Clinical Impact of High-Sensitivity Cardiac TnT Implementation
Quick Takes
- The transition from the 4th generation cardiac troponin T assay, to the 5th generation high-sensitivity cardiac troponin T assay, resulted in a marked increase in detection of myocardial injury and acute MI diagnoses, particularly in women and patients with type 2 MI.
- Despite the increase in MI diagnosis, implementation of the new assay was actually associated with reduced length of stay, stress testing, and resource utilization, other than angiography.
Study Questions:
What is the impact of transitioning from the 4th generation (Gen) cardiac troponin T (cTnT) assay to the 5th Gen high-sensitivity (hs) cTnT assay on the incidence of myocardial injury and myocardial infarction (MI) detection?
Methods:
This was a retrospective, observational cohort study of emergency department (ED) patients in two Southwest Wisconsin Mayo Clinic Health System hospitals. The study included measurements of cTnT during the transition from the 4th Gen (pre-implementation March 2018–September 2018) to 5th Gen hs-cTnT assay (post-implementation September 2018–March 2019). The 99th percentile upper-reference limit (URL) for the 4th Gen cTnT assay was <0.01 ng/ml, while it was sex-specific for the 5th Gen cTnT assay (10 ng/L for women and >15 ng/L for men). Primary diagnostic endpoints included the incidence of cTnT increases >99th percentile URL and diagnoses of myocardial injury and acute MI (both type 1 and 2), adjudicated following the Fourth Universal Definition of MI (UDMI). Primary resource utilization endpoints were length of stay, proportion of direct ED discharges, and cardiac testing (echocardiography, various stress testing modalities, coronary computed tomography, and invasive coronary angiography).
Results:
A total of 3,536 unique patients were evaluated, with 2,069 and 2,491 ED encounters pre-implementation and post-implementation, respectively. 284 patients had >1 ED presentation. Compared with the 4th Gen cTnT assay, encounters with ≥1 cTnT >99th percentile increased significantly when using the 5th Gen cTnT (15% vs. 47%; p < 0.0001; odds ratio [OR], 5.1; 95% confidence interval [CI], 4.4-5.9). Adjudication following the Fourth UDMI showed an increase of both acute MI (3.3% vs. 8.1%; p < 0.0001; OR, 2.60; 95% CI, 1.96-3.44) and myocardial injury (11% vs. 38%; p < 0.0001; OR, 4.85; 95% CI, 4.14-5.67). Furthermore, Type 1 MIs increased (1.7% vs. 2.9%; p = 0.0097; OR, 1.71; 95% CI, 1.13-2.57) but this increase was largely due to more type 2 MIs (1.6% vs. 5.2%; p < 0.00001; OR, 3.4; 95% CI, 2.31-4.99).
Women were less likely than men to have cTnT concentrations >99th percentile (9.7% vs. 20%; p < 0.0001), myocardial injury (7.5% vs. 16%; p < 0.0001), and acute MI (2.3% vs. 4.4%; p = 0.008) when using 4th Gen cTnT. There were no differences between men and women in the proportion of cases with cTnT concentrations >99th percentile, myocardial injury, and acute MI when using the 5th Gen cTnT. The impact on resource utilization included an overall reduction in length of stay and stress testing (p < 0.05), while coronary angiography was increased (p < 0.05). Among patients without cTnT increases, there was a significant increase in the proportion of patients directly discharged from the ED (60% vs. 74%; p < 0.0001), as well as reductions in echocardiography and stress testing (p < 0.05).
Conclusions:
The transition from 4th Gen cTnT to a 5th Gen hs-cTnT resulted in a marked increase in detection of myocardial injury and MI, especially in women and patients with type 2 MIs. Surprisingly, this increase in MI diagnosis did not result in an overall increase in resource utilization, and it markedly reduced length of stay, echocardiography, and stress testing in patients without cTnT increases.
Perspective:
In 2017, the Food and Drug Administration (FDA) approved the Roche 5th Gen hs-cTnT assay. This was followed by approval of several other hs-cTnI assays in 2018 and 2019. Limited data exist in the United States regarding the frequency of MI diagnoses and subsequent resource utilization with these newer assays. European data have suggested that the introduction of these assays was associated with improved MI rule-out processes, including reduction in the time to discharge, and a higher incidence of MI detection with only a modest increase in coronary angiographies performed. This study was the first US-based study to look at this impact, by comparing the contemporary cTnT assay with an overall 99th percentile to the hs-cTnT assay with sex-specific 99th percentiles. The findings were consistent with prior European data and also found that there was a marked increase in detection of myocardial injury and acute MI, specifically in women and patients with type 2 MI. Surprisingly, implementation of the new assay was actually associated with reduced length of stay, stress testing, and resource utilization. Future studies will need to assess whether implementation of this new hs-cTnT assay actually translates into improved outcomes for patients with suspected acute coronary syndromes and in particular focus on opportunities to improve cardiac care for women.
Clinical Topics: Acute Coronary Syndromes, Invasive Cardiovascular Angiography and Intervention, Noninvasive Imaging, Prevention, ACS and Cardiac Biomarkers, Interventions and ACS, Interventions and Imaging, Angiography, Computed Tomography, Echocardiography/Ultrasound, Nuclear Imaging
Keywords: Acute Coronary Syndrome, Biomarkers, Coronary Angiography, Diabetes Mellitus, Type 2, Diagnostic Imaging, Echocardiography, Emergency Service, Hospital, Exercise Test, Length of Stay, Myocardial Infarction, Patient Discharge, Primary Prevention, Tomography, X-Ray Computed, Troponin I, Troponin T, Women
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