Prospective validation of a 1-hour algorithm to rule-out and rule-in acute myocardial infarction using a high-sensitivity cardiac troponin T assay

Abstract

Background: We aimed to prospectively validate a novel 1-hour algorithm using high-sensitivity cardiac troponin T measurement for early rule-out and rule-in of acute myocardial infarction (MI).

Methods: In a multicentre study, we enrolled 1320 patients presenting to the emergency department with suspected acute MI. The high-sensitivity cardiac troponin T 1-hour algorithm, incorporating baseline values as well as absolute changes within the first hour, was validated against the final diagnosis. The final diagnosis was then adjudicated by 2 independent cardiologists using all available information, including coronary angiography, echocardiography, follow-up data and serial measurements of high-sensitivity cardiac troponin T levels.

Results: Acute MI was the final diagnosis in 17.3% of patients. With application of the high-sensitivity cardiac troponin T 1-hour algorithm, 786 (59.5%) patients were classified as "rule-out," 216 (16.4%) were classified as "rule-in" and 318 (24.1%) were classified to the "observational zone." The sensitivity and the negative predictive value for acute MI in the rule-out zone were 99.6% (95% confidence interval [CI] 97.6%-99.9%) and 99.9% (95% CI 99.3%-100%), respectively. The specificity and the positive predictive value for acute MI in the rule-in zone were 95.7% (95% CI 94.3%-96.8%) and 78.2% (95% CI 72.1%-83.6%), respectively. The 1-hour algorithm provided higher negative and positive predictive values than the standard interpretation of highsensitivity cardiac troponin T using a single cut-off level (both p < 0.05). Cumulative 30-day mortality was 0.0%, 1.6% and 1.9% in patients classified in the rule-out, observational and rule-in groups, respectively (p = 0.001).

Interpretation: This rapid strategy incorporating high-sensitivity cardiac troponin T baseline values and absolute changes within the first hour substantially accelerated the management of suspected acute MI by allowing safe rule-out as well as accurate rule-in of acute MI in 3 out of 4 patients.

Trial registration: ClinicalTrials.gov, NCT00470587.

© 2015 Canadian Medical Association or its licensors.

Figures

Figure 1:

Performance of the high-sensitivity cardiac troponin T (cTnT) 1-hour algorithm for rapid diagnosis of acute myocardial infarction (MI).

Figure 2:

Kaplan–Meier curves showing cumulative mortality within 30 days (A) and 2 years (B) of follow-up according to the classification into “rule-out” (n = 786), “observational zone” (n = 318) and “rule-in” (n = 216) as determined by the high-sensitivity cardiac troponin T 1-hour algorithm.