A Prospective, Multicentre Randomised Controlled Study of Angiographic and Clinical Outcomes in Total Arterial Coronary Bypass Grafting: The TA Trial Protocol.

Background & Aim: Conventional coronary artery bypass grafting (CABG) procedures typically utilise the left internal mammary artery and supplementary saphenous vein grafts (SVGs) to re-establish adequate coronary blood flow to ischaemic territories. However, extensive observational studies have consistently demonstrated that SVGs are prone to accelerated atherosclerosis and progressive failure compared to arterial conduits. These limitations have heightened interest in total arterial revascularisation (TAR) as a potentially superior strategy.

Objective: The Total Arterial (TA) Trial, fully funded through the Medical Research Future Fund Cardiovascular Health Mission, aims to determine the angiographic and clinical outcomes of TAR compared to conventional non-TAR operations.

Method: Design: This study is an open-label, multicentre, randomised controlled trial including 1,000 CABG patients from multiple cardiac institutions across Australia, with an allocation ratio of 1:1. Randomisation occurs at a standardised perioperative time point via computer-generated sequences with variable block size The trial does not impose specific procedural requirements regarding the type of arterial conduit, revascularisation or reconstruction technique, use of sequential or composite methods, or any perioperative management.

Intervention: Total arterial CABG with no use of SVG.

Control: Non-total-arterial CABG with at least one SVG.

Main Outcomes: The primary endpoint will be perfect graft patency at 24 months postoperatively. The secondary endpoints include patency, major adverse cardiac and cerebrovascular events, quality of life, all-cause and cardiac mortality. Clinical follow-up visits will be scheduled at 6-month intervals, and angiographic assessments at 3 months and 24 months. Subgroup analyses by diabetes, sex, age, and conduit types are proposed to examine the potential interactions with treatment effects.

Conclusions: The TA Trial is one of the largest multicentre trials in the field of coronary revascularisation research, evaluating the graft status and clinical endpoints of TAR versus non-TAR procedures. The study design will provide valuable insights into whether differences in graft failure of SVG translate into differences in survival and cardiac outcomes. Early postoperative coronary angiography may improve understanding of the impact of competitive flow on graft function. The findings from this study will contribute to an improved understanding and help inform the optimal approach for coronary revascularisation, supporting evidence-based improvements in patient care.

Ethics: Ethical approval has been granted by the Melbourne Health Institutional Review Board (HREC/92839/MH-2023), Australia.

Trial Registration: The trial has been registered under the Australian New Zealand Clinical Trial Registry (registration number: ACTRN12623000864628). Dissemination of results: The analysed results will be published in a peer-reviewed journal on completion of the clinical trial.