title: Troponin T--a reliable marker of perioperative myocardial infarction?
abstract: Following cardiac surgery, electrocardiography and creatine kinase isoenzyme MB (CK-MB) activities are of limited value in diagnosing a non-transmural infarction. With the recent availability of an assay to detect serial levels of the specific cardiocyte contractile protein troponin T the possibility has been increased of closing a diagnostic gap among cardiosurgical patients. Ninety patients with severe diffuse three-vessel disease undergoing myocardial revascularization were grouped by their postoperative electrocardiographic (ECG) findings (group I--unchanged ECG; group II--new Q-waves representing perioperative myocardial infarction (PMI)). Serial levels of troponin T and the activity of CK-MB were measured 6, 12, 24 and 48 h after aortic unclamping. The course of CK-MB activity was compared to a profile and values derived from patients with unchanged (n = 1312) or new Q-wave ECGS (n = 89). In 72 patients (80.0%) with unchanged postoperative ECG (group I) serial troponin T levels remained constantly low and reached a median peak value of 0.37 microgram/l (quartile 0.13-0.50 microgram/l) after 24 h. Serial CK-MB activities demonstrated the typical non-ischemic course with a monoexponential decline from an initial median peak value of 15.5 U/l (quartile 12.0-21.0 U/l) to 7.0 U/l (quartile 6.0-9.0 U/l). In seven patients (7.8%) with new Q-waves and a pathologic CK-MB profile (group II) troponin T reached median levels of 10.47 micrograms/l (quartile 6.34-12.50 micrograms/l) (P < 0.001 I vs II). Four of five patients with a new right bundle branch block demonstrated low troponin T levels below 1 microgram/l and a normal CK-MB profile. Among six patients with unchanged QRS-configuration and elevated troponin T levels between 0.84 and 4.99 micrograms/l CK-MB activity showed a characteristic PMI pattern in two patients. Troponin T is characterized by a very narrow margin of normal values represented by a maximum third quartile of 0.50 microgram/l. A singular value of troponin after 6 h or 24 h may be sufficient evidence to confirm the diagnosis of a PMI.
authors.affiliation: Division of Cardiothoracic and Vascular Surgery, Johannes-Gutenberg University, Mainz, Germany.
authors.forename: U
authors.initials: U
authors.lastname: Hake
authors.forename: F X
authors.initials: FX
authors.lastname: Schmid
authors.forename: S
authors.initials: S
authors.lastname: Iversen
authors.forename: M
authors.initials: M
authors.lastname: Dahm
authors.forename: E
authors.initials: E
authors.lastname: Mayer
authors.forename: G
authors.initials: G
authors.lastname: Hafner
authors.forename: H
authors.initials: H
authors.lastname: Oelert
mesh_terms: D000368:Aged; D015415:Biomarkers / Q000097:blood; D003327:Coronary Disease / Q000601:surgery; D003402:Creatine Kinase / Q000097:blood*; D004562:Electrocardiography; D005260:Female; D006801:Humans; D007527:Isoenzymes; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000097:blood / Q000175:diagnosis* / Q000503:physiopathology; D011183:Postoperative Complications / Q000097:blood / Q000175:diagnosis* / Q000503:physiopathology; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity; D014336:Troponin / Q000097:blood*; D020107:Troponin T
chemical_list: D015415:Biomarkers; D007527:Isoenzymes; D014336:Troponin; D020107:Troponin T; D003402:Creatine Kinase