Clinical Use of High-sensitivity Cardiac Troponin in Patients With Suspected Myocardial Infarction

Raphael Twerenbold, MD; Jasper Boeddinghaus, MD; Thomas Nestelberger, MD; Karin Wildi, MD; Maria Rubini Gimenez, MD; Patrick Badertscher, MD; Christian Mueller, MD

Disclosures

J Am Coll Cardiol. 2017;70(8):996-1012. 

In This Article

Pros and Cons of the Different Early Algorithms

For all aforementioned diagnostic algorithms, 4 main differences need to be highlighted: First, some algorithms are exclusively cTn-based, whereas others use the combination of cTn with clinical risk scores. Although all algorithms, irrespective of being exclusively cTn-based or including a clinical risk score, need to be integrated and used in conjunction with all information available in the ED, the clinical utility and the need of formal risk scores is a matter of debate. Regarding the diagnosis of MI, the use of hs-cTn seems to obviate the need for routine assessment of formal risk scores because exclusively cTn-based algorithms provide similar NPV and sensitivity for the rule-out of MI as compared with algorithms additionally requiring a low risk score.[22,24,29–31,34–37,47,52,53,55–61] However, clinical scores such as the TIMI or GRACE risk scores may help regarding selection of patients suitable for early discharge from the ED, which is a separate management decision because these scores include variables such as known CAD, older age, and renal dysfunction indicating increased risk of future events.[61]

Second, the early rule-out (and rule-in) algorithms differ in time points chosen for first and serially thereafter performed (hs)-cTn measurements. Single cutoff strategies rule out patients with a single measurement at presentation, the other algorithms use different time intervals between the first and the second measurement of cardiac troponin concentrations (1 h, 2 h, and 3 h) (Figure 2). Third, although the 0/1h, 0/2h, and 0/3h algorithms have the potential to triage patients toward rule-out and rule-in of MI, the other 2 described algorithms can only be used for early rule-out of MI. Fourth, patients presenting very early after chest pain onset require particular attention in order not to miss late rises in hs-cTn. In general, rule-out based on a single measurement approach is not possible in early presenters (≤3 h after chest pain onset) (Figure 3).[27,60] Although pilot data suggest that using very low concentrations of hs-cTnI (2 ng/l or less) may also allow very high NPV in early presenters, further studies seem necessary to confirm the safety of this approach in early presenters.

Figure 2.

Timing of Serial hs-cTn Measurements According to Underlying Algorithm
Orange bar indicates current state-of-the art in the United States. Blue bars indicate timing of second hs-cTn measurement in multiple rapid triage algorithms. Blue bars with fading colors to the right end indicate algorithms allowing direct rule-out and direct rule-in acute myocardial infarction in some patients based on hs-cTn measurements obtained at presentation only, whereas saturated blue bars do not allow direct rule-out/rule-in of myocardial infarction. ADP = accelerated diagnostic pathway; cTn = cardiac troponin; ESC = European Society of Cardiology.

Figure 3.

Diagnostic Performance of Troponin-Based Algorithms and Their Timing of Blood Resampling
Algorithms in blue boxes contain a rule-out strategy only, algorithms in orange boxes contain both a rule-out and a rule-in strategy. Upper panel displays negative predictive values, lower panel displays proportions of patients eligible for rule-out or rule-in (if applicable)(22,24,29–31,34–37,47,52,53,55–61). *Should only be used in patients with chest pain onset of at least 3 h before presentation to the ED. ADP = advanced diagnostic pathway; ED = emergency department; ESC = European Society of Cardiology; MI = myocardial infarction; other abbreviations as in Figure 2.

The clinical value of early rule-out algorithms for safe rule-out of MI is helping guide clinicians identifying patients at very low risk for MI and MACE. However, the decision, which of the available strategies for rapid triage of suspected MI should be used in clinical practice, must be made by each institution individually depending on the locally used cTn assay (sensitive vs. high-sensitivity), wish for additional rule-in guidance, and individual preferences regarding targeted balance between safety and efficacy.

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