Aims Current troponin cut-offs suggested for the post-operative workup of patients following coronary artery bypass graft (CABG) surgery are based on studies using non-high-sensitive troponin assays or are arbitrarily chosen. We aimed to identify an optimal cut-off and timing for a proprietary high-sensitivity cardiac troponin I (hs-cTnI) assay to facilitate post-operative clinical decision-making. Methods and results We performed a retrospective analysis of all patients undergoing elective isolated CABG at our centre between January 2013 and May 2019. Of 4684 consecutive patients, 161 patients (3.48%) underwent invasive coronary angiography after surgery, of whom 86 patients (53.4%) underwent repeat revascularization. We found an optimal cut-off value for peak hs-cTnI of >13 000 ng/L [>500× the upper reference limit (URL)] to be significantly associated with repeat revascularization within 48 h after surgery, which was internally validated through random repeated sampling with 1000 iterations. The same cut-off also predicted 30-day major adverse cardiovascular events and all-cause mortality after a median follow-up of 3.1 years, which was validated in an external cohort. A decision tree analysis of serial hs-cTnI measurements showed no added benefit of hs-cTnI measurements in patients with electrocardiographic or echocardiographic abnormalities or haemodynamic instability. Likewise, early post-operative hs-cTnI elevations had a low yield for clinical decision-making and only later elevations (at 12–16 h post-operatively) using a threshold of 8000 ng/L (307× URL) were significantly associated with repeat revascularization with an area under the curve of 0.92 (95% confidence interval 0.88–0.95). Conclusion Our data suggest that for hs-cTnI, higher cut-offs than currently recommended should be used in the post-operative management of patients following CABG. Key question To describe the kinetics of high-sensitivity cardiac troponin I (hs-cTnI) after elective coronary artery bypass graft (CABG) surgery and assess which hs-cTnI cut-offs correlate with clinically meaningful findings. Key finding High-sensitivity cardiac troponin I levels determined 12–16 h after surgery with a cut-off of 8000 ng/L (307× upper reference limit) correlated best with a decision to repeat revascularization, while at earlier time-points, clinical decision should rather be based on electrocardiogram (ECG), echocardiographic, and haemodynamic criteria. Take-home message High-sensitivity cardiac troponin I aids decision-making when determined 12 h or later after CABG utilizing higher cut-offs than currently recommended, at earlier time-points workup should be based on ECG, echo, and haemodynamic criteria.
Background Great uncertainty exists about the indication for invasive coronary angiography (ICA) in patients with suspected acute coronary syndrome following cardiac surgery. Aim The aim of this study was to define clinical criteria that best identify patients who benefit from ICA after cardiac surgery. Methods We performed a retrospective analysis of all patients who underwent cardiac surgery between January 2009 and May 2019 at our center. Exclusion criteria included pediatric patients as well as pacemaker, TAVR and LVAD implantation and heart transplantation procedures. The primary outcome was usefulness of ICA as defined by consequent PCI or re-operation due to ICA findings. ECG changes (ST-elevations) and high-sensitivity Troponin I (hsTrop I) were analyzed. Results 48,136 patients were screened and after applying exclusion criteria 29,359 patients were finally included in the analysis (mean age 67.8±11.0 years, 31.1% females, Euroscore II 5.14±8.9%). A total of 1,171 patients (4%) underwent post-op ICA. The primary outcome occurred in 440 patients (1.5%) of which 290 underwent consequent PCI and 214 underwent consequent re-operation. Baseline characteristics are shown in table 1. Unadjusted analyses did not identify significant differences in the level of cardiac biomarkers between useful-ICA and unuseful-ICA groups. In multivariate regression analysis, only ST-elevation on ECG predicted the primary outcome (OR 1.33, 95% CI 1.003–1.76). Dichotomizing hsTrop I concentrations by applying the guideline-specified cut-off (>70x URL) resulted in correct classification of useful-ICA patients in 95.7%. However, the false-positive rate was also extremely high (83.6%) with a positive predictive value (PPV) of 1.6% and a negative predictive value (NPV) of 99.6% (accuracy 17.5%). Using area under the curve (ROC) analysis following optimal cut-off values for hsTrop I were identified: in CABG patients a cut-off value of >650x URL (corresponding absolute value 17000 ng/L) was defined with a corresponding sensitivity of 83.3%, specificity of 83.6%, PPV of 8.9% and NPV of 99.6% (accuracy 83.6%). In non-CABG patients (i.e. valve or aortic procedures), the cut-off was about twice as high as that for CABG patients (1,350x URL or 35,000 ng/L) with a corresponding sensitivity of 84.1%, specificity of 89.2%, PPV of 5.9% and NPV of 99.9% (accuracy 89.1%). Conclusion Our study demonstrates that currently recommended cut-off concentrations of high-sensitivity troponin are not useful for guiding clinical decision-making in patients with suspected acute coronary syndrome following cardiac surgery, while substantially higher cut-off values might be useful. Those cut-off values critically depend on the type of cardiac surgery performed (CABG vs. non-CABG). Troponin_Curves post-op Funding Acknowledgement Type of funding source: None
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