Highly sensitive troponin assay shortens heart attack diagnosis

Aug 21 2012

By Piriya Mahendra, medwireNews Reporter

An algorithm that incorporates high-sensitivity cardiac troponin (hs-cTnT) could allow accurate rule-in and rule-out of patients with acute chest pain within 1 hour of presentation, a study shows.

"This novel strategy may obviate the need for prolonged monitoring and serial blood sampling in three of four patients," report Christian Mueller (University Hospital Basel, Switzerland) and team in the Archives of Internal Medicine.

They point out that although newly developed hs-cTnT assays have been shown to improve early acute myocardial infarction (AMI) diagnosis, the introduction of such assays into clinical practice has been difficult and confusing for physicians.

"Simple 'how-to-use' instructions for clinical decision making are critically needed to take clinical advantage of the new assays and to shorten the time to rule-in and rule-out AMI," they add.

Editorialist L Kristin Newby (Duke Clinical Research Institute, North Carolina, USA) also acknowledges the difficulty faced by clinicians in using a hs-cTnT algorithm and says that if validated, it must be built into clinician decision support layered onto electronic health records, so test results are provided electronically to physicians along with the algorithmic interpretation.

Therefore, the study by Mueller and team "is a major advance in understanding the application of hs-cTn testing that with continued development could substantially improve evaluation of [emergency department] (ED) patients with suspected MI," she remarks.

In Mueller and team's study, AMI was the final diagnosis in 17% of 872 patients with acute chest pain who presented to an ED. The hs-cTnT algorithm, which incorporated baseline hs-cTnT values as well as absolute changes within the first hour of presentation, was developed in a derivation cohort of 436 randomly selected patients and applied to the validation cohort of 436 patients.

A total of 259 (60%) patients were classified as rule-out, 76 (17%) patients as rule-in, and 101 (23%) as in the "observational zone," where patients neither fulfilled rule-out nor rule-in criteria, within 1 hour.

Overall, the authors say that using this algorithm, a safe rule-out as well as an accurate rule-in of AMI can be performed within 1 hour in three of four patients with chest pain, with a sensitivity and negative predictive value of 100%, a specificity of 97%, and a positive predictive value of 84%.

Moreover, 30-day mortality was 0.2% in patients ruled-out for AMI, "which underscores the suitability of these patients for early discharge," they add.

"Our findings extend and corroborate recent results regarding hs-cTnT assays and are of great clinical importance," comment Mueller et al.

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