Long-Term Prognostic Value of Cardiac Troponin I and T Versus Creatine Kinase-MB Mass After Cardiac Surgery in Low-Risk Patients with Stable Symptoms

The long-term prognostic value of elevated cardiac biomarkers after elective cardiac surgery is not clear. The recent guidelines for diagnosing perioperative infarcts have advocated the use of similar thresholds for creatine kinase-MB (CK-MB) mass and the cardiac troponins. However, few previous data are available comparing these biomarkers after cardiac surgery, and it is not clear whether postoperative elevations of the troponins can be treated the same as elevations of CK-MB. We sought to compare the prognostic value of the cardiac troponins versus the CK-MB mass after elective cardiac surgery in low-risk patients with stable symptoms. A total of 204 consecutive patients undergoing cardiac surgery were included in the final analysis. Blood samples were drawn just before and 1 to 3 and 4 to 8 hours after the procedure, and every morning for 3 days thereafter. Patients with elevated baseline values were excluded. Using a cutoff value of 5 times the reference, patients with high and low values (controls) of CK-MB mass, cardiac troponin T (cTnT) and cardiac troponin I (cTnI) were compared. The median follow-up time was 92 months. None developed new Q-waves on the electrocardiogram. The incidence of the composite end point of all-cause mortality, readmission for acute coronary syndrome, and target vessel revascularization in the high CK-MB group was 41.2% compared to 21.8% in the controls (p = 0.004). The corresponding values for cTnT were 33.3% and 20.4% (p = 0.075) and for cTnI were 27.0% and 34.6% (p = 0.237). The p value in the isolated coronary artery bypass grafting subgroup (n = 156) was p = 0.043 for CK-MB, p = 0.137 for cTnT, and p = 0.795 for cTnI. High CK-MB (p = 0.001), ejection fraction (p = 0.002), and body mass index (p = 0.010) were the only variables independently related to reduced event-free survival. No such relation was found for high cTnT and cTnI. In conclusion, CK-MB was superior to the cardiac troponins (values ≥5 times the reference) in predicting long-term event-free survival after elective cardiac surgery in low-risk patients with stable symptoms undergoing coronary artery bypass grafting and/or valve surgery.