Dr. Amal Mattu on how a high-profile article on the HS-TN has prompted a flurry of uncertainty.
A physician recently emailed me with a question (paraphrasing): “Our lab recently switched over to using the new highly sensitive troponins’ and we’re confused. What do we do with a positive troponin?”
A handful of years ago, I suppose my gut response to someone asking what to do with a positive troponin (TN) test would have been to tell that person to do more CME before seeing any more patients. My feeling now, however, has become one of complete empathy with this physician and his colleagues. It seems we all are having a tough time figuring this out, including our own cardiologists. The most recent high-profile article pertaining to the highly sensitive troponin (HS-TN) test has prompted another flurry of emails, questions, and uncertainty. Here’s a quick summary of the article, then some further thoughts about the article, troponin testing, and evaluating patients with possible acute coronary syndromes.
Body R, Carley S, McDowell G, et al. Rapid exclusion of acute myocardial infarction in patients with undetectable troponin using a high-sensitivity assay. J Am Coll Cardiol 2011;58:1332-1339.
The authors of this study evaluated 703 patients presenting with chest pain to a large hospital’s emergency department (ED) in the United Kingdom. A total of 130 (18.5%) patients were diagnosed with acute myocardial infarction (AMI) using standard, accepted criteria for diagnosis using TNs, which incorporates a serial rise (or fall) of TN. Serial testing in this case meant that the researchers obtained a TN level (a high-sensitivity TN-T assay was used in this study) at the time of presentation and a second HS-TN at 12 hours after the onset of symptoms. Nearly half (46%) of patients presented within three hours of symptom onset, so the study did incorporate many early-presenters.
The authors found that of 130 patients diagnosed with AMI, 100% had an elevated HS-TN level at the time of presentation (95% confidence interval was 95.1% to 100%). In other words, NO patients with an initially negative HS-TN went on to have a positive HS-TN on serial testing. The authors suggest that this HS-TN would obviate the need for serial TN testing and therefore allow early discharge of these patients from the ED. Sounds great! No more serial TN testing needed…we can now make dispositions after only one blood draw and at least slightly decrease ED crowding, right?
The rest of this article is available on Medscape (http://www.medscape.com/viewarticle/752166)
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