The European Society of Cardiology 2015 guidelines recommend including a second sample of hs-cTnI within 3 h of presentation This increases the sensitivity of the hs-TnI assay from 82.3% (at admission) to 98.2% and negative predictive value from 94.7% (at admission) to 99.4%. Combining the 99th percentile at admission with serial changes in troponin increases the positive predictive value to rule in acute coronary syndrome from 75.1% at admission to 95.8% after 3 h.

The 2015 ESC Guidelines recommend the use of a rapid rule out protocol (0 h and 1 h) when hs-cTnI with a validated 0 to1 h algorithm is available.

Training and displaying the clinical algorithm depicting the role of hs-TnI assay in acute cardiac care units and in EDs are an efficient way to deliver the new standard of care to patients. Compared with contemporary troponin assays, the hs-cTn assay accelerates the diagnostic pathway to 0–1 h, thus reducing the time for diagnosis of NSTEMI and hence, its management.

Current evidence suggests that the overall diagnostic accuracy of high-sensitivity cTn tests is not statistically better than that of cTn tests in the diagnosis of AMI in chest pain patients referring to Emergency Department (ED). The overall diagnostic accuracy of hs-cTnT at 99th percentile is statistically lower than that of both cTnT and cTnI. There were insufficient studies and a lack of direct comparisons to reliably estimate the relative diagnostic accuracy of hs-cTnT and hs-cTnI.However, meta-analyses reveal that although hs-cTnI provides less clinical sensitivity than hs-cTnT, it can be overall more specific and more accurate than hs-cTnT. The review also suggests that hs-cTnT can be a better predictor of death and other major cardiovascular adverse events, when compared with cTn tests.

The clinical review found insufficient evidence to determine whether multiple high-sensitivity cTn test measurements can increase the diagnostic accuracy of the tests for AMI or ACS in ED. The questions regarding the effects of high-sensitivity cTn tests on quality of life and readmission rates, as well as the most effective cut-off point and timing of administration, remain unanswered. Well-designed prospective studies, using standard definitions for the diagnosis of AMI and ACS, are still required to determine the most beneficial cTn test and select the best diagnostic thresholds for different cTn tests.

Hello Sergey. Excellent question. 

I have been and continue to be involved in much research in this field including assessment of the ESC 0 & 3h and 0 & 1h guidelines.

Generally, for high-sensitivity troponins we still recommend that at least one measurement be 3 hours after symptom onset.  

Currently, those, including our hospital and all of our country, measure a second troponin 1 to 3 hours later.  We would not recommend "ruling-out" AMI simply on the basis of two troponin measurements less than the 99th percentile. In addition to troponin we use a risk assessment tool (we use EDACS, but also TIMI and possibly HEART are in use) &, of course, we don't risk stratify to low-risk if there is evidence of ischaemic injury on the ECG.  Our work (RCTs) has shown that EDACS & TIMI work well with either contemporary or high-sensitive troponins measured two hours apart.

For patients who are not low-risk, then, final diagnosis normally requires an additional 6-12 hour troponin in the usual manner.

One of the great advantages of high-sensitivity troponin is the information it provides at concentrations much lower than the 99th percentile.  We recently published a meta-analysis which demonstrated the utility of very low levels of a single high-sensitivity troponin T sample measured >3hours after symptom onset to classify patients at low risk and therefore potentially able to be discharged early.

If you are interested in this field I suggest listening to some podcasts by Prof Richard Body and Edd Carlton.  

Here are a couple of links to our latest work:

All the best

John

http://annals.org/aim/article/2619006/rapid-rule-out-acute-myocardial-infarction-single-high-sensitivity-cardiac

http://heart.bmj.com/content/102/16/1270

http://circ.ahajournals.org/content/134/20/1532

http://www.annemergmed.com/article/S0196-0644(16)00002-0/fulltext

Thanks a lot John,

This is exhaustive information and I need time to get acquainted. If I have any questions, I will ask.

Sergey

Thanks a lot John for your response and links to publications. I have received exhaustive information. It is useful for me in a practical sense. I would also like to ask you if you have any information on the use of hs-cTnT in the cardiotoxicity of chemotherapy?

Hello Sergey, that's not something I've looked at myself.  In the back of my mind I recall an abstract somewhere... not much help to you, but I'm sure a quick search of pubmed would find what you are after.