Predictors and Causes of Intraoperative Conversion From Off-Pump to On-Pump Coronary Artery Bypass: A Retrospective Study.

OBJECTIVE

This study evaluated the incidence, causes, and predictors of intraoperative conversion from off-pump coronary artery bypass grafting (OPCAB) to on-pump coronary artery bypass grafting (ONCAB), identifying risk factors to improve surgical planning.

METHODS

This retrospective case-control study included patients who underwent OPCAB at the Peshawar Institute of Cardiology, Peshawar, Pakistan, between December 8, 2021, and December 7, 2023. Among 714 patients, 27 (3.78%) required conversion to ONCAB. For comparison, 108 (15.1%) controls were randomly selected from those who completed OPCAB successfully. Preoperative and intraoperative data were analyzed, and logistic regression identified predictors of conversion.

RESULTS

The most frequent cause of conversion was hemodynamic instability, which occurred in 18 (66.67%) cases. Persistent hypotension and ST-segment changes lasting approximately 10-20 minutes were primary indicators before conversion, highlighting the need for close intraoperative monitoring. Left main coronary artery stenosis of 50%-70% emerged as the only independent predictor of conversion (odds ratio (OR) 7.60, 95% CI: 2.91-19.83, p < 0.001). This study emphasizes the importance of robust patient selection criteria, especially for cases with borderline coronary anatomy.

CONCLUSION

Hemodynamic instability and moderate left main coronary artery stenosis significantly contribute to OPCAB-to-ONCAB conversion. Enhanced preoperative imaging and hemodynamic management protocols can potentially reduce conversion rates, improving surgical outcomes.