Graft selection remains a subject of debate in cardiac surgery. The use of the internal mammary artery (IMA) to revascularize the left anterior descending artery is the reference technique, as it has demonstrated both improved survival and lower complication rates. The application of a second IMA graft, which is recommended by clinical guidelines based on scientific evidence, remains contentious due to the results of recent studies. The only clinical trial on this topic, the ART study, contradicts recent works by Gaudino et al. and Magouliotis et al., likely due to methodological limitations of the former. Nevertheless, we generally accept that the evidence supporting the use of double IMA is robust. The use of a third arterial graft in cases of triple-vessel coronary artery disease represents an additional layer in this debate.

In this context, the meta-analysis by Formica et al. explores this third tier by comparing patients undergoing revascularization with BITA and RA versus BITA and SV. The authors conducted a comprehensive systematic review, focusing solely on articles using propensity score matching. Out of 523 publications, only six observational studies met the criteria, totaling 2500 patients (1250 in each group). Key data were analyzed: baseline patient characteristics, anastomosis configurations, coronary lesion severity, and statistical analysis quality. The primary endpoint was long-term mortality, with immediate postoperative mortality as a secondary outcome.

Results, with a follow-up time of 7.5–12 years, clearly favored complete arterial revascularization. Long-term survival was higher in the RA group (p = 0.031). Five-, ten-, and fifteen-year survival rates were also different between the groups, at 96.2%, 88.9%, and 83% in the RA group versus 94.8%, 87.4%, and 77.9% in the SV group. No differences were observed regarding immediate postoperative mortality.

The authors conclude that the use of RA as a third graft in addition to BITA is associated with improved long-term survival without increased immediate postoperative mortality.

COMMENTARY:

Multiple arterial revascularization in patients with coronary artery disease remains a hot topic in cardiac surgery. Despite numerous studies, clinical practice still reflects the preferences of individual surgeons, departments, or hospitals. This is evidenced by the estimated use of double IMA in only 12% of patients in Europe and 7% in the United States.

The RA has both detractors and advocates among cardiac surgeons, leading to heterogeneous usage. It was first used by Carpentier’s group in 1974 but was soon abandoned due to vasospasm issues, which were later mitigated by the development of the “pedicled harvesting technique” and the use of vasodilators, such as calcium antagonists. However, its use in severe arterial lesions, especially in the left coronary territory, has demonstrated excellent long-term patency, making it a strong option. The recent RAPCO study supports this theory, showing lower RA occlusion rates compared to SV.

The present meta-analysis by Formica et al. endorses RA use, reporting a significant long-term survival benefit with compelling results. However, certain aspects of this study warrant consideration:

• In terms of methodology, the inclusion of observational studies with propensity score matching introduces the inherent limitations of observational studies, along with the exclusion of studies that may have adjusted risk differently. Despite the high quality of the review and meta-analysis, conclusions are based on only six source articles, potentially excluding studies with confounding factor adjustments.
• Regarding the patient population analyzed, the mean age was under 70 years, notably younger than our usual practice in Spain. This lower mean age, which the authors acknowledge as a limitation, is also noted in editorials by Tatoulis and the Toronto group. It affects both baseline patient characteristics and comorbidities.
• One relevant piece of information is the RA graft location and vessel stenosis. It is known that using the RA in the right coronary artery territory with lesions <80% may not be beneficial, prompting a summary table of RA graft use in the included studies. Unfortunately, only four articles provided information, displaying a heterogeneous configuration challenging to analyze.
• A meta-regression study was performed to analyze the influence of risk factors on results, though age could not be analyzed due to data limitations, and no differences were found in other factors.

Even so, the study by Formica et al. is the first meta-analysis to evaluate the use of BITA and RA, concluding that there is no increase in immediate postoperative complications or mortality and that there is a clear long-term survival advantage. According to the raw number of patients in this study, there is an increase of 5 additional survivors per 100 surgeries at 15 years, effectively illustrating the significance of the “small percentage change” in Kaplan-Meier curves.

Therefore, we have further evidence in favor of complete arterial revascularization, adding to the RAPCO study results and prompting a reconsideration of our approach to the third tier of triple-vessel coronary artery disease treatment. It seems reasonable to conclude that the RA should be considered the best companion for double IMA, especially in younger patients.

REFERENCE:

Formica F, Maestri F, D’Alessandro S, Di Mauro M, Singh G, Gallingani A, et al. Survival effect of radial artery usage in addition to bilateral internal thoracic arterial grafting: a meta-analysis. J Thorac Cardiovasc Surg. 2023;165:2076-85.e9. doi: 10.1016/j.jtcvs.2021.06.062