Prognostic significance of elevated cardiac troponin I after heart surgery.
BACKGROUND
Cardiac troponin I (cTnI) measured after heart surgery has been associated with operative mortality. We sought to determine whether measuring cTnI after heart surgery provides additional prognostic information beyond that provided by validated preoperative risk scores, the Veterans Affairs (VA) risk score and the European System for Cardiac Operative Risk Evaluation (EuroSCORE).


METHODS
We retrospectively collected cTnI levels measured 24 hours after surgery in 1,186 patients who underwent coronary artery bypass graft surgery (n = 696) or valve surgery (n = 490). The outcomes were operative death and perioperative myocardial infarction. The ability of the cTnI and the risk scores to discriminate patients who did or did not have the study outcomes was assessed by the area under the receiver operating curve (c-index).


RESULTS
Mean age was 66 +/- 10 years. Median cTnI was 38 ng/mL after valve surgery versus 18 ng/mL after coronary artery bypass graft surgery (p < 0.0001). There were 51 operative deaths (4.3%) and 142 perioperative myocardial infarctions (12%). For every 50 ng/mL increase in cTnI, the odds of operative death increased by 40% (odds ratio, 1.4; 95% confidence interval: 1.2 to 1.6) after coronary artery bypass graft surgery and by 30% (odds ratio, 1.3; 95% confidence interval: 1.1 to 1.5) after valve surgery. Cardiac troponin I was a significant independent correlate of perioperative myocardial infarction and death (p < 0.0001) with a c-index of 0.70 for death. Addition of cTnI improved the c-indexes of the risk scores for predicting death (from 0.75 to 0.79 for the VA risk score; p = 0.1; and from 0.69 to 0.77 for the EuroSCORE; p = 0.005).


CONCLUSIONS
Postoperative cTnI measured 24 hours after heart surgery is independently associated with operative death and perioperative myocardial infarction and improves the ability to predict operative mortality in comparison with preoperative risk scores alone.
Adabag
A Selcuk
AS
Division of Cardiology, Veterans Affairs Medical Center and the University of Minnesota, Minneapolis, Minnesota 55417, USA. adaba001@umn.edu
Rector
Thomas
T
Mithani
Salima
S
Harmala
John
J
Ward
Herbert B
HB
Kelly
Rosemary F
RF
Nguyen
John T
JT
McFalls
Edward O
EO
Bloomfield
Hanna E
HE
D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000097:blood; D006348:Cardiac Surgical Procedures / Q000009:adverse effects* / Q000401:mortality*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000097:blood* / Q000209:etiology; D011237:Predictive Value of Tests; D011379:Prognosis; D012189:Retrospective Studies; D012307:Risk Factors; D019210:Troponin I / Q000097:blood*
D015415:Biomarkers; D019210:Troponin I