Long-term patency of bilateral internal thoracic artery Y composite coronary artery bypass grafts—determinants and impact on survival

BACKGROUND: Bilateral internal thoracic artery Y-composite grafting with sequential anastomoses is a well-established strategy for multi-arterial coronary artery bypass grafting. This study investigated the factors affecting long-term patency of bilateral internal thoracic artery Y-composite grafts and their influence on survival. METHODS: Patients who underwent coronary artery bypass grafting using bilateral internal thoracic artery Y-composite grafts due to triple-vessel disease were included. In total, 415 cases (2003–2020) with at least 1 postoperative coronary computed tomography or angiography examination were enrolled. Through a retrospective review of medical records and computed tomography, risk factors for graft events (string sign or occlusion) were analysed, and the influence of string sign or occlusion in the initial postoperative computed tomography on long-term survival was evaluated. RESULTS: Patients’ mean age was 66±9 years and 324 were male (78%). The mean number of anastomoses from bilateral internal thoracic artery grafts was 4.0±0.9. The mean follow-up duration was 8.0±4.0 years (interquartile range: 4.8–11.5 years). Beating-heart surgery negatively affected the patency of grafts to the left circumflex and right coronary artery territories (P=0.015 and P=0.030, respectively), but in the left anterior descending territory, the graft patency did not differ (P=0.053). Non-severe (<90%) native-vessel stenosis was a risk factor for poor patency in the left anterior descending, left circumflex, and right coronary artery territories (P<0.001 for all). Twenty-four of the 104 nonvisible or narrowed grafts (23%) on early imaging later became widely patent. Occlusion of the grafts or the string sign within postoperative 1 year did not have a negative impact on long-term survival (P=0.421). CONCLUSIONS: The patency rate was suboptimal in case of non-severe target-vessel stenosis (<90%). The beating-heart technique may negatively influence the patency of anastomoses to the left circumflex and right coronary artery territories. Compromised graft patency observed on initial computed tomography did not lead to worse survival.