TOC summary•The novel CCTA-derived LV%MYO method can objectively and individually quantify the amount of myocardium at risk of ischemia in SYNTAX segments downstream of a stenosed coronary artery, enabling the prospective prediction and retrospective assessment of complete revascularization.•In patients with complex coronary artery disease receiving coronary artery bypass grafting, there were significant differences between the fixed and theoretical myocardial blood flow as per the conventional …