Newsletter


Drug and Innovation Review

Off-Pump Coronary Artery Bypass Grafting: Is it Truly Better?

Mark A. Chaney, M.D.
University of Chicago

Off-pump coronary artery bypass (OPCAB) now constitutes approximately 25% of all isolated coronary artery bypass operations worldwide. Despite its increasing popularity, application of OPCAB varies greatly among individual surgeons. Some surgeons apply the technique to all patients, some surgeons apply the technique only to select patients, and some surgeons do not use the technique at all. Why such variance? There are many answers to this question. However, the two main reasons for variable adoption rates of OPCAB by individual surgeons are the lack of adequate well-designed (prospective, randomized, well-controlled) clinical studies and the unknown effects on long-term outcome (from decreased graft patency and/or inadequate revascularization).

The prime clinical advantage of OPCAB is avoidance of the detrimental physiologic effects of cardiopulmonary bypass (neurologic dysfunction, pulmonary dysfunction, renal dysfunction, hematologic abnormalities, etc.). However, it remains unclear whether or not OPCAB truly decreases morbidity, when compared to conventional coronary artery bypass operations with assist of cardiopulmonary bypass (1-3). The existing clinical investigations seem to indicate that OPCAB may favorably reduce blood transfusion requirements (from reduced perioperative blood loss), may favorably reduce the incidence of postoperative acute renal failure, may provide superior myocardial protection (from less myocardial necrosis), and may favorably reduce adverse neurological events, when compared to conventional coronary artery bypass operations with assist of cardiopulmonary bypass (4). However, the key word in the previous sentence is "may". The beneficial clinical effects of OPCAB (reduced morbidity) remain potential and unproven because of a lack of adequate well-designed studies. The vast majority of clinical investigations in this area are retrospective or observational in nature and originate from a single institution (with few surgeons). Obviously, definite conclusions regarding the beneficial clinical effects of OPCAB are difficult (if not impossible) to determine from such investigations. Interestingly enough, one of the few well-designed (prospective, randomized, blinded), fairly large (281 patients) clinical investigations comparing on-pump and off-pump coronary artery bypass graft surgery revealed no differences between the two groups regarding neurologic dysfunction (cognitive outcome and stroke rate), quality of life, and all-cause mortality at twelve months after operation(3).

Performance of OPCAB is not without risk. The unknown effects of OPCAB on long-term outcome (from decreased graft patency and/or inadequate revascularization) concern many surgeons. The technique is technically challenging and entails a substantial learning curve. It appears that early graft patency rates of the left internal thoracic artery-to-left anterior descending coronary artery anastomosis during OPCAB in selected patients in acceptable(4). However, extrapolating this finding to anastomoses in the lateral and inferior coronary artery distributions is premature at this time and long-term graft patency rates of all anastomoses are unknown(4). From the many clinical investigations published, it appears clear that patients undergoing OPCAB tend to receive a lesser number of bypass grafts (grafts may be abandoned because of technical challenges and/or hemodynamic instability). Such inadequate revascularization likely has a negative effect on long-term morbidity and mortality. Not surprisingly, a recent clinical investigation suggests that the operating surgeon's experience and expertise may play an important role in outcome following OPCAB (above and beyond beneficial effects of avoidance of cardiopulmonary bypass) (2,5).

In conclusion, the beneficial clinical effects of OPCAB remain controversial (4-6). Thus far, OPCAB has only been shown to be better than bypass grafting with cardiopulmonary bypass for noncritical endpoints in selected patients in the hands of selected surgeons (5). However, the technique is likely advantageous in certain circumstances (older patients, renal disease, etc.). Thus, proper application of the technique is of paramount importance. In each individual patient, potential benefits (avoidance of detrimental physiological effects of cardiopulmonary bypass) must be weighed against potential risks (decreased graft patency, inadequate revascularization) before deciding whether coronary artery bypass grafting should be performed with or without cardiopulmonary bypass.

References

1. Sabik JF, et al. Does off-pump coronary surgery reduce morbidity and mortality? J Thorac Cardiovasc Surg 124:698-707, 2002

2. Mack M, et al. Improved outcomes in coronary artery bypass grafting with beating-heart techniques. J Thorac Cardiovasc Surg 124:598-607, 2002

3. Van Dijk D, et al. Cognitive outcome after off-pump and on-pump coronary artery bypass graft surgery; A randomized trial. JAMA 287:1405-12, 2002

4. Mack MJ, Duhaylongsod FG. Through the open door! Where has the ride taken us? (Editorial). J Thorac Cardiovasc Surg 124:655-9, 2002

5. Bonchek LI. Off-pump coronary bypass: Is it for everyone? (Editorial). J Thorac Cardiovasc Surg 124:431-4, 2002

6. Mark DB, Newman MF. Protecting the brain in coronary artery bypass graft surgery (Editorial). JAMA 287:1448-50, 2002

Table of Contents:



© Society of Cardiovascular Anesthesiologists
Questions or comments? Please send email to webmaster@scahq.org