Clinically Acquired High Sensitivity Cardiac Troponin T is a Poor Predictor of Reduced Left Ventricular Ejection
Peter McLeod1, Sean Coffey1, Katherine Sneddon2
1Department of Medicine - HeartOtago, Otago Medical School, University of Otago, Dunedin, New Zealand; Department of Cardiology, Southern District Health Board, Dunedin, New Zealand.
Insights
Cardiac troponin levels (cTn) do not reliably predict left ventricular (LV) impairment after ST elevation myocardial infarction (STEMI). Routine troponin measurements are unsuitable for prioritizing patients for cardiac imaging due to poor predictive ability.
Area of Science:
- Cardiology
- Biomarkers
- Acute Coronary Syndromes
Background:
- Cardiac troponins (cTn) are historically used to estimate infarct size in ST elevation myocardial infarction (STEMI).
- In resource-limited settings, cTn could aid in prioritizing patients for cardiac imaging, such as echocardiography.
- The predictive utility of routinely collected cTn for significant left ventricular (LV) impairment requires evaluation.
Purpose of the Study:
- To determine the usefulness of routinely collected cardiac troponins (cTn) in predicting significant left ventricular (LV) impairment in ST elevation myocardial infarction (STEMI) patients.
- To assess the role of high-sensitivity troponin T (hsTnT) in stratifying LV dysfunction severity.
- To evaluate cTn's suitability for prioritizing patients for echocardiography in a resource-constrained environment.
Main Methods:
- Analysis of patients from the All New Zealand Acute Coronary Syndrome Quality Improvement (ANZACS-QI) registry with first STEMI (January 2013 - November 2018).
- Inclusion of patients with measured high-sensitivity troponin T (hsTnT); exclusion of those with no LVEF assessment, prior MI, or known LV dysfunction.
- Correlation of admission and peak hsTnT levels with left ventricular ejection fraction (LVEF) categories.
Main Results:
- 3,698 STEMI patients were analyzed.
- Higher mean hsTnT levels correlated with more severe LV impairment, but significant overlap existed between LVEF categories.
- Peak hsTnT showed poor discriminative ability for significant LV impairment (LVEF <40%), with an optimal cutpoint yielding 56.5% sensitivity and 65.3% specificity (AUC 0.62).
Conclusions:
- A weak association exists between peak troponin levels and the degree of LV dysfunction in STEMI patients.
- Significant overlap in troponin levels across different degrees of myocardial dysfunction limits its predictive value.
- Routinely acquired troponin is not suitable for clinical prioritization of patients for cardiac imaging.
Objective:
Cardiac troponins (cTn) have been used historically to estimate infarct size in ST elevation myocardial infarction (STEMI). Within a resource constrained health care environment, cTn could therefore be used for prioritisation of patients for cardiac imaging, in particular echocardiography. We aimed to determine how useful routinely collected cTn would be in predicting significant left ventricular (LV) impairment.
Methods:
All patients in the All New Zealand Acute Coronary Syndrome Quality Improvement (ANZACS-QI) registry with their first episode of STEMI between January 2013 and November 2018, who had high sensitivity troponin T measured, were included. We excluded patients with no left ventricular ejection fraction (LVEF) assessment, known LV dysfunction, or prior myocardial infarction.
Results:
In total, 3,698 patients were included in the analysis. A higher mean hsTnT (admission and peak) was seen in patients with more severely impaired LV function but there was significant overlap in the range of hsTnT between the different LVEF categories. Cardiac troponins demonstrated poor discriminative ability to either predict or exclude significant LV impairment (LVEF <40%). At an optimal cutpoint of 3,405 ng/L, peak hsTnT had a sensitivity of 56.5% (95% confidence interval [CI] 42-62%), a specificity of 65.3% (95% CI 62-79%) and an area under the receiver operating curve of 0.62 (95% CI 0.60-0.64).
Conclusion:
This is the largest study comparing clinically measured troponin levels and LV function in patients presenting with STEMI. A definite, but weak, association was seen between peak troponin and the degree of LV dysfunction, with significant overlap in troponin levels between levels of myocardial dysfunction. Routinely acquired troponin is not suitable for clinical use as a method of prioritising patients for cardiac imaging.
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