Kinetics of Troponin I AND CK-MB after CABG as a Predictive Value for MACCE

Objectives: The impact of troponin I and CK-MB release as indicators for relevant perioperative cardiac ischemia and adverse clinical outcomes is not well defined. Reasons might be irregular laboratory analyses, varying center algorithms and the influence of renal function to plasma clearance. We investigated the kinetics of troponin I and CK-MB plasma concentrations in relation to renal function in elective CABG patients and its correlation to adverse clinical outcomes.

Methods: Between 2012 and 2017, a total 410 patients were treated by isolated CABG using cardioplegic arrest. For risk stratification STS score, EuroSCORE 2 (ES), KCH Score and SYNTAX Scores were calculated. Laboratory values of troponin I and CK-MB were determined preoperatively and 0, 4, 8, 24, 48, 72, 96, and 120 hours postoperatively. The glomerular filtration rate (GFR) was estimated using MDRD-formula. SYNTAX Score I and STS Score were correlated to MACCE especially to postoperative myocardial infarction (MI) via ROC curves.

Result: STS score was 0.9%, SYNTAX score was 23.3 ± 9.3. ES 2 had a median of 1.7%, KCH Score was 1%. MACCE occurred in 5.1% of patients with MI in 8 patients (2%) and stroke in 7 patients (1.7%). Hospital mortality was 0.5%.

Troponin I peaked after 48 hours (median of 1.1 ng/mL). The activity of CK-MB increased 8 hours postoperatively to 33.1 ± 29.9 U/L and thereafter decreased significantly. The calculated GFR (baseline 76.6 ± 23.1 mL/min/1.73 m²) showed no significant decrease postoperatively. Analyses of GFR subgroups revealed that troponin and CB-MK concentrations for subgroups of GFR > 90 and 60 to 89 mL/min/1.73 m² peaked after 48 hours (troponin) and 8 hours (CK-MB), respectively, while plasma clearance was significantly prolonged in GFR subgroups of 30 to 59, 15 to 29, and <15 mL/min/1.73 m². The correlation between troponin I and CK-MB was significant until 72 hours postoperatively, correlation coefficient was mean 0.45 (p < 0.01).The ROC curve of troponin I correlated best to MACCE after 120 hours (AUC: 0.74). The discrimination of CK-MB/MACCE was highest after 48 hours (AUC: 0.77). ROC curve of SYNTAX I Score/postoperative myocardial infarction was significant (AUC: 0.68).

Conclusion: Troponin in CK-MB plasma clearance is prolonged in reduced GFR. Troponin I and CK-MB showed a significant correlation during the early postop period. After 48 hours CK-MB and MACCE has the highest discrimination and coincides with the maximum of CK-MB. The additional determination of both biomarkers is a useful complement to the use of preoperative risk scores after CABG.

Publication History

Article published online:
19 February 2021