Complex Coronary Artery Bypass Grafting: Intraoperative Challenges and Surgical Strategies in Contemporary Practice

Background: Contemporary coronary artery bypass grafting (CABG) is often performed in patients with diffuse atherosclerosis, severe calcification, prior percutaneous coronary intervention (PCI), and fragile myocardium, creating intraoperative scenarios that can compromise target selection, anastomotic quality, and completeness of revascularization. We synthesize operative strategies and outcomes across five predefined "complex CABG" scenarios. Methods: A focused literature review was performed targeting intraoperative CABG challenges in adult patients. Two reviewers independently screened titles/abstracts and selected studies describing operative details, technical considerations, or outcomes relevant to (1) intramyocardial/embedded coronaries, (2) severely calcified or diffuse disease requiring reconstruction, (3) small-caliber targets/flow-limited grafting, (4) iatrogenic right ventricular (RV) injury, and (5) failed PCI/stent-related surgical management. Disagreements were resolved through discussion and consensus. Results: Thirty core publications were synthesized across five complex intraoperative CABG scenarios (intramural/embedded coronaries n = 7; calcified/diffuse disease n = 7; small-caliber/flow-limited targets n = 7; iatrogenic RV injury n = 5; failed PCI/stent-related management n = 5). Intramural/embedded targets: reported intramyocardial LAD prevalence ranged from 2.2-13%, and studies emphasized structured localization strategies with a small but real risk of ventricular injury depending on technique. Severely calcified/diffuse disease: reconstructive approaches (endarterectomy, patch angioplasty, long-segment LAD reconstruction) were used to create graftable beds when standard anastomosis was not feasible, with series reporting acceptable early mortality and generally high early-to-midterm patency when paired with planned antithrombotic and imaging follow-up strategies. Small-caliber targets: vessel size alone did not preclude durable grafting when flow was optimized, with evidence supporting flow-augmenting designs (e.g., sequential grafting) and intraoperative flow verification to reduce low-flow failure in limited runoff beds. Iatrogenic RV injury: bailout techniques prioritized rapid hemostasis while preserving LAD/graft patency using buttressed closure concepts designed for constrained exposure and ongoing bleeding risk. Failed PCI/stent-related pathology: long stented segments shifted operative planning from distal target selection to target reconstruction (stentectomy/endarterectomy with long-segment LAD reconstruction), with angiographic follow-up cohorts demonstrating feasible revascularization but variable patency by territory and lesion extent. Conclusions: Complex CABG is best approached as structured, anatomy-driven problem-solving: deliberate target localization, creation of a graftable bed when needed, flow-augmenting graft design, and predefined bailout options. Standardized comparative studies are needed to define optimal strategies across these common clinically important scenarios.