Cardiac troponin I in the diagnosis of myocardial injury and infarction.

We used a cardiospecific enzymoimmunometric assay to measure cardiac troponin I (cTnI) in samples serially drawn from 78 patients with acute myocardial infarction (AMI), 7 patients with unstable angina (Braunwald class III), 22 multi-traumatized patients, and in 30 athletes after eccentric exercise, as well as in 101 non-traumatic chest pain patients on admission to the emergency department. cTnI assay crossreactivity with crude human skeletal muscle homogenates was < 0.1%. cTnI could not be detected in athletes or multi-traumatized patients except for 2 trauma patients with myocardial damage. Increased cTnI concentrations were found in 6 of 7 patients with unstable angina at rest and in all AMI patients. After AMI, cTnI increased about 3.5 h (median) after the onset of chest pain, reached peak values parallel to CKMB, and stayed increased for at least 4 days. Cardiac troponin T (cTnT) increased and mostly peaked parallel to cTnI. cTnT sensitivity on the 7th day after AMI was significantly higher than that of cTnI. In contrast to cTnI, cTnT mostly showed a second, usually smaller, peak about day 4 after AMI. During the first 4 h after the onset of chest pain and before thrombolytic therapy the sensitivities of myoglobin (0.43) and CKMB mass (0.56) were significantly higher than those of both troponins (cTnI, 0.29; cTnT, 0.25). Areas under receiver operator characteristic curves indicated only moderate diagnostic accuracies of bio-chemical markers for early AMI diagnosis in non-traumatic chest pain patients that cTnI is a highly sensitive and specific marker for myocardial damage which is suitable for early and late diagnosis.

Equivalent early sensitivities of myoglobin, creatine kinase MB mass, creatine kinase isoform ratios, and cardiac troponins I and T for acute myocardial infarction.

Early sensitivities of creatine kinase (CK), CKMB (activity and mass), CKMM and CKMB isoform ratios, myoglobin, cardiac troponin I (cTnI), and cardiac troponin T (cTnT) were compared to find the most sensitive serum marker for acute myocardial infarction (AMI) during the first hours after onset of chest pain. In a prospective study we investigated 37 consecutive patients with AMI who were admitted to the coronary care unit within 4 h after onset of chest pain. Blood samples were drawn every hour for the first 10 h after admission. CKMB mass concentrations, CKMM and CKMB isoform ratios, myoglobin, cTnI, and cTnT increased significantly (P < or = 0.0067) earlier than CK and CKMB activity and were also significantly (P < or = 0.046) and markedly more sensitive on admission. Differences in early sensitivities of myoglobin, CKMB mass, CK isoform ratios, cTnI, and cTnT were small and not significant. Therefore, turnaround time and practicality for emergency determination of methods, specificities of markers, the required specificity in the individual patient, and costs mainly determine the choice among myoglobin, CKMB mass, CK isoforms, cTnI, and cTnT.