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Electrocardiogram-Alterations and Increasing Cardiac Enzymes After Coronary Artery Bypass Grafting-When Can We Expect
Ali Taghizadeh-Waghefi1,2, Manuel Wilbring1,2, Asen Petrov1,2
1Medical Faculty "Carl Gustav Carus", Technical University of Dresden, 01307 Dresden, Germany.
Insights
Diagnosing perioperative myocardial infarction after coronary artery bypass grafting is challenging. Electrocardiogram (ECG) changes and cardiac biomarkers, particularly high-sensitivity troponin T (hsTnT) after 8 hours, can predict pathological findings in repeat angiography.
Area of Science:
- Cardiology
- Cardiac Surgery
- Diagnostic Imaging
Background:
- Perioperative myocardial infarction (PMI) after coronary artery bypass grafting (CABG) diagnosis is complicated by varied biomarker thresholds and ECG criteria.
- Accurate PMI detection is crucial for timely intervention and improved patient outcomes post-CABG.
Purpose of the Study:
- To assess the predictive capability of ECG alterations and cardiac biomarkers for identifying pathological findings on repeat coronary angiography in patients post-CABG.
- To determine the diagnostic utility of serial cardiac biomarker measurements (CK, CK-MB, hsTnT) and ECG changes at specific postoperative intervals.
Main Methods:
- Retrospective analysis of 137 patients undergoing repeat coronary angiography for suspected PMI after CABG.
- Evaluation of ECG changes and serial measurements of CK, CK-MB, and hsTnT at 4, 8, and 18 hours postoperatively.
- Correlation of diagnostic findings with graft-related complications or new coronary lesions identified during angiography.
Main Results:
- Pathological angiographic findings, primarily graft complications, were present in 85.4% of patients.
- ST-segment elevation and depression on ECG were significantly associated with pathological findings (p < 0.01 and p = 0.02, respectively).
- High-sensitivity troponin T (hsTnT) > 1231 ng/L at 18 hours demonstrated perfect diagnostic performance (AUC = 1.0, p < 0.01); earlier biomarker elevations lacked significant discriminatory value.
Conclusions:
- ECG is a rapid and accessible tool for initial PMI prediction.
- Cardiac biomarkers, especially hsTnT, gain diagnostic relevance beyond 8 hours postoperatively.
- A multimodal strategy combining ECG and biomarker kinetics, like ST-elevation with CK-MB > 1.0 µkat/L or hsTnT > 1231 ng/L at 18h, aids early decision-making in selected post-CABG patients.
Abstract:
Background and Objectives: Perioperative myocardial infarction (PMI) after coronary artery bypass grafting (CABG) remains difficult to diagnose due to varying biomarker thresholds and ECG criteria. This study aimed to evaluate the predictive value of ECG changes and cardiac biomarkers for identifying pathological findings in repeat coronary angiography after CABG. Materials and Methods: This retrospective study included 137 patients who underwent repeat coronary angiography due to suspected PMI. ECG changes and serial measurements of CK, CK-MB, and hsTnT were analyzed at 4, 8, and 18 h postoperatively. The primary endpoint was the identification of graft-related complications or new coronary lesions. Results: Pathological angiographic findings were detected in 85.4% (n = 117) of cases, predominantly graft-related complications (96.6%). ST-segment elevation (p < 0.01) and ST-segment depression (p = 0.02) were significantly associated with pathological findings. The combination of ST-segment elevation and CK-MB > 1.0 µkat/L also showed a high predictive accuracy (p < 0.01). HsTnT demonstrated the strongest diagnostic performance, with a threshold of 1231 ng/L at 18 h (AUC = 1.0; p < 0.01). Earlier postoperative biomarker elevations did not show significant discriminatory value. Conclusions: ECG remains the most accessible and fastest predictive tool for PMI detection. However, cardiac biomarkers only gain diagnostic relevance beyond 8 h postoperatively. A multimodal approach integrating biomarker kinetics and ECG changes may enhance early decision-making and improve patient outcomes, as ST-segment elevation in combination with CK-MB > 1.0 µkat/L serves as a relevant predictor. Notably, hsTnT levels > 1231 ng/L at 18 h reliably identified patients with pathological angiographic findings. These findings were derived from a highly selected cohort (~2% of all CABG patients) referred for coronary angiography and should therefore be interpreted as hypothesis-generating rather than directly generalizable to the broader surgical population.
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