Using instantaneous wave-free ratio (iFR) to guide coronary bypass surgery dramatically improved graft survival rates compared to standard angiography alone. In this 78-patient randomized trial, iFR guidance achieved 80.5% graft patency versus 56.8% with conventional methods—a 23.7% absolute improvement in the critical left internal mammary artery-to-left anterior descending connection at 36 months. Saphenous vein grafts also showed superior survival (90.2% vs 70.3%). The iFR technology measures real-time blood flow pressure ratios to identify which blocked arteries truly need bypass grafts, preventing surgeons from grafting vessels where native circulation would compete with and potentially close the new bypass. This represents a significant advance in cardiac surgery precision, as graft failure remains a major cause of repeat procedures and adverse outcomes in the 400,000+ annual bypass surgeries worldwide. However, major cardiac events remained similar between groups, suggesting the patency benefits may not immediately translate to clinical protection. As an unreviewed preprint, these promising findings require peer validation and larger studies to confirm whether improved graft survival ultimately extends patient lifespan and reduces long-term cardiovascular risk.