From the Guidelines
High-sensitivity troponin testing at the point of care is recommended for emergency department use to rapidly evaluate patients with suspected acute coronary syndrome, with a preferred approach of serial testing at presentation and 1-3 hours later, as supported by the most recent guidelines 1. The use of high-sensitivity cardiac troponin assays allows for the detection of very small amounts of cardiac troponin in the blood, enabling quicker clinical decision-making compared to traditional laboratory testing.
- The recommended approach involves serial testing at presentation and 1-3 hours later, with specific cutoff values varying by manufacturer.
- For implementation, emergency departments should use FDA-approved devices, ensuring proper staff training on both test administration and result interpretation.
- These tests are particularly valuable in crowded emergency settings as they can safely rule out myocardial infarction in low-risk patients, allowing for earlier discharge decisions and reducing unnecessary admissions. Key considerations for point-of-care testing include the sensitivity and specificity of the assay, as well as the training of staff in test administration and result interpretation, as highlighted in recent guidelines 1.
- High-sensitivity assays are recommended over less sensitive ones, as they provide higher diagnostic accuracy at identical low cost.
- The majority of currently used point-of-care tests cannot be considered sensitive or high-sensitivity assays, and therefore may not provide the same level of diagnostic accuracy. Overall, the use of high-sensitivity troponin testing at the point of care has the potential to improve patient outcomes by enabling rapid and accurate diagnosis of acute coronary syndrome, as supported by recent studies 1.
From the Research
Point of Care (POC) for High Sensitivity Testing in the Emergency Department (ED)
The point of care (POC) for high sensitivity testing in the emergency department (ED) is a crucial aspect of diagnosing myocardial infarction (MI) and other cardiac conditions. The following points highlight the key aspects of POC high sensitivity testing in the ED:
- Diagnostic Accuracy: POC high-sensitivity cardiac troponin I (hs-cTnI) assays have been shown to provide high diagnostic accuracy in patients with suspected MI, with area under the curve (AUC) values comparable to those of central laboratory assays 2, 3.
- Rapid Rule-Out: POC hs-cTnI assays can be used to rapidly rule out MI in patients with suspected cardiac disease, with negative predictive values (NPV) of 100% and sensitivities of 99.68% 4.
- Risk Stratification: POC hs-cTnI assays can be used to stratify patients into low-risk and high-risk categories, with low-risk patients having a NPV of 99.9% and high-risk patients having a positive predictive value (PPV) of 74.5% 5.
- Sample Types: POC hs-cTnI assays can be used with different sample types, including whole blood, fresh/frozen plasma, and capillary finger prick, with high agreement between sample types 2.
- Turnaround Time: POC testing has a short turnaround time, which can support significant efficiencies in the management of patients with suspected MI 5.
- Clinical Performance: POC hs-cTnI assays have been shown to have clinical performance comparable to that of best-validated central laboratory assays, with AUC values of 0.95 and 0.94, respectively 3.
Key Findings
- A single cutoff concentration of <7 ng/L at presentation can rule out 51% of patients with a sensitivity and NPV of 100% 2.
- A 0/1-hour algorithm can rule out 55% of patients with a NPV of 100% and rule in 18% of patients with a PPV of 76.8% 3.
- A 2-hour algorithm using a POC hs-cTnI concentration can enable safe and efficient risk assessment of patients with suspected MI, with a sensitivity of 98.9% and a NPV of 99.9% 5.