Abstract
Serial high-sensitivity cardiac troponin (hsTn) testing in the emergency department (ED) and the intensive cardiac care unit may assist physicians in ruling out or ruling in acute myocardial infarction (MI). There are three major algorithms proposed for high-sensitivity cardiac troponin I (hsTnI) using serial measurements while incorporating absolute concentration changes for MI or death following ED presentation. We sought to determine the diagnostic estimates of these three algorithms and if one was superior in two different Canadian ED patient cohorts with serial hsTnI measurements. An undifferentiated ED population (Cohort-1) and an ED population with symptoms suggestive of acute coronary syndrome (ACS; Cohort-2) were clinically managed with non-hsTn testing with the hsTnI testing performed in real-time with physicians blinded to these results (i.e., hsTnI not reported). The three algorithms evaluated were the European Society of Cardiology (ESC), the High-STEACS pathway, and the COMPASS-MI algorithm. The diagnostic estimates were derived for each algorithm for the 30-day MI/death outcome for the rule-out and rule-in arm in each cohort and compared to proposed diagnostic benchmarks (i.e., sensitivity ≥ 99.0% and specificity ≥ 90.0%) with 95% confidence intervals (CI). In Cohort-1 (n = 2966 patients, 15.3% had outcome) and Cohort-2 (n = 935 patients, 15.6% had outcome), the algorithm that obtained the highest sensitivity (97.8%; 95% CI: 96.0–98.9 and 98.6%; 95% CI: 95.1–99.8, respectively) in both cohorts was COMPASS-MI. Only Cohort-2 with both the ESC and COMPASS-MI algorithms exceeded the specificity benchmark (97.0%; 95% CI: 95.5–98.0 and 96.7%; 95% CI: 95.2–97.8, respectively). Patient selection for serial hsTnI testing will affect specificity estimates, with no algorithm achieving a sensitivity ≥ 99% for 30-day MI or death.
Highlights
Guidelines support the use of early and serial testing with high-sensitivity cardiac troponin in patients with symptoms suggestive of acute coronary syndrome (ACS) for the diagnosis of acute myocardial infarction (MI) [1,2,3]
The benchmark for safety estimates for ruling out MI is attributed to an international survey response from emergency department (ED) physicians that reported an acceptable 30-day miss-rate of major adverse cardiac events
In both cohorts, there was no difference in the frequency of women assigned to the various groups with the three algorithms; differences in the other variables associated with risk were evident (Table 2)
Summary
Guidelines support the use of early and serial testing with high-sensitivity cardiac troponin (hsTn) in patients with symptoms suggestive of acute coronary syndrome (ACS) for the diagnosis of acute myocardial infarction (MI) [1,2,3]. We evaluated the three main published hsTnI algorithms that use serial measurements [3,5,14] in two different ED cohorts for 30-day MI or death (a common outcome reported by studies using these algorithms) [3,5,14]. In both cohorts, physicians were blinded to the hsTnI results with the cardiac troponin test being reported clinically belonging to a non-hsTn test version (note, standard, conventional or contemporary are terms that are used to describe non-hsTn tests). We examined whether patients identified in the rule-out arms would be classified as low-risk if the miss-rate for death or MI in these groups was ≤1% at 30 days
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