Introduction and Historical Context
By the 1990s and early 2000s, the technique gained traction with the advent of surgical stabilizers, CO₂ blowers, and intracoronary shunts. Yet, large-scale trials like the ROOBY study reported higher cardiac mortality and lower graft patency with OPCAB, largely due to the involvement of inexperienced surgeons and a homogenous (mostly male) veteran population. In contrast, studies conducted by seasoned surgeons, like the SMART and CORONARY trials, demonstrated comparable or better outcomes in terms of survival, graft patency, and reduced complications.
Current Status and Guidelines
While OPCAB is performed in less than 20% of CABG procedures in Western countries, its use exceeds 60% in countries like Korea and Japan. U.S. and European guidelines recommend OPCAB for specific cases such as patients with significant aortic calcification. They emphasize the importance of surgeon experience, noting that superior outcomes can be achieved when OPCAB is conducted in high-volume centers.
Clinical Outcomes and Meta-Analyses
Meta-analyses have confirmed that OPCAB outcomes closely match or sometimes exceed those of on-pump CABG, especially in high-risk patients. Notably, OPCAB is associated with a lower incidence of postoperative stroke, particularly when a no-touch aortic technique is used. The technique also shows advantages in reducing renal failure, bleeding, and ICU stays. However, concerns remain over graft patency—especially with vein grafts—though arterial conduits fare much better. The difference may stem from postoperative thrombocytosis and suboptimal antiplatelet therapy in earlier studies.
Applications in High-Risk Populations
The benefits of OPCAB become more pronounced in high-risk populations, such as octogenarians, patients with calcified aortas, and those with poor left ventricular function. In these cases, OPCAB reduces mortality, stroke, and atrial fibrillation rates. Registry data and trials like GOPCABE support its use in emergency situations, including PCI failures and cardiogenic shock, with conversion rates to on-pump surgery as low as 4.4%.
Challenges: Surgeon Training and Conversion Risks
Despite its advantages, OPCAB remains technically demanding. One of the major deterrents is the risk of emergent conversion to on-pump surgery, which can significantly worsen outcomes. Elective conversions pose less risk, but emergency situations demand swift decision-making and skill. Therefore, comprehensive training is essential. Animal labs using pig hearts and commercial simulators have emerged as effective tools for teaching the required dexterity for beating-heart anastomosis.
Future Directions: Total Arterial and Hybrid Strategies
The future of OPCAB lies in embracing its unique strengths. The an-aortic approach, which avoids aortic manipulation altogether, combined with total arterial revascularization using bilateral IMAs and radial arteries, can optimize long-term outcomes and minimize stroke risk. Unfortunately, adoption remains low in the U.S., where multiple arterial grafting is used in less than 15% of cases.
Hybrid coronary revascularization (HCR), which combines LIMA-to-LAD grafting with PCI for other arteries, offers a minimally invasive and patient-friendly alternative. While HCR may not outperform complete arterial revascularization, it provides a pragmatic solution for patients and surgeons less familiar with OPCAB.
Conclusion
OPCAB is poised for broader adoption, particularly as the global patient demographic trends toward higher-risk profiles. While technically challenging, its advantages—including reduced stroke risk, faster recovery, and improved outcomes in complex cases—make it a valuable surgical technique. Surgeons must invest in mastering both on-pump and off-pump CABG to tailor interventions to individual patient needs. If widely adopted with a focus on training and innovation, OPCAB could redefine the future of coronary revascularization.
