Coronary artery bypass grafting remains one of the most effective treatments for multivessel coronary artery disease. The growing interest in multiple arterial grafting is supported by the superior long-term patency of arterial conduits and by the observed benefits in survival and freedom from repeat intervention. In this context, sequential RA grafting allows several coronary territories to be reached through a single conduit pathway, facilitating complete revascularization and potentially avoiding aortic manipulation. Despite technical advances, bypass graft success does not depend solely on conduit selection. Factors such as target-vessel quality, the severity of coronary stenosis, and anastomotic technique have been extensively investigated. However, the influence of the final graft geometry on clinical outcomes has received less attention. The possibility that certain angulations may induce haemodynamic disturbances capable of compromising distal graft patency represents an attractive and clinically relevant hypothesis.
The authors conducted a retrospective single-centre study including 197 patients who underwent surgery between 2010 and 2023. All patients received a LITA-LAD graft and a sequential composite graft constructed with the RITA and RA. Postoperative CCTA was used to measure the angle formed by the graft segments before and after the diagonal branch anastomosis. Patients were divided into a Narrow group (D-angle ≤90°; n = 16) and a Wide group (D-angle >90°; n = 181). The primary objective was to assess events related to the distal segment of the sequential graft, together with mortality and cardiac events during follow-up. Baseline characteristics were comparable between the groups.
After a median follow-up of 5.7 years, no significant differences were observed in overall survival or major cardiac events. However, patients with a narrow D-angle had a significantly higher incidence of events involving the distal sequential graft. Freedom from adverse sequential graft events at 1, 5, and 10 years was 74% in the Narrow group, compared with 93.6%, 92%, and 92%, respectively, in the Wide group (p = .008). In addition, a D-angle ≤90° remained an independent predictor of adverse events in the multivariable analysis (adjusted HR = 4.3; p = .014).
The authors concluded that an acute angulation represents a risk factor for distal graft failure and that its prevention should be considered during surgical planning and graft construction.
COMMENTARY:
The importance and particular interest of this article lie in its focus on an apparently minor technical detail that may nevertheless have major clinical consequences. In coronary surgery, we routinely consider conduit selection, the revascularization strategy, and the patient’s anatomical complexity. However, the final geometry of the bypass graft is rarely quantified objectively.
The study by Ohtani et al. does precisely this by transforming a surgeon’s subjective impression into a measurable anatomical variable with potential prognostic value. The pathophysiological explanation proposed by the authors is consistent with established principles of flow dynamics. An acute bend may create a low-flow region, thereby promoting intimal hyperplasia, early thrombosis, or RA vasospasm. It is particularly noteworthy that most graft-related events occurred during the first postoperative year, supporting the hypothesis of an early haemodynamic mechanism rather than progressive long-term graft deterioration.
Another relevant finding is that the study does not challenge the usefulness of sequential diagonal branch grafting itself. In fact, the stratified analyses suggest that the problem lies not in revascularizing the diagonal branch, but in certain unfavourable geometric configurations. This observation has important practical implications, as it allows the advantages of total arterial revascularization to be preserved without compromising procedural safety. When an excessive angulation is anticipated, alternative strategies such as individual grafts, other composite configurations, or hybrid revascularization could be considered.
From a surgical perspective, the study introduces a concept that can be readily incorporated into clinical practice. Careful evaluation of the graft course, both during preoperative planning and before chest closure, could help identify potentially problematic configurations. At a time when the use of arterial conduits and complete revascularization is increasingly encouraged, optimization of these technical details may have a meaningful cumulative effect on long-term outcomes.
Nevertheless, the findings should be interpreted cautiously. This was a retrospective, single-centre study with a relatively small sample, particularly in the Narrow group. The magnitude of the observed effect must therefore be considered with caution, and validation in larger cohorts is required. In addition, D-angle measurements were obtained from imaging studies performed under conditions that were not fully standardized. The influence of unrecorded anatomical or technical variables also cannot be excluded. Accordingly, these findings should be regarded as hypothesis-generating rather than definitive scientific evidence.
Despite these limitations, the study provides a novel perspective on an underexplored aspect of coronary revascularization surgery. Its principal merit is not only the identification of a potential factor associated with graft failure, but also the conversion of a traditionally subjective surgical impression into an objective and quantifiable anatomical variable. The introduction of the D-angle as a measurable parameter opens an especially attractive field of research and may contribute to optimizing the planning and performance of sequential arterial revascularization in the future.
REFERENCE:
Ohtani A, Yajima S, Yoshioka D, Kawamura A, Misumi Y, Kawamura T, et al. Impact of diagonal branch angle on cardiac outcomes after sequential coronary bypass surgery. Interdiscip CardioVasc Thorac Surg. 2026; 41 (4): ivag101. doi: 10.1093/icvts/ivag101
