Determination of troponin I release after CABG surgery.
BACKGROUND
Troponin I is used to diagnose myocardial infarction (MI). Its use and pattern of elevation is not well defined in coronary artery bypass graft (CABG) surgery. This study assessed the timing of troponin I elevation in patients undergoing urgent CABG.


METHODS
Patients undergoing urgent isolated-CABG with cardiopulmonary bypass were studied prospectively. Blood samples were taken to measure CK, CK-MB, and troponin I: preoperatively, 7 hours postoperatively, 14 to 18 hours postoperatively, 30 to 48 hours postoperatively, and on postoperative day 4. Electrocardiograms and in-hospital course were recorded. Perioperative MI (PMI) was defined by either (i) ECG criteria of new Q-waves in the presence of CK-MB elevation >50 microg/L or (ii) CK-MB > 100 microg/L.


RESULTS
Of the 50 patients studied, 6 met the criteria for PMI (12%); 2 by criteria (i) and 4 by criteria (ii). In patients not meeting the criteria for MI the troponin I level peaked at 7 hour post-op with a mean of 20.97 microg/L (95% CI, 17.11 to 24.83). At this time, patients who met the criteria for MI had a mean troponin I level of 46.85 microg/L (95% CI, 36.40 to 57.30). Of variables investigated for the 44 patients who did not meet MI criteria, only preoperative troponin I level impacted peak postoperative troponin I.


CONCLUSIONS
CABG elevates troponin I far beyond current diagnostic benchmarks without the clinical occurrence of a MI and appears to peak during the second postoperative day. An elevated preoperative troponin I may predict an elevated peak postoperative troponin I in patients who do not have a PMI.
Noora
Joseph
J
McMaster University, Hamilton, Ontario, Canada.
Ricci
Christopher
C
Hastings
Deborah
D
Hill
Stephen
S
Cybulsky
Irene
I
D000368:Aged; D015415:Biomarkers / Q000097:blood; D001026:Coronary Artery Bypass / Q000009:adverse effects*; D003402:Creatine Kinase / Q000097:blood; D004562:Electrocardiography; D005260:Female; D006801:Humans; D007527:Isoenzymes / Q000097:blood; D008297:Male; D009203:Myocardial Infarction / Q000097:blood* / Q000201:enzymology / Q000209:etiology; D011184:Postoperative Period; D011379:Prognosis; D011446:Prospective Studies; D013997:Time Factors; D019210:Troponin I / Q000097:blood*
D015415:Biomarkers; D007527:Isoenzymes; D019210:Troponin I; D003402:Creatine Kinase