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Algorithm improved rule-in, rule-out of MI within 1 hour
A strategy using an algorithm that incorporates high-sensitivity cardiac troponin-T values appears to be associated with ruling-out or ruling-in MI within 1 hour in 77% of patients with acute chest pain who presented to an ED.
The development of sensitive and high-sensitivity cardiac troponin tests appears to have improved the early diagnosis of acute MI, but how to best use these assays in clinical practice is not clear because the more sensitive tests have increased the number of positive results in conditions other than acute MI, according to study background information.
Researchers developed and validated an algorithm to rapidly rule-in or rule-out acute MI. The prospective, multicenter study enrolled 872 patients with acute chest pain presenting to the ED. Acute MI was the final diagnosis in 17% of patients.
The algorithm incorporated high-sensitivity cardiac troponin-T baseline values and absolute changes within the first hour.
The algorithm was developed in a sample of 436 patients and validated in the remaining 436 patients. Applying the algorithm to the validation cohort, 259 patients (60%) could be classified as rule-out, 17% could be classified as rule-in and 23% could be classified as being in the observational zone within 1 hour. Cumulative 30-day survival was 99.8%, 98.6% and 95.3% in patients classified as rule-out, observational zone and rule-in, respectively.
Results suggested that sensitivity and negative predictive value were 100% for rule-out. For rule-in, specificity was 97% and positive predictive value was 84%. In the observational group, prevalence of acute MI was 8%.
“The use of this algorithm seems to be safe, significantly shortens the time needed for rule-out and rule-in of acute MI and may obviate the need for prolonged monitoring and serial blood sampling in three of four patients with chest pain,” the researchers concluded.
In an accompanying editorial, L. Kristin Newby, MD, MHS, of Duke University Medical Center and a member of the Cardiology Today Editorial Board, wrote, “With increasing ED overcrowding, more effective tools are needed to enable rapid triage of patients with possible MI.
“With this study, Reichlin et al provide an important step forward in application of [high-sensitivity troponin] as a tool for triage of ED patients with possible MI. However, much work remains to develop the evidence to bring [high-sensitivity troponin] testing and the algorithms they have developed to use in clinical practice,” she wrote.
“Finally, although touted as ‘simple’ by the authors, the need for multicomponent algorithms that are different for rule-in and rule-out and that vary by age group or other parameters will challenge application by busy clinicians unlikely to remember or accurately process the proposed algorithm. As such, it will be imperative that [high-sensitivity troponin] algorithms, if validated, are built into clinical decision support layered onto electronic health records so that testing results are provided electronically to physicians along with the algorithmic interpretation to allow systematic application in triage and treatment,” Newby wrote.
For more information:
Newby LK. Arch Intern Med. 2012;doi:10.1001/archinternmed.2012.1808.
Reichlin T. Arch Intern Med. 2012;doi:10.1001/archinternmed.2012.3698.
Disclosure: The study was supported by research grants from the Swiss National Science Foundation, Swiss Heart Foundation, Abbott, Roche, Siemens and the Department of Internal Medicine at University Hospital Basel, Switzerland. The high-sensitivity cardiac troponin T assay was donated by Roche.