network Meta-Analysis of Clinical Outcomes

Background

There remains uncertainty regarding the second‐best conduit after the internal thoracic artery in coronary artery bypass grafting. Few studies directly compared the clinical results of the radial artery (RA), right internal thoracic artery (RITA), and saphenous vein (SV). No network meta‐analysis has compared these 3 strategies.

Methods and Results

MEDLINE and EMBASE were searched for adjusted observational studies and randomized controlled trials comparing the RA, SV, and/or RITA as the second conduit for coronary artery bypass grafting. The primary end point was all‐cause long‐term mortality. Secondary end points were operative mortality, perioperative stroke, perioperative myocardial infarction, and deep sternal wound infection (DSWI). Pairwise and network meta‐analyses were performed. A total of 149 902 patients (4 randomized, 31 observational studies) were included (RA, 16 201, SV, 112 018, RITA, 21 683). At NMA, the use of SV was associated with higher long‐term mortality compared with the RA (incidence rate ratio, 1.23; 95% CI, 1.12–1.34) and RITA (incidence rate ratio, 1.26; 95% CI, 1.17–1.35). The risk of DSWI for SV was similar to RA but lower than RITA (odds ratio, 0.71; 95% CI, 0.55–0.91). There were no differences for any outcome between RITA and RA, although DSWI trended higher with RITA (odds ratio, 1.39; 95% CI, 0.92–2.1). The risk of DSWI in bilateral internal thoracic artery studies was higher when the skeletonization technique was not used.

Conclusions

The use of the RA or the RITA is associated with a similar and statistically significant long‐term clinical benefit compared with the SV. There are no differences in operative risk or complications between the 2 arterial conduits, but DSWI remains a concern with bilateral ITA when skeletonization is not used.

Vasodilatory Efficacy and Impact of Papaverine on Endothelium in Radial Artery Predilatation for CABG Surgery: in Search for Optimal Concentration

OBJECTIVE

The aim of this study was to compare the efficacy of two different papaverine concentrations (0.5 mg/ml and 2 mg/ml) for vasospasm prevention and their impact on endothelium integrity.

METHODS

We have studied distal segments of radial arteries obtained by no-touch technique from coronary artery bypass graft (CABG) patients (n=10). The vasodilatory effect of papaverine (concentrations of 0.5 mg/ml and 2 mg/ml) was assessed in vitro, in isometric tension studies using ex vivo myography (organ bath technique) and arterial rings precontracted with potassium chloride (KCl) and phenylephrine. The impact of papaverine on endothelial integrity was studied by measurement of the percentage of vessel's circumference revealing CD34 endothelial marker.

RESULTS

2 mg/ml papaverine concentration showed stronger vasodilatatory effect than 0.5 mg/ml, but it caused significantly higher endothelial damage. Response to KCl was 7.35±3.33 mN for vessels protected with papaverine 0.5 mg/ml and 2.66±1.96 mN when papaverine in concentration of 2 mg/ml was used. The histological examination revealed a significant difference in the presence of undamaged endothelium between vessels incubated in papaverine 0.5 mg/ml (72.86±9.3%) and 2 mg/ml (50.23±13.42%), P=0.002.

CONCLUSION

Papaverine 2 mg/ml caused the higher endothelial damage. Concentration of 0.5 mg/ml caused better preservation of the endothelial lining.

Lessons learned from Radial Artery Database International ALliance (RADIAL)

Coronary artery bypass graft (CABG) surgery was first performed in the 1960s. As the surgery has evolved, there has been a growing interest in the use of multiple arterial grafts in CABG. Since the re-introduction of the radial artery (RA) to clinical use as a bypass conduit in the 1990s, there have been several randomized controlled trials (RCTs) which have compared saphenous vein graft (SVG) conduits to RA use in CABG. While most trials have shown improved patency of the RA, none of them have been able to demonstrate a survival benefit using the arterial conduit. In this review, we examine the existing RCTs on the subject. We then look at our solution to the decades-old inquiry regarding the RA compared with the SVG. The Radial Artery Database International ALliance (RADIAL) project is an individual patient-level meta-analysis developed to adequately power a study to assess if the RA has superior clinical outcomes compared with the SVG. We describe the process by which this investigation was conducted and the collaboration necessary to achieve success.

Fifty years of coronary artery bypass grafting

Coronary artery bypass grafting (CABG) remains the most common cardiac surgery performed today worldwide. The history of this procedure can be traced back for more than 100 years, and its development has been touched by several pioneers in the field of cardiac surgery, who have contributed with both their successes and failures. With ever increasing follow up and number of patients treated, thinking regarding optimal CABG technique evolves continually. This article reviews the history of CABG from its early experimental work to recent technological advances.