August 06, 2018
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Novel protocol with high-sensitivity troponin T accurately rules out MI

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A novel high-sensitivity troponin T protocol accurately ruled out MI in patients who visited an ED, according to a research letter published in Circulation.

“We anticipate that this procedure will allow many patients with chest pain to be given a ‘yes’ or ‘no’ diagnosis of whether they are having a heart attack faster,” Rebecca Vigen, MD, MSCS, cardiologist at UT Southwestern Medical Center in Dallas, said in a press release.

Researchers assessed the accuracy of the novel protocol in 536 patients (mean age, 55 years; 44% women) who presented with MI symptoms without ST elevations on ECG at an ED between August and October 2017.

The novel protocol, which included a 3-hour high-sensitivity troponin T measurement (Elecsys Troponin T Gen 5 STAT, Roche Diagnostics), was compared with a conventional fourth-generation high-sensitivity troponin T assay, which was tested at baseline and more than 3 hours after the patient presented with symptoms. Troponin T and high-sensitivity troponin T were measured at 0, 1 and 3 hours after presentation at the ED.

Patients were then categorized based on their high-sensitivity troponin T levels and changes. A patient was ruled out for MI if troponin T levels were less than 0.01 ng/mL for all measurements, whereas those considered to be abnormal had values greater than 0.01 ng/mL.

MI was diagnosed in 2.1% of patients, nonischemic myocardial injury was diagnosed in 17% and unstable angina was diagnosed in 0.4%.

The new high-sensitivity troponin T protocol ruled out MI in 83.8% of patients by 3 hours vs. 80.4% of patients using the conventional assay. With the new protocol, 30% of patients were ruled out at baseline, 24.8% at 1 hour and 28.9% at 3 hours.

The conventional assay determined that 19.6% of patients were abnormal vs. 16.2% using the new protocol (P = .03).

The sensitivity and negative predictive value of the new protocol was 100%, the positive predictive value was 13% and the specificity was 86%.

During 30 days of follow-up, no recurrent MI events occurred in the patients who were ruled out.

“Clinical judgment remains essential in the interpretation of abnormal troponin values as the [high-sensitivity troponin T] assay becomes adopted in the United States, where troponin is measured more indiscriminately than in many other countries,” Vigen and colleagues wrote. – by Darlene Dobkowski

Disclosures: Vigen reports no relevant financial disclosures. Please see the study for all other authors’ relevant financial disclosures.