Comparison of Point-of-Care and Highly Sensitive Laboratory Troponin Testing in Patients Suspicious of Acute Myocardial Infarction and Its Efficacy in Clinical Outcome.

Background: The use of high-sensitivity troponin (hs-cTnI) assays is recommended in current guidelines for managing patients with acute coronary syndrome (ACS) symptoms. However, point-of-care (POC) assays are frequently used in emergency departments (EDs) to reduce turnaround time and length of stay. This study aimed to compare the results of POC-cTnI testing with those of the gold standard, automated central laboratory testing of troponin (i.e., hs-cTnI). The primary and secondary outcomes were the diagnostic performance of POC-cTnI in diagnosing acute myocardial infarction (AMI) and major adverse cardiovascular events (MACE) during 30 days, respectively.

Materials And Methods: In this diagnostic accuracy study, 136 patients with suspected ACS who were referred or admitted to the Al Zahra Hospital, Shiraz, Iran, were included between March (2020) and July (2020). For the diagnosis of AMI, central laboratory cTnI levels were assessed at the time of presentation (0 hour) and reassessed at least 3 hours later. The POC-cTnI was measured at 0 hour in all patients and at 3 hours if a patient was diagnosed with AMI but had a 0-hour negative result for the POC-cTnI assay. Additionally, the 30-day follow-up period for these participants began on the day of the initial presentation to assess MACE.

Results: Out of 180 patients, 136 patients (median age of 59.5 years; 57.5% male) were left for the qualitative POC-cTnI and hs-cTnI assays. In 86 (63.24%) subjects, hs-cTnI was positive (either initial or serial); however, AMI was diagnosed in 85 patients according to positivity of troponin by hs-cTnI and clinical signs and symptoms, which were diagnosed by a cardiologist. The sensitivity, specificity, and negative predictive value of 0-hour POC-cTnI were observed to be 91.76% (95% CI: 83.77-96.62%), 98.04% (95% CI: 89.55-99.95%), and 87.72% (95% CI: 77.82-93.56%), respectively. Moreover, considering both the 0-hour and 3-hour POC-cTnI, all AMI cases were correctly identified, yielding a perfect test performance result. None of the 50 patients with negative cTnI results (by 0-hour and 3-hour POC-cTnI and hs-cTnI) experienced at least one MACE.

Conclusion: In this small sample-size study, a new qualitative POC-cTnI assay was statistically equal to a hs-cTnI assay in terms of diagnostic accuracy for AMI or MACE in patients with suspected myocardial infarction. The POC-cTnI was observed to be acceptable for the identification of AMI and prediction of MACE in the ED environment.