High Sensitivity Troponin on the SGEM

It’s an SGEM hot off the press! That means that you can comment on this article, and potentially see your comments published next to the original article in the official version of Academic Emergency Medicine. I am also excited to be joining Ken Milne with Corey Heitz as the official co-hosts of the SGEM HOP AEM sessions.

This week, we discuss a new trial on high sensitivity troponin with the lead author and all round excellent chap Dr. Rick Body. Have a listen to the episode and post any questions or comments you have for Dr. Body on the website. It’s a great way to get involved in post-publication peer review. What to you think? Is a single negative high sensitivity troponin as a rule-out strategy ready for prime time?

Body R, Mueller C, Giannitsis E. The Use of Very Low Concentrations of High-sensitivity Troponin T to Rule Out Acute Myocardial Infarction Using a Single Blood Test. Academic emergency medicine. 2016. PMID: 27178492 [Available free, full text here]

This is a secondary analysis of a large, prospective observational cohort (as part of the TRAPID-AMI trial.) They looked at 1282 adult patients presenting to the emergency department with new onset chest pain or symptoms suggestive of acute coronary syndrome that had peaked in the last 6 hours. The were looking at a high sensitivity troponin T on arrival and the primary outcome was acute MI at admission. The major secondary outcome was MACE (major adverse cardiac events). For the primary outcome of acute MI, using the primary strategy of an initial hs-cTnT below the limit of detection (<5ng/L) and no ECG ischemia, the test characteristics are:

  • Sensitivity 99.1% (95%CI 96.7-99.5%)
  • Specificity 43.9% (95%CI 40.9-46.9%)
  • PPV 26.0% (95% CI 23.0–29.2%)
  • NPV 99.6% (95%CI 98.5–100.0%)
  • LR+ 1.76 (95%CI1.67 – 1.86)
  • LR – 0.02 (95% CI 0.01 – 0.09)

In terms of the secondary outcome of MACE, the total 30 day event rate was 1.3%. The actual numbers were 6 MACE events, including only one death, no AMI and 3 revascularizations. I have always had a problem with considering revascularization as a adverse event, as it is so subjective. We know that revascularization is only helpful in the setting of an MI, so if someone goes for revascularization and didn’t have an MI is that really an important outcome, or is it just over-treatment?

My bottom line: Well, I don’t have high sensitivity troponin available, so I don’t have a use for this yet. There is no such thing as 0% risk. I think this information can be used to start a conversation with your patients. Within the context of shared decision making, I already send many patients home after a single negative troponin.

Go check out the episode on the SGEM, put on your skeptical hat, and make sure to comment.

Author: Justin Morgenstern

Community emerg doc, FOAM enthusiast, evidence junkie “One special advantage of the skeptical attitude of mind is that a man is never vexed to find that after all he has been in the wrong.” - William Osler

2 thoughts on “High Sensitivity Troponin on the SGEM”

  1. Would love to see a test/treatment threshold analysis for hs-TnT and coronary angiography, like Jeff Kline did for pulmonary embolism when deriving PERC. As stated, there is no such thing as 0% risk. The “random off-the-street” risk needs to be considered. And we can’t cath everyone presenting for chest pain, can we?

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    1. Thanks for the comment. I have copied it over to http://thesgem.com/2016/09/sgem160-oh-baby-youre-too-sensitive-high-sensitivity-troponin/ so that it is included in the wider conversation.

      Personally – I love the concept of test thresholds and agree we should use them as a tool to discuss the harms and benefits of all the tests that we use. However, distilling the harms and benefits down to a single number is very difficult. For example: how do you weigh the harm of a false positive troponin and carrying a label of disease for the rest of your life against the potential benefit of catching coronary artery disease before a “major adverse cardiac event” occurs? These types types of harms and benefits are qualitatively different, and therefore difficult to distill down into a single quantitative number.

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