Comparison of Troponin-T With Other Cardiac Markers in a VA Hospital

Measuring protein markers of cardiac damage is important for the diagnosis of myocardial infarction (MI). This study accessed the positive and negative predictive values of cardiac markers for detecting MI and perioperative MI in cardiac surgery by evaluating: creatine kinase (CK); creatine kinase MB isoenzyme mass assay (CK-MB); lactate dehydrogenase (LDH); lactate dehydrogenase isoenzyme-1 (LDH-1); myoglobin; and cardiac troponin T (cTnT) in a Veterans Affairs Medical Center. Inclusion criterion was any patient who had a CK ordered over a 6-month period. Patient history and diagnosis were obtained from discharge summaries. The two groups of patients studied either presented with symptoms of MI (n = 370), or underwent open heart surgery (n = 63). In the patients evaluated for MI, there were 433 suspected cardiac events with 48 MIs diagnosed. Cardiac marker sensitivities and specificities were cTnT (98% and 73%), CK-MB mass (81% and 97%), CK (73% and 78%), LDH (67% and 80%), LDH-1 (33% and 95%), and myoglobin (79% and 66%). For detecting MI, the marker that provided the optimum specificity was CK-MB mass, but cTnT had the highest negative predictive value. There was one perioperative MI in the 63 cardiac surgery patients. Surgical duration and aortic cross clamp time correlated with peak cTnT and CK-MB mass concentrations, but there was a wide degree of variability for any given time period.