They're Here... High Sensitivity Troponin

Short Attention Span Summary

Rapid Rule-out
High sensitivity troponin (hs-cTnI) assays have been widely studied and used clinically in Europe but have only recently been approved in the US.  The authors looked at four strategies: "limit of detection (LOD, hs-cTnI<2ng/L), single cut-off (hs-cTnI<5ng/L), 1h-algorithm (hs-cTnI<5ng/L and 1h-change<2ng/L), and the 0/1h algorithm recommended in the European Society of Cardiology guideline combining LOD and 1h-algorithm."  All four strategies had high diagnostic accuracy, although the single cut-off performed less well in patients presenting within 2 hours of symptom onset.  The 1-hour delta hs-cTnI strategies allowed over half of patients to be ruled out in an hour with 98.4% sensitivity.

Spoon Feed
High sensitivity troponin may allow for a very rapid MI rule out.  If you need a quick refresher on the pros and cons of hs-cTnI (like I did), here are some great resources.

Rick Body, hs-cTnI researcher and editor at St. Emlyn's, wrote his take in this fantastic post.  Also, SGEM did a great podcast called, Oh Baby You're too Sensitive.  St. Emlyn's has an entire section devoted to troponins that's very helpful.  


Abstract

Circulation. 2017 Mar 10. pii: CIRCULATIONAHA.116.025661. doi: 10.1161/CIRCULATIONAHA.116.025661. [Epub ahead of print]

Direct Comparison of Four Very Early Rule-Out Strategies for Acute Myocardial Infarction Using High-Sensitivity Cardiac Troponin I.

Boeddinghaus J1, Nestelberger T1, Twerenbold R2, Wildi K2, Badertscher P2, Cupa J2, Bürge T3, Mächler P3, Corbière S2, Grimm K1, Rubini Giménez M2, Puelacher C2, Shrestha S2, Flores Widmer D2, Fuhrmann J4, Hillinger P1, Sabti Z2, Honegger U2, Schaerli N1, Kozhuharov N2, Rentsch K5, Miró Ò6, López Barbeito B6, Martin-Sanchez FJ7, Rodriguez-Adrada E7, Morawiec B8, Kawecki D8, Ganovská E9, Parenica J9, Lohrmann J4, Kloos W4, Buser A10, Geigy N11, Keller DI12, Osswald S4, Reichlin T2, Müller C13.

Author information:

1 Cardiovascular Research Institute Basel (CRIB); Department of Cardiology, University Hospital Basel, University of Basel, Basel, Switzerland; Department of Internal Medicine, University Hospital Basel, University of Basel, Basel, Switzerland; GREAT network, Rome, Italy.

2 Cardiovascular Research Institute Basel (CRIB); Department of Cardiology, University Hospital Basel, University of Basel, Basel, Switzerland; GREAT network, Rome, Italy.

3 Cardiovascular Research Institute Basel (CRIB); Department of Cardiology, University Hospital Basel, University of Basel, Basel, Switzerland; Emergency Department, University Hospital Zurich, Zurich, Switzerland.

4 Cardiovascular Research Institute Basel (CRIB) & Department of Cardiology, University Hospital Basel, University of Basel, Basel, Switzerland.

5 Laboratory Medicine, University Hospital Basel, Basel, Switzerland.

6 GREAT network, Rome, Italy & Emergency Department, Hospital Clinic, Barcelona, Catalonia, Spain.

7 Servicio de Urgencias, Hospital Clínico San Carlos, Madrid, Spain.

8 2nd Department of Cardiology, Medical University of Silesia, Zabrze, Poland.

9 GREAT network, Rome, Italy & Department of Cardiology, University Hospital Brno, Brno, Czech Republic & Medical Faculty, Masaryk University, Brno, Czech Republic.

10 Blood Transfusion Centre, Swiss Red Cross, Basel, Switzerland & Department of Hematology, University Hospital Basel, Basel, Switzerland.

11 Emergency Department, Kantonsspital Liestal, Liestal, Switzerland.

12 Emergency Department, University Hospital Zurich, Zurich, Switzerland.

13 Cardiovascular Research Institute Basel (CRIB); Department of Cardiology, University Hospital Basel, University of Basel, Basel, Switzerland; GREAT network, Rome, Italy Christian.Mueller@usb.ch.

Abstract

Background -Four strategies for very early rule-out of acute myocardial infarction (AMI) using high-sensitivity cardiac troponin I (hs-cTnI) have been identified. It remains unclear which strategy is most attractive for clinical application.

Methods -We prospectively enrolled unselected patients presenting to the emergency department (ED) with symptoms suggestive of AMI. The final diagnosis was adjudicated by two independent cardiologists. Hs-cTnI levels were measured at presentation and after 1h in a blinded fashion. We directly compared all four hs-cTnI-based rule-out strategies: limit of detection (LOD, hs-cTnI<2ng/L), single cut-off (hs-cTnI<5ng/L), 1h-algorithm (hs-cTnI<5ng/L and 1h-change<2ng/L), and the 0/1h algorithm recommended in the European Society of Cardiology (ESC) guideline combining LOD and 1h-algorithm.

Results -Among 2828 enrolled patients, AMI was the final diagnosis in 451 (16%) patients. The LOD approach ruled-out 453 patients (16%) with a sensitivity of 100% (95% CI, 99.2-100%), the single cut-off 1516 patients (54%) with a sensitivity of 97.1% (95% CI, 95.1-98.3%), the 1h-algorithm 1459 patients (52%) with a sensitivity of 98.4% (95% CI, 96.8-99.2%), and the 0/1h algorithm 1463 patients (52%) with a sensitivity of 98.4% (95% CI, 96.8-99.2%). Predefined subgroup analysis in early presenters (≤2h) revealed significantly lower sensitivity (94.2%, interaction p=0.03) of the single cut-off, but not the other strategies. Two-year survival was 100% with LOD and 98.1% with the other strategies (p<0.01 for LOD vs. each of the other strategies).

Conclusions -All four rule-out strategies balance effectiveness and safety equally well. The single cut-off should not be applied in early presenters, while the three other strategies seem to perform well also in this challenging subgroup. Clinical Trial Registration -https://clinicaltrials.gov/ Identifier: NCT00470587.

PMID: 28283497