Elsevier

American Heart Journal

Volume 164, Issue 5, November 2012, Pages 779-785
American Heart Journal

Clinical Investigation
Surgery
Troponin T is a better predictor than creatine kinase-MB of long-term mortality after coronary artery bypass graft surgery

https://doi.org/10.1016/j.ahj.2012.05.027Get rights and content

Background

Elevations of creatine kinase-MB (CK-MB) and cardiac troponin T (cTnT) have an uncertain long-term prognostic value after coronary artery bypass graft (CABG) surgery. We aimed to test the hypothesis that CK-MB and cTnT are predictors of long-term survival after CABG and to assess which of these 2 biomarkers is the better predictor.

Methods

A total of 1,350 consecutive patients undergoing isolated on-pump CABG had CK-MB and cTnT measured at 7, 20, and 44 hours, postoperatively. The end point was all-cause mortality, and during the median follow-up time of 6.1 years, 207 patients (15.3%) died.

Results

Both peak CK-MB and peak cTnT independently predicted long-term mortality (hazard ratio [HR] 1.003, 95% confidence interval [CI] 1.001-1.005, P = .007, and HR 1.31, 95% CI 1.17-1.46, P <.001, respectively) when analyzed in separate multivariate Cox models, adjusting for baseline demographic characteristics and perioperative risk factors. However, when analyzed simultaneously in the same Cox model, cTnT was a significant predictor (HR 1.31, 95% CI 1.13-1.51, P <.001), whereas CK-MB was not (P = .99). Similar results were found when the biomarkers were analyzed together in a Cox model adjusting for European System for Cardiac Operative Risk Evaluation. The differences in mortality between the biomarker groups were consistent also when analyzing strict quartiles of peak values of CK-MB and cTnT (P = .81 and P = .001, respectively).

Conclusions

Both CK-MB and cTnT are predictors of mortality after CABG surgery; however, our data suggest that cTnT is a better predictor of long-term mortality after CABG surgery than CK-MB.

Section snippets

Patients

One thousand three hundred fifty patients operated on consecutively for isolated CABG, in the time period from January 1, 2003, to December 31, 2006, at Oslo University Hospital, Ullevaal, were included in the study. Patients undergoing additional surgery to CABG were excluded. Data, registered prospectively, were obtained from the hospital database and from patient files. The study was approved by an institutional review board. Few data were missing, and these were coded as absent.

All-cause

Patient characteristics

A total of 1,342 patients were available for analysis, and of these, 1314 patients (97.9%) had complete cTnT and CK-MB values for all 3 postoperative time points, and 28 patients (2.1%) had values for 2 postoperative time points. The mean age ± SD for the cohort was 64.9 ± 10.0 years, and there were 1,089 men (81.1%). The all-cause mortality at 30 days was 0.67%. Totally, 207 patients (15.4%) died during a follow-up period of a median (interquartile range) of 6.1 (5.1-7.2) years. Patients who

Discussion

The present study evaluated the long-term prognostic significance of myocardial damage defined by CK-MB and cTnT release after CABG. We found that both CK-MB and cTnT were predictors of long-term all-cause mortality after CABG in our patient population. However, when analyzing the 2 cardiac markers in the same Cox model, cTnT was a highly significant predictor of mortality, whereas CK-MB was nonsignificant. Troponin T remained a highly significant independent predictor of mortality after

Conclusions

In conclusion, both CK-MB and cTnT are predictors of mortality after CABG surgery; however, our data suggest that cTnT is a better predictor of long-term mortality after CABG surgery than CK-MB. Further studies are warranted to identify the best follow-up regime for patients with postoperatively elevated cTnT.

Disclosures

None.

Acknowledgements

The authors are grateful for the help provided by Dr Stein Koldsland, Heidi Thorstensen, and the staff at the Department of Cardiothoracic Surgery, Oslo University Hospital, Ullevaal.

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