Cardiology Corner: High Sensitivity Troponins

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Nurses Edition Commentary

Kathy Garvin, RN and Lisa Chavez, RN
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James C. -

From the PDF show notes "You have a patient with possible ACS. The ECG is non-ischemic. The first high sensitivity troponin is in the positive rangeat 16 ng/L. You can call to admit the patient for rule in." Is that perhaps a mistake, as the following example states "You have a patient with possible ACS. The ECG is non-ischemic. The first high sensitivity troponin taken 4 hours after onset of pain is in the gray zone 40 ng/mL." 16 is positive zone in the first example, 40 is gray zone int he second example.

Anand S., M.D. -

thanks for catching that. reviewing now but I think that 16 should be 52

William S. -

How much troponin elevation from 1st to 2nd draw is considered a positive test?

Anand S., M.D. -

There's an algorithm in the JACC article we referenced that's great and we're building one for the site now.
Basically, if any troponin >/= 52, you're positive
If the delta is > 5-7 ng/L, that typically constitutes a significant rise

Amal M., M.D. -

Agree with Swami.
The algorithm can get a bit complicated and is much easier to follow when you are looking at it, vs. describing in audio. Please take a look at the paper or show notes. It's a well-researched approach to using the hsTNs, and I anticipate that once our hospital gets hsTN we will just use one of the published algorithms also.

Brian D., M.D. -

We have been using the high sensitive troponin assays down under for over 10 years. A few thoughts...

We are at the point that we can measure a circulating level of troponin in just about everybody. It's not like the old days when a measurable troponin was always a concern.

Just about anything that makes the heart "angry" will cause the troponin to go up. You don't need to memorise a list... just know this broad concept.

The reference range for troponin was derived in healthy human volunteers who have been screened out for co-morbid conditions. As such, it is no surprise that when we use it in our typical ED patient population, we see a lot of borderline elevations. This is fine... this is normal... get used to it. Have a plan for dealing with it. Look at their older "baseline" troponin results. Perhaps check a delta value in one or two hours if you are on the fence. Once again, a mildly elevated troponin in a 80 year old with hypertension & mild renal impairment would be considered normal and expected. Don't cause harm by over-diagnosis and treatment. Don't flood your cardiologists and wards with inappropriate admissions.

The cut off of 52 was data snooped and should not be applied to all patients... I would strongly caution blindly adhering to this cut-off. A troponin of 30 in an otherwise healthy younger person with no comorbid illness is a serious red flag.

In summary, the troponin is no longer a "dumb test" where any "positive" result means something. Now more than ever we need to use our brains when interpreting the results.

Amal M., M.D. -

Brian, thanks for your comments.

Ian L., Dr -

The one lesion that is critical to exclude is left main coronary artery stenosis which affects 4-6 % of acute coronary syndromes so if a patient is not getting a catheterization a CCTA with the low dose radiations being performed soon could be very important.

Geoffrey M. -

Hi All, I recall Amal saying a few years ago that HS-Troponin may create more problems than it solves. I have worked in Australian ED’s for the last 14 years and we have had the HS-Tn for quite a while.

In my view it has become a screening test with poor specificity for the emergency doctor who is trying to find the patient with non- stemi changes and a poor history who may be going to have a major occlusion (The patients mentioned by the defence lawyers). That beast is rare in my experience but cardiac catheterisation is not.

I see this test being done by younger doctors not as a confirmatory test of a clinical suspicion of ACS based on history and ECG findings but done as the gold standard for deciding on who is being admitted as a “NSTEMI”. (Regardless of Hx and ECG)

This is concerning on several levels, first I have never had a Troponin level dictate my management of a STEMI. They go to the cath lab based on history and ECG findings.

As reported in EMA June 19(Abstract 24), the ED population (not the general population), those presenting with something more than a sore toe or cold being tested with HS-Tn even when they have no chest pain is around 13%.
The patient with chest discomfort or chest pain is likely to be higher.

However, we let the troponin dictate our management of this less acute patient with less stringent criteria on history and ECG, than a STEMI. This equals admission and cardiac workup and in my experience once worked up it is a rare cardiologist who does not proceed to cath.

The data from the recent ISCHAEMIA trial and the ORBITA before that would make me wonder if we are doing a service to our patients at all with this test. It is certainly sensitive however, it is not specific when low positive and does not tell anyone who is at risk of a major occlusion. Otherwise, why is almost everyone routinely given a cardiac catheter usually after an inconclusive non-invasive investigation?

Amal, you were correct when you said it would not be the answer to our prayers and more is the pity.

Amal M., M.D. -

Thanks for your comments Geoffrey. As you are suggesting, it's really important to consider the pre-test likelihood before sending the test, because of all the false positives. If ACS is not a consideration, don't send the test! (unless you are getting it for a different reason)

Ashley B. -

I can't get the EM RAP 2020 June MP3 Files Zip to work. I specifically want to download the "Cardiology Corner: High Sensitivity Troponins" discussion.

Thanks!

Anand S., M.D. -

Ashley - try now. We reuploaded

Ashley B. -

It works! Thanks so much.

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