Indicators of Graft Related Failure after CABG: A Detailed Analysis of 168 Re-angiographies

Background: Growing evidence in the literature indicates that early management of postoperative myocardial ischemia (PMI) through repeat coronary angiogram can attenuate the deleterious effect of ischemia. However absence of early indicators of graft related PMI can result in a high number of angiogram with normal findings. The present report sought to find out the indicators of early graft failure.

Methods: Between January 2006 and October 2013, 168 (4.2%) of 4028 patients who underwent isolated CABG had postoperative repeated coronary angiogram because of clinical diagnosis of PMI. To ascertain indicators of either graft-related or native vessel occlusion a logistic regression analysis was performed.

Results: Repeat coronary angiogram detected graft failure in 88 patients (52.4%), whereas new occlusions of native vessels were observed in 41 patients (24.4%). 39 patients (23.2%) had normal postoperative angiogram. Revision of CABG or PCI was performed in 30 (17.9%) and 60 (35.7%) patients respectively. Creatine Kinase-MB (CK MB) samples taken 12 and 24 hours after CABG were significantly more predictive for graft failure and native vessel occlusion than Troponin I values (ROC p = 0.007 and p = 0.009). Multivariate logistic regression analysis indicated a postoperatively progressive CK-MB elevation (p = 0.0450, OR 1.001) and CK MB threshold > 90U/L 12 hours after the CABG (p < 0.0073 OR 5.441) as independent predictors abnormal angiogram. ECG and major ventricular arrhythmia alone were not predictors of abnormal angiogram.

Conclusion: Postoperative CKMB is a better predictor of graft related myocardial infarct than troponins. Postoperative elevation of CKMB is a sign of persisting ischemia. Those predictors must be particularly considered for indication to postoperative angiogram.