From the Guidelines
High sensitivity Troponin (hs-Troponin) is a crucial diagnostic tool in clinical practice, particularly for the rapid diagnosis or exclusion of acute myocardial infarction (AMI) in patients presenting with chest pain or other symptoms suggestive of acute coronary syndrome, as recommended by the 2021 ESC guidelines 1 and further supported by the 2022 AHA/ACC/ASE/CHEST/SAEM/SCCT/SCMR guidelines 2.
Key Points
- The primary utility of hs-Troponin is in the rapid diagnosis or exclusion of AMI, allowing for earlier identification of myocardial injury and implementation of rapid rule-out protocols.
- hs-Troponin can detect troponin levels as low as 1-2 ng/L, which is significantly more sensitive than conventional troponin assays, enabling detection of troponin release within 1-2 hours of symptom onset.
- The test's high sensitivity does come with reduced specificity, as troponin elevation can occur in conditions other than AMI, including heart failure, pulmonary embolism, sepsis, and renal failure, requiring careful clinical interpretation of results in context with the patient's presentation.
- The 2022 AHA/ACC/ASE/CHEST/SAEM/SCCT/SCMR guidelines 2 emphasize the importance of recognizing hs-cTn as the preferred biomarker and endorse the use of 99th percentile upper reference limits to define myocardial injury.
Clinical Implications
- Clinicians should be aware of the analytical aspects related to hs-cTn assays, including the limit of detection and the limit of quantitation, and how they are used clinically, especially for the single sample strategy to rule out acute myocardial infarction.
- The use of hs-Troponin allows for the identification of patients with subclinical myocardial damage who may benefit from more aggressive cardiovascular risk management.
- Conditions such as type 2 myocardial infarction become more common with the use of hs-Troponin, whereas others such as unstable angina become less frequent but still occur, as noted in the 2022 guidelines 2.
Recommendations
- Measurement of hs-Troponin is mandatory in all patients with suspected non-ST-elevation acute coronary syndrome (NSTE-ACS), as recommended by the 2021 ESC guidelines 1.
- Clinicians should use hs-Troponin in conjunction with clinical decision pathways and consider the uniqueness of women and other patient subsets, as emphasized in the 2022 AHA/ACC/ASE/CHEST/SAEM/SCCT/SCMR guidelines 2.
- The derivation of the 99th percentile upper reference limit and the value of sex-specific 99th percentile upper reference limits should be taken into account when interpreting hs-Troponin results, as discussed in the 2022 guidelines 2.
From the Research
Utility of High Sensitivity Troponin in Clinical Practice
The utility of high sensitivity troponin (hs-Tn) in clinical practice is multifaceted, with applications in the diagnosis and management of patients with suspected acute coronary syndrome (ACS) and other cardiac conditions.
- High sensitivity troponin assays can precisely measure blood cardiac troponin concentrations in healthy individuals, enabling the creation of rapid diagnostic algorithms 3.
- Very low troponin concentrations on presentation can accurately rule out acute myocardial infarction (AMI) and enable the discharge of approximately 20% of patients after a single test 3.
- Highly abnormal troponin concentrations on presentation or rapidly rising levels on serial testing can rapidly rule in AMI with high specificity 3.
- The use of high sensitivity troponin assays can result in the diagnosis of myocardial infarction earlier, and may be useful for applications other than acute coronary syndromes, including risk stratifying patients with renal insufficiency, heart failure, cardiac amyloid, and screening elderly patients 4.
Clinical Applications and Decision-Making
High sensitivity troponin measurements can be used in clinical decision-making to identify low-risk patients who can be safely discharged from the emergency department without additional testing.
- An early-discharge strategy using an hs-TnI assay and TIMI score ≤ 1 had similar safety as previously reported, with the potential to decrease the observation periods and admissions for approximately 40% of patients with suspected ACS 5.
- ED physicians must understand the limitations and benefits of hs-cTn levels and how to incorporate the information obtained from these biomarkers into risk scores in order to strengthen disposition decisions and safely discharge patients from the ED 6.
- Newer, high-sensitivity assays for troponin enable the detection of distinctly lower concentrations, and using these assays and very low cut-off concentrations, several rapid diagnostic strategies have been reported to improve diagnosis in acute cardiac care 7.
Risk Stratification and Management
High sensitivity troponin assays can be used to risk stratify patients with suspected ACS, and to identify those who are at low risk of major adverse cardiac events.
- The use of serial cardiac biomarker measurements and structured clinical prediction tools can assist disposition for patients with biomarker-indeterminate results 3.
- Common risk stratification tools, such as the TIMI risk score, can be used in conjunction with hs-Tn measurements to identify cohorts of patients suitable for discharge without additional testing 5, 6.