Is complete myocardial revascularisation with total arterial coronary artery bypass graft a dream or reality?

In 1986, Loop et al. first illustrated the long-term prognostic benefits of left internal mammary artery (LIMA) to left anterior descending graft.1 Surgical myocardial revascularisation with coronary artery bypass graft (CABG) surgery is the most commonly performed and preferred strategy for multivessel coronary artery disease.1, 2 In the absence of large enough powered randomized controlled trials (RCTs), recent studies observed that total arterial revascularisation (TAR) utilizing bilateral internal mammary artery (IMA) and radial conduits carry better longevity and reduces postoperative morbidity, particularly in early graft failure, recurrent angina, and redo-CABG surgery.3, 4 However, the potential challenge of TAR-CABG surgery, especially among left main coronary artery disease, depends on the premise that TAR will have a better graft patency rate and postoperative health-related quality of life.4-6 Here, we describe the long-term (≥6 months) survival benefits of myocardial revascularisation with multiple arterial CABG surgery over 20 years in the United Kingdom. A total of 2979 consecutive isolated elective CABG patients at St Georges University Hospital NHS Foundation Trust from April 1999 to March 2020 were studied, and the last day of the census was May 5, 2021. The study population was distributed in four groups—bilateral internal mammary artery + radial (BIMA+R; n = 431), single internal mammary artery + radial ± vein (SIMA+R±V; n = 823), single internal mammary artery − radial ± vein (SIMA−R±V; n = 823), and radial ± vein (R±V; n = 160) groups. The institutional review board clearance was waived as this retrospective analysis of prospectively collected data under the adult National Institute for Cardiovascular Outcomes Research UK database. Study inclusion criteria were isolated CABG with or without prior history of heart surgery, and patients with concomitant valvular, congenital heart diseases were excluded from the study. Multiple arterial graft CABG populations (BIMA+R and SIMA+R±V) have ≥3 arterial grafts, including sequential arterial grafts with the LIMA, right internal mammary artery (RIMA), and radial artery with or without venous grafts. A statistical package for the social sciences 25.0 version software was utilized to analyze the data, and a p value ≤ 0.05 is considered statistically significant. We found that males (~80%) are predominant, and the median age was 61 years (interquartile range [IQR]: 55–68), 63 years (IQR: 57–69), 72 years (IQR: 65–77), and 71 years (IQR: 65–77) in BIMA+R, SIMA+R±V, SIMA−R±V, and R±V groups, respectively. Gender distribution, male versus female, was 90.7% versus 9.3%; 81.2% versus 18.8%; 78.5% versus 21.5%; and 76.3% versus 23.7% among the BIMA+R, SIMA+R±V, SIMA−R±V, and R±V groups, respectively. Multiple arterial CABG (≥3 grafts) was performed in 45.5% and 39.9% cases among BIMA+R and SIMA+R±V populations, respectively. Further, 35.3% and 34.4% of patients had multiple (≥3) mixed arterio-venous grafting in SIMA−R±V and R±V CABG groups. We found that overall survival times were 19.1, 18.6, 15.8, and 10.9 years with BIMA+R, SIMA+R±V, SIMA−R±V, and R±V groups, respectively. Redo CABG was performed in four cases; two cases in each SIMA+R±V (0.2%) and SIMA−R±V (0.1%) group. A statistically significant (p ≤ 0.05) long-term (≥6 months) survival advantage for multiple arterial grafting was demonstrated, especially TAR, over all other combinations except single internal mammary artery + radial artery grafting (Figure 1). This study observed multiple arterial graft CABG population had better long-term survival, and the poorest outcome was in the R±V group with no IMA graft, similar to recently published articles where saphenous vein grafts are more prone to developing early graft failure and develop recurrent angina attacks, leading to poor quality of life and increased reintervention rate.6-8 We found the mean survival age was similar (19.1 vs. 18.6 years) among BIMA+R and SIMA+R±V groups might be due to the age at CABG surgery being identical and both belonging to multiple arterial graft CABG populations. In an RCT, Gaudino et al. observed that radial-artery grafts have a higher graft patency rate and a low adverse cardiac event over 5 years of follow-up, similar to our study results.9 The radial artery is believed to be disease-free with a good caliber and length, relatively resistant to the atherosclerosis process and has a good muscle layer facilitating better graft patency.7-9 In an international study coordinated in the United Kingdom, a randomized controlled trial pioneered by Taggart et al.10 evaluated the long-term mortality rate of bilateral versus single IMA grafts for CABG and observed no significant difference in all-cause of mortality over 10 years of follow-up, which is similar to other published articles.5-9 Moreover, Royse et al.,11 Rocha et al.,12 and Rayol et al.,13 observed better long-term survival benefits of multiple arterial CABG populations and encouraged the utilization of more arterial conduits, identical to the current study results. The preservation of graft patency is influenced by vascular endothelial nitric oxide (NO) and increased stress within the arterial circulation.14, 15 Nitric oxide helps maintain vascular tone, preventing platelet aggregation, white blood cell activation, thrombus formation, and smooth muscle cell proliferation. However, arterial conduits, particularly the radial artery, exhibit superior endothelium-dependent relaxation and remodeling under increased stress. In contrast, vein grafts show a decrease in the biological effects of NO and changes in gene expression, leading to vascular smooth muscle cell proliferation, acceleration of degenerative process, and atherosclerosis, which results in a poor graft patency rate.14, 15 According to the existing literature,8, 10, 13, 16 our revascularisation strategy was to achieve complete myocardial revascularisation utilizing more arterial conduits and arterial grafts (with sequential arterial grafts if needed) based on a distinct preoperative plan on angiographic findings to accomplish total arterial CABG. Further, existing articles6-8 found BIMA harvesting poses challenges for sternal wound infection; we found no significant long-term adverse outcome associated with utilizing BIMA grafts over 20 years. Insofar as we know, this is the most extensive TAR-CABG study in the United Kingdom; however, its nonrandomized retrospective observational methods put some methodological limitations despite enough statistical power. Although the study sample was male predominant and based on a heterogeneous group from a single institute, the survival rate in each study group and the odds ratio of potential risk factors are topics of high interest. Nevertheless, our redo-CABG cases were performed due to a new coronary lesion having study limitations as specific data on-site, territory, and percentage of the lesion is lacking. Furthermore, we believe an RCT or large observational study based on angiographic evaluation of graft patency rate following multi-arterial CABG will shed more light on this study outcome. Multiple arterial CABG surgery is feasible and has excellent long-term survival benefits compared to the mixed arterio-venous graft population over 20 years of follow-up. Aziz Momin: Conceptualization; formal analysis; methodology; resources; supervision; validation; visualization; writing—review and editing. Redoy Ranjan: Conceptualization; formal analysis; methodology; resources; validation; visualization; writing—original draft; writing—review and editing. Venkatachalam Chandrasekaran: Conceptualization; methodology; resources; supervision; validation; writing—review and editing. Redoy Ranjan is an Editorial Board member of Health Science Reports, and a coauthor of this article. To minimize bias, they were excluded from all editorial decision-making related to the acceptance of this article for publication. In accordance with the National Research Ethics Service, this retrospective study, using data already collated as patients received their usual care, did not require research ethics committee approval but adhered to international standards for GDPR (General Data Protection Regulation). The lead author Redoy Ranjan affirms that this manuscript is an honest, accurate, and transparent account of the study being reported; that no important aspects of the study have been omitted; and that any discrepancies from the study as planned (and, if relevant, registered) have been explained. The research data used to support the findings of this study are available from the corresponding author of this study upon request.

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