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Published on: March 27, 2018
Which troponometric best predicts midterm outcome after coronary artery bypass graft surgery?
Aaron M Ranasinghe1, David W Quinn, Matthew Richardson
1School of Clinical and Experimental Medicine, University of Birmingham, Department of Cardiothoracic Surgery, University Hospital Birmingham, Birmingham, United Kingdom.
Insights
The cumulative area under the curve for troponin I up to 72 hours (CAUC72) best predicts midterm mortality after coronary artery bypass grafting (CABG). This measurement is crucial for assessing patient outcomes following cardiac surgery.
Area of Science:
- Cardiology
- Cardiac Surgery
- Biomarker Research
Background:
- Troponin I measurements are used to predict patient outcomes after coronary artery bypass grafting (CABG).
- The optimal troponin I measurement for predicting mortality after CABG has not been definitively established.
Purpose of the Study:
- To identify the most effective postoperative troponin I measurement for predicting in-hospital and late mortality after CABG.
- To compare various troponin I metrics in their ability to predict patient outcomes.
Main Methods:
- Cardiac troponin I (cTnI) levels were measured at baseline and 6, 12, 24, 48, and 72 hours postoperatively in 440 patients undergoing CABG.
- Individual time-point cTnI, peak cTnI, cTnI increase over time, and cumulative area under the curve (CAUC) were analyzed.
- Univariate and multivariable Cox models, incorporating logistic EuroSCORE and creatinine clearance, were used to assess mortality prediction.
Main Results:
- 62 of 440 patients died during a median follow-up of 7.0 years.
- Postoperative troponin I at 72 hours (T72) and CAUC72 were independent predictors of mortality.
- CAUC72 demonstrated superior predictive value based on the Akaike information criterion (AIC).
Conclusions:
- Serial troponin I data collection up to 72 hours postoperatively is recommended.
- The cumulative area under the curve for troponin I up to 72 hours (CAUC72) is the most effective troponometric marker for predicting midterm mortality after CABG.
- CAUC72 is valuable for myocardial protection studies and patient outcome assessment in cardiac surgery.
Background:
Various troponin I measurements (troponometrics) have been used as surrogate markers of patient outcome after coronary artery bypass grafting (CABG). Our aim was to define the postoperative troponometric best able to predict in-hospital and late mortality.
Methods:
In 440 patients (seen from January 2000 to September 2004) undergoing isolated on-pump CABG with standardized anesthesia, perfusion, cardioplegia, and postoperative care, we followed all-cause mortality (census June 2009, 100% complete). Subjects underwent troponin I (cardiac troponin I [cTnI]) estimation at baseline and 6, 12, 24, 48, and 72 hours postoperatively, and individual time-point cTnI (T6, T12, T24, T48, T72), peak cTnI (Cmax), increase in cTnI between 6 and 12 hours (T↑6-12) and 6 and 24 hours (T↑6-24), cumulative area under the curve cTnI (CAUC24, CAUC48, and CAUC72), and cTnI≥13 ng·mL(-1) at any time point were each analyzed using univariate and multivariable Cox models to identify the probability of in-hospital and late death. Logistic EuroSCOREs and calculated creatinine clearance (CrCl) were also included. The Akaike information criterion (AIC) was used to determine goodness of fit.
Results:
There were 62 of 440 deaths after a median (interquartile range) follow-up period of 7.0 (5.7 to 8.1) years. Univariate Cox analysis demonstrated T12, T24, T48, T72, T↑6-12, T↑6-24, standardized CAUC24, CAUC48, and CAUC72 each to be predictors of midterm mortality. On Cox multivariable analysis in models incorporating both logistic EuroSCOREs and CrCl, both T72 (hazard ratio [HR], 95% confidence interval [CI], 1.10 [1.06 to 1.14]; p<0.001) and CAUC72 (1.45 [1.26 to 1.62], p<0.001) were identified as independent predictors of mortality. Of these, CAUC72 was superior based on the lowest AIC.
Conclusions:
In myocardial protection studies, serial troponin I data should be collected until 72 hours postoperatively to calculate CAUC72, as this troponometric best predicts midterm mortality.
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