Cardiac troponin at 72 hours best predicts mortality after CABG
MedWire News: UK researchers say they have identified the cardiac troponin measurement that best predicts mid-term mortality after CABG surgery.
The team found that the cumulative area under the curve for cardiac troponin I (cTnI) at 72 hours (CAUC72) performed better than other postoperative troponometrics for prediction of mid-term mortality.
Inadequate myocardial protection during CABG could lead to myocardial injury, which in turn results in increased patient morbidity and mortality, write Domenico Pagano (University of Birmingham) and colleagues in the Annals of Thoracic Surgery.
The team set out to investigate associations between cardiac troponins, which are released in the majority of patients after CABG, and in-hospital and later mortality after CABG.
"The most discriminant measure of troponin would be useful to standardize clinical trials and consolidate longitudinal analyses of factors affecting outcomes, as well as directing targeted follow-up in patients identified to be most at risk," write the authors.
Pagano et al studied 440 patients undergoing isolated on-pump CABG with standardized anesthesia, perfusion, cardioplegia, and postoperative care between 2000 and 2004. They measured cTnI at baseline and at 6, 12, 24, 48, and 72 hours postoperatively. They also estimated timepoint cTnI at the same intervals, as well as peak cTnI increase between 6 and 12 hours, and 6 and 24 hours.
After a median follow-up of 7 years, 62 deaths occurred. Univariate analysis showed that standardized CAUC24, CAUC48, and CAUC72 were predictors of mid-term mortality, as were individual timepoint cTnI estimates at 12, 24, 48, and 72 hours, and the peak cTnI increase from 6-12 hours, and 6-24 hours.
When the authors performed multivariable analysis in models of logistic European System for Cardiac Operative Risk Evaluation (EuroSCORE) and creatinine clearance (CrCl), they found that both CAUC72 and the individual timepoint estimate at 72 hours were significant independent predictors of mortality (both p<0.001). Further research showed the best troponometric predictor of mortality based on the lowest Akaike information criterion (AIC) versus other troponometrics was also CAUC72.
"This confirms the importance of later release of cTnI as a surrogate marker of irreversible myocardial injury and suggests that future studies of myocardial protection should incorporate measurements up to and beyond this time point [72 hours] to best reflect myocardial damage after CABG," they commented.
Pagano et al conclude by stating that collection of cTnI data 72 hours postoperatively "would allow for more aggressive and earlier secondary prevention therapy as well as more vigilant follow-up."
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By Piriya Mahendra