Troponin I as a diagnostic marker of a perioperative myocardial infarction in the orthopedic population.
OBJECTIVE
To assess the utility of troponin I, the only molecular marker of myocardial injury not expressed in regenerating muscle, in diagnosing perioperative myocardial infarction (MI) in the setting of orthopedic surgery where false elevations in creatine kinase MB isoenzymes (CKMB) are known to occur.


METHODS
Prospective study.


METHODS
University-affiliated hospital.


METHODS
85 patients with risk factors for coronary artery disease (CAD) who were scheduled for orthopedic surgery, including total knee arthroplasty, 34; total hip arthroplasty, 36; posterior spine fusion, 7; and other orthopedic operations, 8.


METHODS
Patients were observed in the postanesthesia care unit for at least 24 hours where they had an electrocardiogram (ECG) performed, and blood drawn to rule out MI.


METHODS
Blood samples for measurement of creatine kinase MB isoenzymes (CKMB) and troponin I were drawn at 8-hour intervals for up to 24 hours.


RESULTS
Five (5/85) patients had elevated levels of both CKMB and troponin I postoperatively. New ECG abnormalities were present in all but one patient who had an old anterolateral MI. Troponin I peaked within 16 hours except in one patient where it continued to increase. That female patient developed cardiogenic pulmonary edema. All the others did well clinically. Six patients (6/85) had a positive CKMB index, and a negative troponin I level. None had ECG changes, except for one in whom subsequent cardiac catheterization showed insignificant CAD. They all did well clinically. All patients with an elevated troponin I level had a positive CKMB index.


CONCLUSIONS
Troponin I is as sensitive a marker of MI as CKMB in the orthopedic population, but it has a higher specificity in the perioperative setting. Troponin I can be helpful in properly identifying the source of CKMB elevation postoperatively when this elevation is questionable.
Jules-Elysee
K
K
Department of Anesthesiology, Hospital For Special Surgery, New York, NY 10021, USA.
Urban
M K
MK
Urquhart
B
B
Milman
S
S
D000368:Aged; D015415:Biomarkers / Q000097:blood; D003402:Creatine Kinase / Q000097:blood; D052279:Creatine Kinase, MB Form; D004562:Electrocardiography; D005260:Female; D006801:Humans; D007527:Isoenzymes / Q000097:blood; D008297:Male; D009203:Myocardial Infarction / Q000175:diagnosis*; D019637:Orthopedic Procedures; D011183:Postoperative Complications / Q000175:diagnosis*; D011446:Prospective Studies; D012307:Risk Factors; D012680:Sensitivity and Specificity; D019210:Troponin I / Q000097:blood*
D015415:Biomarkers; D007527:Isoenzymes; D019210:Troponin I; D003402:Creatine Kinase; D052279:Creatine Kinase, MB Form